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An Oscillator Design Based on MOS-NDR Inverter
Cher-Shiung Tsai1 Chung-Chih Hsiao Kwang-Jow Gan Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Shih-Yu Wang Feng-Chang Chiang Chia-Hung Chen Dong-Shong Liang Yaw-Hwang Chen
Department of Electronic Engineering Kun Shan University of Technology Tainan Taiwan 710 ROC
e50401mailksutedutw
Abstract-- First we create a MOS-NDR (negative
differential resistance) cell and then put two MOS-NDR
cells in cascode (totem-pole) structure With MOBILE
(monostable-bistable transition logic element) theorem
we can built a MOS-NDR inverter by placing a NMOS
in parallel with the lower part of the cascode structure
The MOS-NDR inverter cascades two Common-Source
amplifier and feedback to MOS-NDR inverter The
circuit will start an oscillation Such a phenomenon
is similar to ring oscillator The frequency of the
MOS-NDR oscillator will be 116 MHz when voltage is
27 volts Those MOS-NDR devices are adapted from
CIC standard 035um CMOS process
Keywords monostable-bistable transition logic element
(MOBILE) negative differential resistance (NDR)
common-source Amplifier ring oscillator
1 Introduction
There are many kinds of oscillators but we
seldom see an oscillator built by MOS-NDR [1-3]
devices In this thesis we propose a MOS-NDR
Inverter [4-5] by MOBILE [6-8] Theorem Just like
ring oscillator [9] theorem the MOS-NDR inverter
can also implement an oscillator The MOS-NDR
oscillator can reach 100 MHz easily and has low
noise character
The MOS-NDR oscillator can change output
frequency by adjusting MOS sizes or resistance
values Under different voltage the oscillation
frequency will increase as supply voltage increases It
shows the MOS-NDR oscillator is a voltage control
oscillator (VCO) The MOS-NDR oscillator supplies
flexibility and easiness in design
2 MOS-NDR Device
In the beginning we present a MOS- NDR
device which is composed of one PMOS transistor
and three NMOS transistors as shown in Fig 1 This
MOS-NDR device can exhibit various negative
differential resistance (NDR) current-voltage
characteristics by choosing appropriate values for the
transistors parameters
Fig 1 Configuration of MOS-NDR device circuit
In this circuit transistor mn2 acts like a variable
resistor When supply voltage Vdd equals to zero mn2
is off and mn3 is on While supply voltage Vdd
increases transistor mn2 is on and voltage Vc will
decrease to make transistor mn3 turn off Because
transistor mn3 is large size when supply voltage Vdd
increases but total current Idd decreases It creates a
NDR phenomenon Fig 2 shows the I-V
characteristics of the MOS-NDR device by H-spice
simulation
Fig 2 The simulated I-V curve of Fig 1
3 MOS-NDR Inverter
In this work we demonstrate an inverter gate
design that is based on the monostable-bistable
transition logic element (MOBILE) theory A
MOBILE cell is consisted of two NDR devices in
cascade structure as shown in Fig 3 During a period
when the input signal rises the voltage at the output
node between the two NDR devices goes to one of
the two stable states (low and high corresponding to
ldquo0rdquo and ldquo1rdquo in binary logic) depending on which
NDR devices is reached the second positive
differential resistance (PDR) region first The
controlled process obeys a rule the MOS-NDR
device with the smaller peak current is always
reached the second PDR region first Based on the
MOBILE theory and control rule the measured result
of inverter logic is implemented
In Fig 3 when input (Vin) is in high state then
NMOS is on The summation of driver current and
NMOS current is larger than load current the
operating point will be located at point Stable1 and
output state is in low state as Fig 4 shows
Fig 3 Configuration of an inverter by MOS-NDR
circuit
Vin=High Vout=Low Fig 4 When IDriver+VingtILoad operating point at
stable1 and output is in low State
On the contrary in Fig 3 when input (Vin) is in
low state then NMOS is off The driver current is
smaller than load current the operating point will be
located at point Stable2 and output state is in high
state as Fig 5 shows Such an operation just likes an
inverter
Vin=Low Vout=High
stable2 Fig 5 When IDriver ltILoad operating point at stable2
and output is in high state
VS V
I Load Driver
Out(H)
V
I
VS
Driver + VinLoad
Out(L)
stable1
4 MOS-NDR Oscillator
Fig 6 shows the oscillator circuit of MOS-NDR
devices The 1st stage is NDR inverter and 2nd stage
is voltage amplifier which consisted by two common
source amplifiers After MOS-NDR inverter the
output signal could be reduced it needs voltage
amplification The signal of feedback must be the
same as original input signal it needs two
common-source amplifier because common-source
amplifier has high voltage gain and phase change of
180 degrees The theorem of an oscillator is the
feedback signal must be the same as the past original
input signal but out of phase with 180 degrees The
total change of the MOS-NDR oscillator is 540
degrees (= 180 degrees) it satisfies the oscillation
phase The voltage amplifier (2nd stage) also supplies
a time delay to decide the oscillation frequency Such
a phenomenon is similar to ring oscillator All devices
in Fig6 are from CIC standard 035um CMOS
process except resistor R1 and R2 Resistors R1 and
R2 are external devices We put these elements on
bread board to establish the MOS-NDR oscillator and
measure it
Fig 6 Configuration of the MOS-NDR oscillator
circuit
5 Experimental Results In this thesis we use Tektronix TDS3034B
oscilloscope to measure MOS-NDR inverter circuit
and oscillator circuit Fig 7 shows the input (upper)
and output (lower) signals in MOS-NDR inverter
circuit of Fig 3
Fig 7 Input signal (upper) and output signal (lower)
reveal inverter operation
It is an inverter operation the input is 2 Vp-p and
output is 05Vp-p The MOS-NDR inverter is the same
as CMOS inverter except output voltage is not full
swing
Fig 8 shows the MOS-NDR oscillator output
waveform output signal is 14Vp-p and frequency is
1116 MHz as supply voltage is 27 Volts R1 and R2
of the MOS-NDR oscillator (Fig 6) are small
resistance resistors which below 10 Ohms
Fig8 Output waveform of MOS-NDR
oscillator under 27 volts supply voltage
Fig 9 shows MOS-NDR oscillator frequencies
NDR1
NDR2
Vs
(Load)
(Driver)
OUT
mn1
R1 R2
mn2
NMOS
Vin
under different supply voltages The oscillation
frequency increases as supply voltage increases It
shows that the MOS-NDR oscillator is a voltage
control oscillator (VCO) with good linearity The
start oscillation voltage of the MOS-NDR oscillator
is 21 Volts
Fig 9 Oscillator output frequency under different
supply voltage
We also use Tektronix TDS3034B oscilloscope
to measure FFT (fast Fourier transform) response of
Fig 8 In Fig 10 the MOS-NDR oscillator shows
FFT diagram with pretty good low-noise
characteristics
In Fig 10 because the difference between the
highest peak and 2nd highest peak is about 28 dB it
means that the main frequency signal is twenty-five
(102820 =2512) times stronger than the other
frequencies signals If the output signal 15 Vp-p then
the other frequencies signals must be smaller than
006 (=152512) Vp-p
But the differences between the highest peak
and most other peaks is more than 40 dB in Fig 10
so most frequencies signals must be smaller than
0015 Vp-p (1510(4020) = 0015) We can see that
most signals are low-noise except oscillation
frequency signal
Fig 10 Configuration of FFT corresponding to Fig 8
6 Conclusions
In this work we present a MOS-NDR cell which
consisted of three NMOS transistors and one PMOS
transistor We use the cell combined with a large size
NMOS transistor to build an MOS-NDR inverter by
MOBILE (monostable-bistable transition logic
element) theorem then we use the dominant
MOS-NDR inverter and two common-source
amplifiers to establish MOS-NDR oscillator
Such an oscillator shows pretty good response in
frequency domain and low-noise characteristics Itrsquos
also a good voltage control oscillator (VCO) The
MOS-NDR oscillator has both easiness and flexibility
in design items
Acknowledgements
The authors would like to thank the Chip
Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this
work This work was supported by the National
Science Council of Republic of China under the
contract no NSC93-2218-E-168-002
References
1 L O Chua J B Yu and Y Y Yu ldquoNegative resistance
devicesrdquo Int j Cir Appl vol 11 pp 161-186 1983
2 S Sen F Capasso A Y Cho and D Sivco rdquoResonant
tunneling device with multiple negative differential
resistance digital and signal processing applications
with reduced circuit complexityrdquo IEEE Trans
Electron Devices vol 34 pp 2185-2191 1987
3 C S Tsai S B Kuo K J Gan Y H Chen C C Hsu
K R Lee and D S Liang ldquoDesign and Fabrication
of Prototype MOS-NDR Devices by CMOS
Technologyrdquo 2003 EDMS pp 235-238
4 K J Chen T Waho K Maezawa and M Yamamoto
ldquoAn exclusive-OR logic circuit based on controlled
quenching of series-connected negative differential
resistance devicesrdquo IEEE Electron Device Lett vol
17 pp 309-311 1996
5 Cher-Shiung Tsai and Shin-Bin Kuo
ldquoInvestigation of Inverter Design by MOS-NDR
Devives and MOBILE Theoryrdquo 2003 International
Conference on Informatics Cybernetic and Systems
義守大學 pp 296-300
6 K Maezawa H Matsuzaki M Yamamoto
and T Otsuji ldquoHigh-Speed and low-power operation
of a resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-821998
7 K Maezawa T Akeyoshi and T Mizutani
ldquoFunctions and applications of monostable-bistable
transition logic elements (MOBILESrsquos) having
multi-input terminalsrdquo IEEE Trans Electron Devices
vol 41 pp 148-153 1994
8 Tomoyuki Akeyoshi Koichi Maezawa and Takashi
Mizutani ldquoWeighted sum threshold logic operation of
MOBILES (monostable-bistable transition logic
elements) using resonant tunneling transistorsrdquo IEEE
Electron Device Lett vol 14 pp475-477 Dec 1979
9 Adel S Sedra and Kenneth C Smith
ldquoMicroelectronic Circuitsrdquo 5th edition pp 1027
2004
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
increases but total current Idd decreases It creates a
NDR phenomenon Fig 2 shows the I-V
characteristics of the MOS-NDR device by H-spice
simulation
Fig 2 The simulated I-V curve of Fig 1
3 MOS-NDR Inverter
In this work we demonstrate an inverter gate
design that is based on the monostable-bistable
transition logic element (MOBILE) theory A
MOBILE cell is consisted of two NDR devices in
cascade structure as shown in Fig 3 During a period
when the input signal rises the voltage at the output
node between the two NDR devices goes to one of
the two stable states (low and high corresponding to
ldquo0rdquo and ldquo1rdquo in binary logic) depending on which
NDR devices is reached the second positive
differential resistance (PDR) region first The
controlled process obeys a rule the MOS-NDR
device with the smaller peak current is always
reached the second PDR region first Based on the
MOBILE theory and control rule the measured result
of inverter logic is implemented
In Fig 3 when input (Vin) is in high state then
NMOS is on The summation of driver current and
NMOS current is larger than load current the
operating point will be located at point Stable1 and
output state is in low state as Fig 4 shows
Fig 3 Configuration of an inverter by MOS-NDR
circuit
Vin=High Vout=Low Fig 4 When IDriver+VingtILoad operating point at
stable1 and output is in low State
On the contrary in Fig 3 when input (Vin) is in
low state then NMOS is off The driver current is
smaller than load current the operating point will be
located at point Stable2 and output state is in high
state as Fig 5 shows Such an operation just likes an
inverter
Vin=Low Vout=High
stable2 Fig 5 When IDriver ltILoad operating point at stable2
and output is in high state
VS V
I Load Driver
Out(H)
V
I
VS
Driver + VinLoad
Out(L)
stable1
4 MOS-NDR Oscillator
Fig 6 shows the oscillator circuit of MOS-NDR
devices The 1st stage is NDR inverter and 2nd stage
is voltage amplifier which consisted by two common
source amplifiers After MOS-NDR inverter the
output signal could be reduced it needs voltage
amplification The signal of feedback must be the
same as original input signal it needs two
common-source amplifier because common-source
amplifier has high voltage gain and phase change of
180 degrees The theorem of an oscillator is the
feedback signal must be the same as the past original
input signal but out of phase with 180 degrees The
total change of the MOS-NDR oscillator is 540
degrees (= 180 degrees) it satisfies the oscillation
phase The voltage amplifier (2nd stage) also supplies
a time delay to decide the oscillation frequency Such
a phenomenon is similar to ring oscillator All devices
in Fig6 are from CIC standard 035um CMOS
process except resistor R1 and R2 Resistors R1 and
R2 are external devices We put these elements on
bread board to establish the MOS-NDR oscillator and
measure it
Fig 6 Configuration of the MOS-NDR oscillator
circuit
5 Experimental Results In this thesis we use Tektronix TDS3034B
oscilloscope to measure MOS-NDR inverter circuit
and oscillator circuit Fig 7 shows the input (upper)
and output (lower) signals in MOS-NDR inverter
circuit of Fig 3
Fig 7 Input signal (upper) and output signal (lower)
reveal inverter operation
It is an inverter operation the input is 2 Vp-p and
output is 05Vp-p The MOS-NDR inverter is the same
as CMOS inverter except output voltage is not full
swing
Fig 8 shows the MOS-NDR oscillator output
waveform output signal is 14Vp-p and frequency is
1116 MHz as supply voltage is 27 Volts R1 and R2
of the MOS-NDR oscillator (Fig 6) are small
resistance resistors which below 10 Ohms
Fig8 Output waveform of MOS-NDR
oscillator under 27 volts supply voltage
Fig 9 shows MOS-NDR oscillator frequencies
NDR1
NDR2
Vs
(Load)
(Driver)
OUT
mn1
R1 R2
mn2
NMOS
Vin
under different supply voltages The oscillation
frequency increases as supply voltage increases It
shows that the MOS-NDR oscillator is a voltage
control oscillator (VCO) with good linearity The
start oscillation voltage of the MOS-NDR oscillator
is 21 Volts
Fig 9 Oscillator output frequency under different
supply voltage
We also use Tektronix TDS3034B oscilloscope
to measure FFT (fast Fourier transform) response of
Fig 8 In Fig 10 the MOS-NDR oscillator shows
FFT diagram with pretty good low-noise
characteristics
In Fig 10 because the difference between the
highest peak and 2nd highest peak is about 28 dB it
means that the main frequency signal is twenty-five
(102820 =2512) times stronger than the other
frequencies signals If the output signal 15 Vp-p then
the other frequencies signals must be smaller than
006 (=152512) Vp-p
But the differences between the highest peak
and most other peaks is more than 40 dB in Fig 10
so most frequencies signals must be smaller than
0015 Vp-p (1510(4020) = 0015) We can see that
most signals are low-noise except oscillation
frequency signal
Fig 10 Configuration of FFT corresponding to Fig 8
6 Conclusions
In this work we present a MOS-NDR cell which
consisted of three NMOS transistors and one PMOS
transistor We use the cell combined with a large size
NMOS transistor to build an MOS-NDR inverter by
MOBILE (monostable-bistable transition logic
element) theorem then we use the dominant
MOS-NDR inverter and two common-source
amplifiers to establish MOS-NDR oscillator
Such an oscillator shows pretty good response in
frequency domain and low-noise characteristics Itrsquos
also a good voltage control oscillator (VCO) The
MOS-NDR oscillator has both easiness and flexibility
in design items
Acknowledgements
The authors would like to thank the Chip
Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this
work This work was supported by the National
Science Council of Republic of China under the
contract no NSC93-2218-E-168-002
References
1 L O Chua J B Yu and Y Y Yu ldquoNegative resistance
devicesrdquo Int j Cir Appl vol 11 pp 161-186 1983
2 S Sen F Capasso A Y Cho and D Sivco rdquoResonant
tunneling device with multiple negative differential
resistance digital and signal processing applications
with reduced circuit complexityrdquo IEEE Trans
Electron Devices vol 34 pp 2185-2191 1987
3 C S Tsai S B Kuo K J Gan Y H Chen C C Hsu
K R Lee and D S Liang ldquoDesign and Fabrication
of Prototype MOS-NDR Devices by CMOS
Technologyrdquo 2003 EDMS pp 235-238
4 K J Chen T Waho K Maezawa and M Yamamoto
ldquoAn exclusive-OR logic circuit based on controlled
quenching of series-connected negative differential
resistance devicesrdquo IEEE Electron Device Lett vol
17 pp 309-311 1996
5 Cher-Shiung Tsai and Shin-Bin Kuo
ldquoInvestigation of Inverter Design by MOS-NDR
Devives and MOBILE Theoryrdquo 2003 International
Conference on Informatics Cybernetic and Systems
義守大學 pp 296-300
6 K Maezawa H Matsuzaki M Yamamoto
and T Otsuji ldquoHigh-Speed and low-power operation
of a resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-821998
7 K Maezawa T Akeyoshi and T Mizutani
ldquoFunctions and applications of monostable-bistable
transition logic elements (MOBILESrsquos) having
multi-input terminalsrdquo IEEE Trans Electron Devices
vol 41 pp 148-153 1994
8 Tomoyuki Akeyoshi Koichi Maezawa and Takashi
Mizutani ldquoWeighted sum threshold logic operation of
MOBILES (monostable-bistable transition logic
elements) using resonant tunneling transistorsrdquo IEEE
Electron Device Lett vol 14 pp475-477 Dec 1979
9 Adel S Sedra and Kenneth C Smith
ldquoMicroelectronic Circuitsrdquo 5th edition pp 1027
2004
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
4 MOS-NDR Oscillator
Fig 6 shows the oscillator circuit of MOS-NDR
devices The 1st stage is NDR inverter and 2nd stage
is voltage amplifier which consisted by two common
source amplifiers After MOS-NDR inverter the
output signal could be reduced it needs voltage
amplification The signal of feedback must be the
same as original input signal it needs two
common-source amplifier because common-source
amplifier has high voltage gain and phase change of
180 degrees The theorem of an oscillator is the
feedback signal must be the same as the past original
input signal but out of phase with 180 degrees The
total change of the MOS-NDR oscillator is 540
degrees (= 180 degrees) it satisfies the oscillation
phase The voltage amplifier (2nd stage) also supplies
a time delay to decide the oscillation frequency Such
a phenomenon is similar to ring oscillator All devices
in Fig6 are from CIC standard 035um CMOS
process except resistor R1 and R2 Resistors R1 and
R2 are external devices We put these elements on
bread board to establish the MOS-NDR oscillator and
measure it
Fig 6 Configuration of the MOS-NDR oscillator
circuit
5 Experimental Results In this thesis we use Tektronix TDS3034B
oscilloscope to measure MOS-NDR inverter circuit
and oscillator circuit Fig 7 shows the input (upper)
and output (lower) signals in MOS-NDR inverter
circuit of Fig 3
Fig 7 Input signal (upper) and output signal (lower)
reveal inverter operation
It is an inverter operation the input is 2 Vp-p and
output is 05Vp-p The MOS-NDR inverter is the same
as CMOS inverter except output voltage is not full
swing
Fig 8 shows the MOS-NDR oscillator output
waveform output signal is 14Vp-p and frequency is
1116 MHz as supply voltage is 27 Volts R1 and R2
of the MOS-NDR oscillator (Fig 6) are small
resistance resistors which below 10 Ohms
Fig8 Output waveform of MOS-NDR
oscillator under 27 volts supply voltage
Fig 9 shows MOS-NDR oscillator frequencies
NDR1
NDR2
Vs
(Load)
(Driver)
OUT
mn1
R1 R2
mn2
NMOS
Vin
under different supply voltages The oscillation
frequency increases as supply voltage increases It
shows that the MOS-NDR oscillator is a voltage
control oscillator (VCO) with good linearity The
start oscillation voltage of the MOS-NDR oscillator
is 21 Volts
Fig 9 Oscillator output frequency under different
supply voltage
We also use Tektronix TDS3034B oscilloscope
to measure FFT (fast Fourier transform) response of
Fig 8 In Fig 10 the MOS-NDR oscillator shows
FFT diagram with pretty good low-noise
characteristics
In Fig 10 because the difference between the
highest peak and 2nd highest peak is about 28 dB it
means that the main frequency signal is twenty-five
(102820 =2512) times stronger than the other
frequencies signals If the output signal 15 Vp-p then
the other frequencies signals must be smaller than
006 (=152512) Vp-p
But the differences between the highest peak
and most other peaks is more than 40 dB in Fig 10
so most frequencies signals must be smaller than
0015 Vp-p (1510(4020) = 0015) We can see that
most signals are low-noise except oscillation
frequency signal
Fig 10 Configuration of FFT corresponding to Fig 8
6 Conclusions
In this work we present a MOS-NDR cell which
consisted of three NMOS transistors and one PMOS
transistor We use the cell combined with a large size
NMOS transistor to build an MOS-NDR inverter by
MOBILE (monostable-bistable transition logic
element) theorem then we use the dominant
MOS-NDR inverter and two common-source
amplifiers to establish MOS-NDR oscillator
Such an oscillator shows pretty good response in
frequency domain and low-noise characteristics Itrsquos
also a good voltage control oscillator (VCO) The
MOS-NDR oscillator has both easiness and flexibility
in design items
Acknowledgements
The authors would like to thank the Chip
Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this
work This work was supported by the National
Science Council of Republic of China under the
contract no NSC93-2218-E-168-002
References
1 L O Chua J B Yu and Y Y Yu ldquoNegative resistance
devicesrdquo Int j Cir Appl vol 11 pp 161-186 1983
2 S Sen F Capasso A Y Cho and D Sivco rdquoResonant
tunneling device with multiple negative differential
resistance digital and signal processing applications
with reduced circuit complexityrdquo IEEE Trans
Electron Devices vol 34 pp 2185-2191 1987
3 C S Tsai S B Kuo K J Gan Y H Chen C C Hsu
K R Lee and D S Liang ldquoDesign and Fabrication
of Prototype MOS-NDR Devices by CMOS
Technologyrdquo 2003 EDMS pp 235-238
4 K J Chen T Waho K Maezawa and M Yamamoto
ldquoAn exclusive-OR logic circuit based on controlled
quenching of series-connected negative differential
resistance devicesrdquo IEEE Electron Device Lett vol
17 pp 309-311 1996
5 Cher-Shiung Tsai and Shin-Bin Kuo
ldquoInvestigation of Inverter Design by MOS-NDR
Devives and MOBILE Theoryrdquo 2003 International
Conference on Informatics Cybernetic and Systems
義守大學 pp 296-300
6 K Maezawa H Matsuzaki M Yamamoto
and T Otsuji ldquoHigh-Speed and low-power operation
of a resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-821998
7 K Maezawa T Akeyoshi and T Mizutani
ldquoFunctions and applications of monostable-bistable
transition logic elements (MOBILESrsquos) having
multi-input terminalsrdquo IEEE Trans Electron Devices
vol 41 pp 148-153 1994
8 Tomoyuki Akeyoshi Koichi Maezawa and Takashi
Mizutani ldquoWeighted sum threshold logic operation of
MOBILES (monostable-bistable transition logic
elements) using resonant tunneling transistorsrdquo IEEE
Electron Device Lett vol 14 pp475-477 Dec 1979
9 Adel S Sedra and Kenneth C Smith
ldquoMicroelectronic Circuitsrdquo 5th edition pp 1027
2004
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
under different supply voltages The oscillation
frequency increases as supply voltage increases It
shows that the MOS-NDR oscillator is a voltage
control oscillator (VCO) with good linearity The
start oscillation voltage of the MOS-NDR oscillator
is 21 Volts
Fig 9 Oscillator output frequency under different
supply voltage
We also use Tektronix TDS3034B oscilloscope
to measure FFT (fast Fourier transform) response of
Fig 8 In Fig 10 the MOS-NDR oscillator shows
FFT diagram with pretty good low-noise
characteristics
In Fig 10 because the difference between the
highest peak and 2nd highest peak is about 28 dB it
means that the main frequency signal is twenty-five
(102820 =2512) times stronger than the other
frequencies signals If the output signal 15 Vp-p then
the other frequencies signals must be smaller than
006 (=152512) Vp-p
But the differences between the highest peak
and most other peaks is more than 40 dB in Fig 10
so most frequencies signals must be smaller than
0015 Vp-p (1510(4020) = 0015) We can see that
most signals are low-noise except oscillation
frequency signal
Fig 10 Configuration of FFT corresponding to Fig 8
6 Conclusions
In this work we present a MOS-NDR cell which
consisted of three NMOS transistors and one PMOS
transistor We use the cell combined with a large size
NMOS transistor to build an MOS-NDR inverter by
MOBILE (monostable-bistable transition logic
element) theorem then we use the dominant
MOS-NDR inverter and two common-source
amplifiers to establish MOS-NDR oscillator
Such an oscillator shows pretty good response in
frequency domain and low-noise characteristics Itrsquos
also a good voltage control oscillator (VCO) The
MOS-NDR oscillator has both easiness and flexibility
in design items
Acknowledgements
The authors would like to thank the Chip
Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this
work This work was supported by the National
Science Council of Republic of China under the
contract no NSC93-2218-E-168-002
References
1 L O Chua J B Yu and Y Y Yu ldquoNegative resistance
devicesrdquo Int j Cir Appl vol 11 pp 161-186 1983
2 S Sen F Capasso A Y Cho and D Sivco rdquoResonant
tunneling device with multiple negative differential
resistance digital and signal processing applications
with reduced circuit complexityrdquo IEEE Trans
Electron Devices vol 34 pp 2185-2191 1987
3 C S Tsai S B Kuo K J Gan Y H Chen C C Hsu
K R Lee and D S Liang ldquoDesign and Fabrication
of Prototype MOS-NDR Devices by CMOS
Technologyrdquo 2003 EDMS pp 235-238
4 K J Chen T Waho K Maezawa and M Yamamoto
ldquoAn exclusive-OR logic circuit based on controlled
quenching of series-connected negative differential
resistance devicesrdquo IEEE Electron Device Lett vol
17 pp 309-311 1996
5 Cher-Shiung Tsai and Shin-Bin Kuo
ldquoInvestigation of Inverter Design by MOS-NDR
Devives and MOBILE Theoryrdquo 2003 International
Conference on Informatics Cybernetic and Systems
義守大學 pp 296-300
6 K Maezawa H Matsuzaki M Yamamoto
and T Otsuji ldquoHigh-Speed and low-power operation
of a resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-821998
7 K Maezawa T Akeyoshi and T Mizutani
ldquoFunctions and applications of monostable-bistable
transition logic elements (MOBILESrsquos) having
multi-input terminalsrdquo IEEE Trans Electron Devices
vol 41 pp 148-153 1994
8 Tomoyuki Akeyoshi Koichi Maezawa and Takashi
Mizutani ldquoWeighted sum threshold logic operation of
MOBILES (monostable-bistable transition logic
elements) using resonant tunneling transistorsrdquo IEEE
Electron Device Lett vol 14 pp475-477 Dec 1979
9 Adel S Sedra and Kenneth C Smith
ldquoMicroelectronic Circuitsrdquo 5th edition pp 1027
2004
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
References
1 L O Chua J B Yu and Y Y Yu ldquoNegative resistance
devicesrdquo Int j Cir Appl vol 11 pp 161-186 1983
2 S Sen F Capasso A Y Cho and D Sivco rdquoResonant
tunneling device with multiple negative differential
resistance digital and signal processing applications
with reduced circuit complexityrdquo IEEE Trans
Electron Devices vol 34 pp 2185-2191 1987
3 C S Tsai S B Kuo K J Gan Y H Chen C C Hsu
K R Lee and D S Liang ldquoDesign and Fabrication
of Prototype MOS-NDR Devices by CMOS
Technologyrdquo 2003 EDMS pp 235-238
4 K J Chen T Waho K Maezawa and M Yamamoto
ldquoAn exclusive-OR logic circuit based on controlled
quenching of series-connected negative differential
resistance devicesrdquo IEEE Electron Device Lett vol
17 pp 309-311 1996
5 Cher-Shiung Tsai and Shin-Bin Kuo
ldquoInvestigation of Inverter Design by MOS-NDR
Devives and MOBILE Theoryrdquo 2003 International
Conference on Informatics Cybernetic and Systems
義守大學 pp 296-300
6 K Maezawa H Matsuzaki M Yamamoto
and T Otsuji ldquoHigh-Speed and low-power operation
of a resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-821998
7 K Maezawa T Akeyoshi and T Mizutani
ldquoFunctions and applications of monostable-bistable
transition logic elements (MOBILESrsquos) having
multi-input terminalsrdquo IEEE Trans Electron Devices
vol 41 pp 148-153 1994
8 Tomoyuki Akeyoshi Koichi Maezawa and Takashi
Mizutani ldquoWeighted sum threshold logic operation of
MOBILES (monostable-bistable transition logic
elements) using resonant tunneling transistorsrdquo IEEE
Electron Device Lett vol 14 pp475-477 Dec 1979
9 Adel S Sedra and Kenneth C Smith
ldquoMicroelectronic Circuitsrdquo 5th edition pp 1027
2004
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Implementation of R-BJT-NDR Devices and Inverter Circuit by BiCMOS Technology
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shun-Huo Kuo and Hsin-Da Tesng
Department of Electronic Engineering Kun Shan University of Technology Tainan Hsien Taiwan ROC
E-mail Addresssulnmailksutedutw
ABSTRACT
The negative differential resistance (NDR) device studied in this work is composed of the resistors (R) and bipolar junction transistors (BJT) devices This NDR device can be represented as R-BJT-NDR device Comparing to the conventional NDR devices such as resonant tunneling diodes (RTDrsquos) the RTDrsquos are often implemented by the technique of III-V compound semiconductor The fabrication cost of these RTDrsquos is more expensive than that of Si-based technique However our R-BJT-NDR devices and circuits are composed of the resistors and BJT devices Therefore we can fabricate the R-BJT-NDR devices by the standard CMOS or BiCMOS process Furthermore the modulation of the current-voltage (I-V) characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors Finally we demonstrate an inverter circuit design based on the R-BJT-NDR devices and circuits that are implemented by the standard 035μm BiCMOS process
Keywords negative differential resistance (NDR) device resonant tunneling diodes (RTD) inverter circuit 035μm BiCMOS process
1 INTRODUCTION Functional devices and circuits based on
negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristics [1]-[3] The best famous known NDR device is the resonant tunneling diodes (RTD) [4-5] The fabrications of these NDR devices are often based on the technique of compound semiconductor Comparing to silicon-based integrated circuit the cost of compound semiconductor is more expensive However we proposed a NDR device that is composed of the resistors (R) and bipolar junction transistors (BTJ) devices We call this device as R-BJT-NDR device Because this device is totally composed of the R and BTJ devices it is suitable for the process of Si-based CMOS or BiCMOS process
In this paper we investigate the current-voltage (I-V) characteristics by modulating the parameters of the R-BJT-NDR device The fabrication of the device is utilized by 035μm BiCMOS process Furthermore we will demonstrate an inverter design based on the R-BJT-NDR device under 3V bias
2 CIRCUIT ANALYSIS
Figure 1 shows this R-BJT-NDR device
composed of two n-p-n transistors and five resistors During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
kΩ and R5=6kΩ The I-V characteristics can be divided into four regions The first segment (I) of the I-V characteristics represents a situation when Q1 and Q2 are cut off the second segment (II) indicates the case when Q1 is cut off but Q2 is conducted the third segment (III) refers to the state when both Q1 and Q2 are conducted and the forth segment (IV) corresponds to the state when Q1 is saturated but Q2 is cut off
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 The NDR device is composed of two transistors and five resistances
Fig 2 The simulated I-V characteristics by Hspice program
The I-V characteristics of this R-BJT-
NDR device can be modulated by the relative values of the resistors Figures 3 and 4 are the simulated I-V characteristics by varying the values of the resistors R1 and R2 respectively By keeping the other parameters at some fixed values the peak currents and voltages will be increased by increasing the values of the resistor R1 However the peak currents and voltages will be decreased by increasing the
values of the resistor R2 Based on the circuit analysis the peak voltage is approximated to the value of (1+R1R2)xVr1 The parameter Vr1 is the cut-in voltage of the transistor Q1 Therefore this R-BJT- NDR device possesses the ability of the adjustable I-V characteristics during suitably designing the resistance
Fig 3 The simulated I-V characteristics by modulating the values of R1 resistor
Fig 4 The simulated I-V characteristics by modulating the values of R2 resistor
3 MESURED RESULTS
The fabrication of this R-BJT-NDR device is designed based on the standard 035μm SiGe process Figure 5 shows the layout of the R-BJT-NDR device Figure 6 shows the measured I-V characteristics using the Tektronix 370B Programmable curve tracer The parameters are designed as R1=55kΩ R2=33kΩ R3=100kΩ R4=12kΩ and R5=55kΩ The peak current and voltage are about 11mA and 18V respectively The valley
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
current and voltage are about 06mA and 25V respectively Figures 7 and 8 show the measured I-V characteristics by varying the values of R1 and R2 respectively
Fig 5 The layout of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
Fig 6 The measured I-V characteristics of the R-BJT-NDR device
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16
Cur
rent
(mA
)
55K 75K65K
Fig 7 The measured I-V characteristics of the R-BJT-NDR device by varying the R1 values
0 1 2 3 4 5
Voltage (V)
0
04
08
12
16C
urre
nt (m
A)
53K 33K43K
Fig 8 The measured I-V characteristics of the R-BJT-NDR device by varying the R2 values
Based on the measured results this R-BJT-NDR device could exhibit the NDR characteristics by suitably controlling the parameters The tendency of the measured I-V characteristics is satisfactory by comparing to the simulated results
4 INVERTER DESIGN
Figure 9 shows the inverter circuit with a NDR device in series with a NMOS device The input voltage is the gate voltage of the NMOS device
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 9 The inverter circuit design based on this R-BJT-NDR device and a NMOS
The operating principle of the static inverter can be explained by the load-line method as shown in Fig 10 When two devices are connected in series the upper R-BJT-NDR device is treated as a load device to the pull-down NMOS device The operation point (Q) at any bias (VS) can be obtained by the stable intersection point of the two I-V characteristics The voltage value of the operation point Q is the output voltage of the circuit In Fig 9 the load-line curve is the I-V characteristics of the R-BJT-NDR device The driver curve is the I-V characteristics of the NMOS When the input voltage is at low level (0V) the gate voltage of the NMOS is lower than the VT so the NMOS will be located at OFF state The operating point will be located at the intersection point (Q) of two I-V characteristics of the load and driver devices The output voltage will be approximately the same value as the voltage VS The output state is at the high level
Fig 10 The load-line analysis of the inverter circuit
However when the input voltage is at high level (3V) the NMOS will turn on The operating point will be located at the intersection point (Q) of two I-V characteristics As seen the output state is at the low level The key point on designing this inverter circuit is the I-V characteristics of the NMOS device at the high state should be higher than the peak current of the R-BJT-NDR device
The result of the operation of the inverter circuit is shown in Fig 11 The supply voltage VS is chosen at 3V As seen when the input voltage has reached the low state (0V) the output voltage is at the high state (3V) When the input voltage has reached the high state (3V) the output voltage is at the low state (02V) Therefore this circuit can be operated as an inverter
Fig 11 The results of the inverter circuit
5 CONCLUSIONS
We have demonstrated the design and fabrication of the R-BJT-NDR device and inverter circuit based on the standard 035μm BiCMOS process The modulation of the I-V characteristics of this R-BJT-NDR device is easier than that of the RTD device We can obtain different NDR I-V characteristics by simply adjusting the proper values of resistors
This R-BJT-NDR device is more convenient to integrate with other active MOS and BJT devices and passive R L and C devices These phenomena might provide the practical application in some NDR-based
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
circuits It means that the R-BJT-NDR device might have the potential to achieve the design of system-on-a-chip (SOC)
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2215-E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[3] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
[4] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80ndash82 Mar 1998
[5] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
High-Frequency Voltage-Controlled Oscillator Design by MOS-MDR Devices and Circuits
Kwang-Jow Gan Dong-Shong Liang Shih-Yu Wang Chung-Chih Hsiao
Cher-Shiung Tsai Yaw-Hwang Chen and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
This paper describes the design of a novel voltage-controlled oscillator (VCO) based on the new-type MOS-NDR devices and circuits The MOS-NDR device is composed of three N-type metal-oxide-semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) characteristics in its current-voltage (I-V) curve by suitably arranging the parameters The length of three MOS devices is fixed at 035μm The width is designed as 1μm 10μm and 40μm respectively The I-V curve of the MOS-NDR device can exhibit a Λ-type characteristic When we connect a NMOS device with a MOS-NDR device in parallel the total current is the sum of the currents through the NMOS and MOS-NDR devices Therefore we can modulate the total current by the gate voltage of the NMOS Firstly we design a low-power inverter by combining two series-connecting MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) theory Secondly we design an oscillator by cascading this MOS-NDR inverter with the other two common-source amplifiers as shown in Fig 1 The signal will be feedback from the output of the second common-source amplifier to the input of the MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Vds1 or Vds2 This new VCO has a wide range of operation frequency from 065MHz to 155GHz It consumes 7mW in its central frequency of 12GHz using a 24V power supply The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 128 x 45 μm2
Fig 1 The circuit configuration of a novel voltage-controlled oscillator (VCO)
MOS-NDR1
MOS-NDR2 CS
INV
OUT
Vds1 Vds2
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Logic Circuit Design Based on MOS-NDR Devices and Circuits Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang
Cher-Shiung Tsai Yaw-Hwang Chen Shun-Huo Kuo and Chi-Pin Chen
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--We propose a new MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect- transistor (MOS) devices This device could exhibit the negative differential resistance (NDR) characteristics in the current-voltage characteristics by suitably modulating the MOS parameters We design a logic circuit which can operate the inverter NOR and NAND gates The devices and circuits are fabricated by the standard 035μm CMOS process
1 INTRODUCTION
Functional devices and circuits based on negative differential resistance (NDR) devices have generated substantial research interest owing to their unique NDR characteristic [1]-[2] Taking advantage of the NDR feature circuit complexity can be greatly reduced and novel circuit applications have also obtained
Some applications make use of the monostable- bistable transition logic element (MOBILE) as a highly functional logic gate [3]-[4] A MOBILE consists of two NDR devices connected in series and is driven by a suitable bias voltage The voltage at the output node between the two NDR devices could hold on one of the two possible stable states (low and high corresponding to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of peak current (IP) between two devices
We propose a MOS-NDR device that is composed of the metal-oxide-semiconductor field-effect-transistor (MOS) devices Then we design a logic circuit that can operate the inverter NOR and NAND function in the same circuit It is different from the CMOS logic family constructed by NMOS and PMOS devices Finally we fabricate the MOS-NDR devices and logic circuits by standard 035μm CMOS process
2 DEVICE STRUCTURE AND OPERATION
Figure 1 shows a MOS-NDR device which is composed of three NMOS devices and one PMOS device This circuit is derived from a Λ-type topology described in [5]-[6] This MOS-NDR device can exhibit various NDR current-voltage (I-V) characteristics by choosing appropriate MOS parameters Figure 2 shows the simulation results by HSPICE program
If the Vgg voltage is fixed at some value the operation of this MOS-NDR device can be divided into four situations by gradually increasing the bias Vdd The first situation mn1 is saturation mn2 is cutoff mn3 is linear and mp4 is cutoff The second situation mn1 is saturation mn2 is saturation mn3 is from linear to saturation and mp4
is cutoff The third situation mn1 is saturation mn2 is saturation mn3 is saturation and mp4 is cutoff Finally the fourth situation mn1 is saturation mn2 is linear mn3 is cutoff and mp4 is linear until saturation Fig 1 The circuit configuration for a MOS-NDR device
Fig2 Simulation result for the MOS-NDR device by HSPICE program
The value of Vgg voltage will affect the I-V curve especially in its peak current Figure 3 shows the I-V characteristics measured by Tektronix 370B with the Vgg voltage varied from 15V to 33V gradually The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are all fixed at 035μm The I-V characteristic could be divided into three segments as the first PDR segment the NDR segment and the second PDR segment in sequence
mn1
mn2
mn3 mp4
Vgg
Vdd
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 3 The measured I-V characteristics for a MOS-NDR devices with different Vgg voltages
3 LOGIC CIRCUIT DESIGN
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two NDR devices connected in series and is driven by a bias voltage VS The logic circuit configuration is shown in Fig 4 T1 is used as the controlled gate T2 and T3 are the input gates with square wave signal The width parameters are all 5μm The upper NDR1 device is treated as a load device to the pull-down NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit
Fig 4 Configuration of the logic circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1 NMOS The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate voltage (T1) so is ITotal
Figure 5 shows the measure I-V characteristics of a MOS-NDR device with T1 varying from 0 to 33V gradually As seen we can modulate the peak current of the MOS-NDR device through T1 gate
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 5 Measured I-V characteristics with different T1 voltages
If the IP of the driver is smaller than IP of the load (with T2 or T3 OFF) the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 6 The operation point Q is located at the second PDR region of the driverrsquos I-V curve On the other hand a bigger peak current (with T2 or T3 ON) of the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the second PDR region of the loadrsquos I-V curve Therefore an inverter operation can be obtained at the output node between the two NDR devices Similarly if we design the logic function according to the MOBILE theory and truth table we can obtain the NOR and NAND gate logic operation Fig 6 The MOBILE operation is dependent on the relative difference in the peak current of load and driver devices
4 EXPERIMENT RESULTS
The MOS-NDR devices and logic circuits are fabricated by the standard 035μm CMOS process The length parameters for all MOS are fixed at 035μm The width parameters of the two MOS-NDR devices are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The width parameters for T1 T2 and T3 are fixed at 5μm
For the inverter operation T2 gate is chosen as the input square wave with signal varied from 0 to 2V The supply voltage VS is fixed at 15V that is bigger than 2VP
T1
T2 T3
VS
Vout
NDR1 Load
NDR2 Driver
Driver + T2 or T3
Out(L) VS V
Load
Driver
Out(H)
Q Q
I
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
but is small than 2VV voltage The operation of T1 control gate is cutoff The Vgg voltages are 33V and 28V for NDR1 and NDR2 respectively The inverter operation is shown in Fig 7 As seen when the input voltage has reached the low state (0V) the output voltage will be at the high state On the other hand when the input voltage has reached the high state (2V) the output voltage must be at the low state
Fig 7 The measured results for the logic circuit
For the NOR gate operation T2 and T3 gates both are the input square wave with signal varied from 0 to 2V The period of T2 is two times of the period of T3 signal The controlling gate T1 is fixed at 12V According to the truth table when the input T2 and T3 gates are located at low level the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device Then the stable operating point will be located at the relative ldquohighrdquo level at the output node If one (or both) of the input T2 and T3 is (are) located at high voltage level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 devices The stable operating point will be located at the relative ldquolowrdquo level at this case Therefore we design the Vgg voltages with 33V and 25V for NDR1 and NDR2 respectively
As for the operation of a NAND gate when the input T2 and T3 gates both are located at high level the peak current of ITotal of NDR2 device must be bigger than the peak current of ITotal of NDR1 device The stable operating point will be located at the relative ldquolowrdquo level On the other hand the peak current of ITotal of NDR2 device must be smaller than the peak current of ITotal of NDR1 device for the other cases The stable operating point will be located at the relative ldquohighrdquo level Therefore the control gate T1 is designed fixed at 33V The Vgg voltages are fixed at 33V and 25V for NDR1 and NDR2 respectively
The parameters are designed and shown in Table I The operation results for this logic circuit are shown in Fig 7 respectively As seen we can obtain the inverter NOR and NAND gate operation at the same circuit only by modulating the relative parameters
Table I The parameters condition for the logic circuit
Inverter NOR NAND
VS 15V 15V 15V
T1 OFF 12V 33V
T2 INPUT INPUT INPUT
T3 OFF INPUT INPUT
NDR1 Vgg 33V 33V 33V
NDR2 Vgg 28V 25V 25V
5 CONCLUSIONS
We have demonstrated the logic circuit design based on the MOS-NDR devices and circuits This circuit design is operated according to the principle of MOBILE theory Our MOS-NDR devices and circuits are fabricated by the technique of Si-based CMOS technique The fabrication cost will be cheaper than that of resonant tunneling diodes (RTD) implemented by the technique of compound semiconductor Furthermore our NDR devices are composed of the MOS devices so these NDR devices are easy to combine with other devices and circuit to achieve the system-on-a-chip (SoC) If the integrated circuit is fabricated with transistor dimensions less than 01μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore the MOS-NDR devices and circuit have high potential in the SoC applications
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[1] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[2] T H Kuo H C Lin R C Potter and D ShupeldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[3] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[4] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[5] C Y Wu and K N Lai ldquoIntegrated Λ -type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
[6] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential- resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Novel Voltage-Controlled Oscillator Design by MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Chung-Chih Hsiao Cher-Shiung Tsai Yaw-Hwang Chen
Shih-Yu Wang Shun-Huo Kuo Feng-Chang Chiang and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a
voltage-controlled oscillator (VCO) based on the negative differential resistance (NDR) devices The NDR devices used in the work is fully composed by the metal-oxide- semiconductor field-effect-transistor (MOS) devices This MOS-NDR device can exhibit the NDR characteristic in its current-voltage curve by suitably arranging MOS parameters The VCO is constructed by three low-power MOS-NDR inverter This novel VCO has a range of operation frequency from 151MHz to 268MHz It consumes 245mW in its central frequency of 260MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupied an area of 120 x 86 μm2
I Introduction
In recent years several new applications based on resonant tunneling diode (RTD) have been reported [1]-[4] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the compound semiconductor and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new MOS-NDR device that is fully composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve We call this NDR device as MOS-NDR device Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
We will demonstrate a novel voltage-controlled oscillator (VCO) designed based on the MOS-NDR devices and circuit The VCO is constructed by three cascading low-power MOS-NDR inverters The basic inverter is composed by two series-connected MOS-NDR devices according to the monostable-bistable transition logic element (MOBILE) The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We design and implement this VCO by the 035μm CMOS process
II MOS-NDR Device and Inverter DESIGN
Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors This circuit can show the Λ-type NDR I-V characteristic by suitably arranging the MOS parameters Figure 2 shows the I-V curve measured by Tektronix-370B curve trace with the width parameters of the three MOS devices as 1μm 10μm and 40μm respectively The MOS length is fixed at 035μm The VGG is fixed at 33V
Fig 1 The circuit configuration of a Λ-type MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristic for a MOS-NDR device
If we connect a NMOS with a MOS-NDR device in
parallel we can modulate the peak current of MOS-NDR devicersquos I-V curve through the gate voltage of NMOS The circuit is shown in Fig 3 The total current ITotal is the sum of the currents through the MOS-NDR and NMOS devices ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
voltage (VG) so is ITotal Our inverter circuit design is based on two series-connected MOS-NDR devices as shown in Fig 4 This circuit is called as monostable-bistable transition logic element (MOBILE) [5]-[6] The input node is located at the VG gate The output node is located between the two MOS-NDR devices When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit
However when the bias voltage is larger than two peak voltages but smaller than two valley voltages (2VV) there will be two possible stable points (bistable) The intersection point located at the NDR region for two I-V curve will be regarded as unstable point The two stable points that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively are shown in Fig 5 A small difference between the peak currents of the two devices determines the state of the circuit If the peak current of the driver device is smaller than that of the load device the operation point will be located at the high state On the other hand if the peak current of the driver device is bigger than that of the load device through the VG voltage the operation point will be located at the low state
Fig 3 The peak current of MOS-NDR device can be controlled by the VG voltage
Fig 4 The MOS-NDR inverter designed by MOBILE theory
Fig 5 The bistable states when VS is bigger than2VP but smaller than 2VV
By suitably determining the parameters of devices and circuits we can obtain the inverter result as shown in Fig 6 Figure 7 illustrates the relationship between the input bias VS and the power dissipation for a MOS-NDR inverter The power dissipation of this inverter is 575mW using a 2V power supply
Fig 6 The MOS-NDR inverter result
16 2 24Input Bias (V)
0
2
4
6
8
10
Pow
er D
issi
patio
n (m
W)
Fig 7 The power dissipation for a MOS-NDR inverter
III VCO DESIGN
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
The circuit configuration of the novel VCO is shown in Fig 8 The oscillator circuit is composed of three cascading MOS-NDR inverters The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter This VCO is designed and fabricated by the standard 035μm CMOS process and occupied an area of 120 x 86 μm2 Figure 9 shows the layout of VCO
Fig 8 The circuit configuration of the VCO
Fig 9 The layout of VCO
IV SIMULATION RESULTS
Under suitable parameters design we can obtain an oscillator with its frequency proportional to the magnitude of input bias VS Figure 10 shows the simulated waveform of the oscillator under 2V bias voltage by HSPICE program Figure 11 shows its spectrum
Figure 12 illustrates the relationship between the input bias and the oscillation frequency This VCO has a range of operation frequency from 151MHz to 268MHz The relationship between the power dissipation and input bias is shown in Fig 13 It consumes 245mW in its central frequency of 260MHz using a 2V power supply
Fig 10 The simulated waveform of the oscillator
Fig 11 The simulated waveform of the oscillator
16 2 24Input Bias (V)
120
160
200
240
280
Freq
uenc
y (M
Hz)
Fig 12 The relationship between the input bias and the oscillation frequency
16 2 24Input Bias (V)
0
10
20
30
40
Pow
er D
issi
patio
n (m
W)
Fig 13 The power dissipation for a VCO
V Conclusions We have designed a voltage-controlled oscillator
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
(VCO) based on the Λ-type MOS-NDR devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters For chip area die consideration we use fully MOS devices instead of LC-tank structure The oscillation frequency is from 151MHz to 268MHz This VCO is designed by the standard 035μm CMOS process If we fabricated this VCO by 018μm CMOS process the oscillation frequency will be increased above GHz
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
REFERENCES
[7] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE
Trans Electron Devices vol 34 pp 2185-2191 1987 [8] T H Kuo H C Lin R C Potter and D ShupeldquoA
novel AD converter using resonant tunneling diodesIEEE J Solid-State Circuits vol 26 pp 145-149 1991
[9] LO Chua ldquoSimplicial RTD-Based Cellular Nonlinear Networksldquo IEEE Trans on Cir and Sys-I Fundamental Theo and Appl vol50 no4 April 2003
[10] Y Kawano Y Ohno S Kishimoto K Maezawa T Mizutani and K Sano ldquo88 GHz dynamic 21 frequency divider using resonant tunnelling chaos circuitrdquo Electron Lett vol 39 no 21 pp 1546-48 2003
[11] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[12] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Design and Fabrication of Voltage-Controlled Oscillator by Novel MOS-NDR Device
Kwang-Jow Gan Chung-Chih Hsiao Shih-Yu Wang Feng-Chang Chiang Cher-Shiung Tsai Yaw-Hwang Chen Dong-Shong Liang Chun-Da Tu Wei-Lun Sun Chia-Hung Chen
Chun-Ming Wen Chun-Chieh Liao Jia-Ming Wu and Ming-Yi Hsieh
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper describes the design of a
voltage-controlled oscillator (VCO) using the novel MOS-NDR devices The VCO circuit is constructed by cascading a MOS-NDR inverter with the other two common-source amplifiers This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
Index Terms mdash voltage-controlled oscillator MOS- NDR inverter 035μm CMOS process
I INTRODUCTION
Negative differential resistance (NDR) devices have attracted considerable attention in recent years because of their potential as functional devices for circuit applications [1]-[3] Taking full advantages of NDR we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption However these NDR devices such as resonant tunneling diodes (RTD) are fabricated by the III-V compound semiconductor Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
In this paper we proposed a MOS-NDR device that is made of metal-oxide-semiconductor field- effect-transistor (MOS) devices During suitably controlling the MOS parameters we can obtain the NDR characteristic in its I-V curve Because this NDR device is consisted of the MOS devices it is much more convenient to combine other devices and circuits to achieve the SoC by standard Si-based CMOS or BiCMOS process
The voltage-controlled oscillator (VCO) is one of the important components in the phase-locked loop We will demonstrate a VCO circuit based on the MOS-NDR devices and circuits This oscillator is composed of an NDR-based inverter two common source amplifiers and a CMOS inverter This novel
VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V The fabrication of this VCO is based on the standard 035μm CMOS process and occupied an area of 003mm2
II MOS-NDR INVERTER
Our logic circuit design is based on the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
parallel The total current ITotal is the sum of the currents through the NMOS and MOS-NDR2 That is ITotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO Design
The CMOS LC-tank oscillators have shown an excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area The oscillator circuit is composed of a NDR inverter two common source amplifier and a CMOS inverter as shown in Fig 6
Fig 6 The circuit configuration of a novel VCO
The VCO signal will be feedback from the output of the second common source amplifier to the input of the MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 003 mm2
Fig 7 Layout and PAD of the VCO chip
Figure 8 shows the output waveform with 156MHz oscillation frequency under 23V bias voltage Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias Figure 9 shows the relationship between the input bias and the oscillation frequency This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Fig 8 The 156MHz oscillation frequency under 23V bias voltage
16 2 24 28Voltage (V)
0
50
100
150
200
250
Freq
uenc
y (M
Hz)
Fig 9 Oscillation frequencies of the VCO
IV CONCLUSIONS
We have designed a voltage-controlled-oscillator (VCO) based on the Λ-type NDR-based devices and circuits The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 119MHz to 188MHz under the bias voltage from 18V to 28V
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2815-C-168-005-E
REFERENCES
[1] F Capasso S Sen A C Gossard A L Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
[2] H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
[3] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[4] K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
[5] K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
[6] C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Investigation of MOS-NDR Voltage Controlled Ring
Oscillator Fabricated by CMOS Process
Kwang-Jow Gan Dong-Shong Liang Chung-Chih Hsiao Cher-Shiung Tsai and Yaw-Hwang Chen
Abstract- A voltage-controlled ring oscillator
(VCO) based on novel MOS-NDR circuit is described This MOS-NDR circuit is made of metal-oxide- semiconductor field-effect-transistor (MOS) devices that can exhibit the negative differential resistance (NDR) current-voltage characteristic by suitably arranging the MOS parameters The VCO is constructed by three low-power MOS-NDR inverters This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply This VCO is fabricated by 035μm CMOS process and occupy an area of 0015 mm2
I Introduction In recent years several new applications based on
resonant tunneling diode (RTD) have been reported [1]-[3] The negative-differential-resistance (NDR) current-voltage (I-V) characteristics of the RTD devices have several advantages and they may have high potential as functional devices due to their unique folding I-V characteristics However these RTD devices are fabricated by the III-V compound material and process Therefore this kind of NDR device is difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
Therefore we proposed a new NDR device that is totally composed of metal-oxide-semiconductor field-effect-transistor (MOS) devices We can obtain the NDR characteristic in its I-V curve by suitably arranging the MOS parameters We call the NDR device to be as MOS-NDR device in this work Because this NDR device is consisted of the MOS devices yet it is much more convenient to combine other devices and circuits to achieve the SoC by standard CMOS process
Our novel voltage-controlled ring oscillator (VCO) is constructed by three low-power MOS-NDR inverters The MOS-NDR inverter logic gate can be obtained by connecting two MOS-NDR devices in series according to the Monostable-Bistable transition Logic Element (MOBILE) theory [4]-[5] The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter Under suitable design we can obtain an oscillator with its frequency proportional to the magnitude of input bias We demonstrate this VCO based on the standard 035μm CMOS process
II MOS-NDR DEVICE AND INVERTER
Our logic circuit design is based on the MOBILE theory A MOBILE circuit consists of two MOS-NDR devices connected in series and is driven by a bias voltage VS as shown in Fig 1 The MOS-NDR device used in this work that is made of three NMOS and an external bias VGG It can present a λ-type I-V curve with suitable control the width of each MOS device [6] The value of Vgg voltage will affect the peak current of the I-V curve of the MOS-NDR device
Fig 1 Inverter circuit configuration for a MOBILE MOS-NDR device
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 2 The measured results for the MOS-NDR device by modulating the VGG voltage
Figure 2 shows the I-V curve with the VGG voltage varying from 15V to 33V by a step of 03V The width parameters of the three MOS devices are designed as 1μm 10μm and 40μm respectively The MOS lengths
Kwang-Jow Gan Dong-Shong Liang Chung-Chih HsiaoCher-Shiung Tsai and Yaw-Hwang Chen are with the Department of Electronic Engineering the Kun Shan University Taiwan
E-mail sulnmailksutedutw
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
are all fixed at 035μm The MOS-NDR2 device is connected with a NMOS in parallel The total current Itotal is the sum of the currents through the NMOS and MOS-NDR2 That is Itotal= IMOS+IMOS-NDR2 Since IMOS is modulated by the Vin voltage so is ITotal Therefore we can modulate the peak current of this combined circuit through the magnitude of the Vin as shown in Fig 3 The Vin voltages are varied from 1V to 22V with a step 03V
Fig 3 Modulation of peak current by Vin voltage
The upper MOS-NDR1 device is treated as a load device to the pull-down MOS-NDR2 driver device When the bias voltage is smaller than twice the peak voltage (2VP) there is one stable point (monostable) in the series circuit However when the bias voltage is bigger than 2VP but is smaller than 2VV there is two possible stable points (bistable) that respect the low and high states (corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small difference between the peak currents of the series-connected NDR devices determines the state of the circuit The selection of the stable operating point could be explained by means of the load-line method as shown in Fig 4
If the peak current of the driver is smaller than the peak current of the load the circuit switches to the stable point Q corresponding to a high output voltage as shown in Fig 4 As shown the operation point Q is located at the positive differential resistance (PDR) region of the loadrsquos I-V curve In order to obtain a small peak current in MOS-NDR2 device we can adjust the value of the Vgg voltage to be smaller than that of MOS-NDR1 device On the other hand a bigger peak current in the driver will result in the stable point Q with low output voltage At this time the operation point Q is located at the PDR region of the driverrsquos I-V curve Thus the state of the circuit is determined by the magnitude of the peak current of the MOS-NDR2 driver device that can be controlled by the Vin voltage Therefore an inverter operation can be obtained at the output node between the two MOS-NDR devices By suitably determining the parameters of devices and circuits we can obtain one of the inverter logic results as shown in Fig 5
Fig 4 MOBILE operation of an inverter circuit
Fig 5 Measured result for an inverter circuit
III VCO DESIGN The CMOS LC-tank oscillators have shown an
excellent phase noise performance with low power consumption However the large chip area of the inductor L has become critical drawback in LC VCOs On the other hand the ring VCOs have the advantages such as the ease of integration with CMOS technique and the smaller chip area The oscillation frequency of the ring oscillator is inversely proportional to the number of delay stages N Employing fewer delay stages can also reduce the power dissipation and chip area
The circuit configuration of the novel VCO is shown in Fig 6 The oscillator circuit is composed of three low-power MOS-NDR inverters Every MOS-NDR inverter is regarded as a delay stage With the 2V supply voltage the current consumption is about 12mA The signal will be feedback from the output of the third MOS-NDR inverter to the input of the first MOS-NDR inverter The output of every circuit is affected by the previous one and then the last circuit output goes back to affect the first MOS-NDR inverter There has been transmission delay between every circuit so that it makes circuit produce oscillation The novel VCO is fabricated using 035μm CMOS technology as shown in Fig 7 The layout of this VCO is occupied an area of 0015 mm2
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 6 Circuit configuration of the ring VCO
Fig 7 Layout and PAD of the VCO chip
16 18 2 22 24Voltage (V)
0
40
80
120
160
200
Freq
uenc
y (M
Hz)
Fig 8 The relationship between the oscillation frequency
and the bias VS
Figure 8 shows the measured results for the ring VCO circuit If we changed the value of VS voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the VS
voltage from 16V from 24V step 02V the oscillator frequency is increased from 38GHz to 162MHz
IV CONCLUSIONS We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and circuits The VCO is composed of three cascading low-power MOS-NDR inverters The NDR devices are all made of the MOS devices Therefore we can fabricate the VCO circuit based on the standard 035μm CMOS process In comparison with the LC-tank VCO structure this novel MOS-NDR VCO will occupy less chip area This novel VCO has a range of operation frequency from 38MHz to 162MHz It consumes 24mW in its central frequency of 118MHz using a 2V power supply
Furthermore even if the integrated circuit is fabricated with transistor dimensions less than 035μm technique the applications based on the MOS-NDR devices and circuits are still useful We can predict the oscillation frequency will be capable for GHz operation by the Hspice simulated results from the 018μm CMOS process Therefore it can provide some useful applications in the NDR-based circuit and system design
ACKNOWLEDGMENTS The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
REFERENCES F Capasso S Sen A C Gossard A L
Hutchinson and J H English ldquoQuantum-well resonant tunneling bipolar transistor operating at room temperaturerdquo IEEE Electron Device Lett vol EDL-7 pp 573-576 1986
H Matsuzaki T Itoh and M Yamamoto ldquoA Novel High-Speed Flip-Flop Circuit Using RTDs and HEMTsrdquo Proc IEEE 9th Great Lakes Sympo on VLSI Michigan 1999 pp154-157
H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
K Maezawa and T Mizutani ldquoA new resonant tunneling logic gate employing monostable-bistable transitionrdquo Japan J ApplPhys vol 32 pt 2 no 1AB p L42 Jan 15 1993
K J Chen K Maezawa and M Yamamoto ldquoInP-based high-performance monostable-bistable transition logic elements (MOBILEs) using integrated multiple-input resonant-tunneling devicesrdquo IEEE Electron Device Lett vol 17 pp 127-129 1996
C Y Wu and K N Lai ldquoIntegrated λ-type differential negative resistance MOSFET devicerdquo IEEE J Solid-State Circuits vol 14 pp 1094-1101 1979
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
A NAND Gate Design Based on MOS-NDR Devices and Circuits Implemented by CMOS Technology
Kwang-Jow Gan Chi-Pin Chen Long-Xian Su To-Kai Liang Cher-Shiung Tsai Yaw-Hwang Chen Chung-Chih
Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
A NAND logic circuit design based on the
MOS-NDR devices is demonstrated The MOS-NDR
device is consisted of the metal-oxide-semiconductor
field-effect-transistor (MOS) devices This device could
exhibit the negative differential resistance (NDR)
characteristics in the current-voltage curve by suitably
arranging the parameters of the MOS devices As a result
we design a NAND logic operation based on MOS-NDR
devices and circuits which is implemented by the
standard CMOS process
Keywords NAND logic circuit negative differential
resistance (NDR) characteristics 35μm CMOS process
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristic [1]-[2] Taking advantage of the NDR
feature circuit complexity can be greatly reduced and
novel circuit applications have also obtained
Some applications make use of the monostable-
bistable transition logic element (MOBILE) as a highly
functional logic gate [3]-[4] A MOBILE consists of two
NDR devices connected in series and is driven by a
suitable bias voltage The voltage at the output node
between the two NDR devices could hold on one of the
two possible stable states (low and high corresponding
to ldquo0rdquo and ldquo1rdquo) depending on the relative difference of
peak current between two devices
In this paper we propose a MOS-NDR device that is
composed of the metal-oxide-semiconductor field-
effect-transistor (MOS) devices Then we design a logic
circuit that can operate the NAND function We fabricate
the circuit by standard CMOS process
II The MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS devices and one PMOS device
This circuit is derived from a Λ-type topology described
in [5]-[6] This MOS-NDR device can exhibit various
NDR current-voltage (I-V) characteristics by choosing
appropriate parameters for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The value of Vgg voltage will affect the I-V curve
especially in its peak current Figure 2 shows the I-V
characteristics measured by Tektronix 370B with the
Vgg voltage varied from 15V to 33V gradually The
width parameters of the gate of the MOS devices are
described as mn1=5μm mn2=100μm mn3=10μm and
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
mp4=100μm The length parameters of four MOS are all
fixed at 035μm The I-V characteristics could be divided
into three segments as the first PDR segment the NDR
segment and the second PDR segment in sequence
0 04 08 12 16
Voltage (V)
00
10
20
30
Cur
rent
(mA
)
Vgg=33V
Vgg=2V
Vgg=15V
Vgg=25V
Vgg=3V
1st PDR NDR
2ndPDR
Fig 2 The measured I-V characteristics for a MOS-NDR devices with
different Vgg voltages
III Logic Circuit Design
Our logic circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 3 shows the logic circuit configuration T1 is the
control gate T2 and T3 are the input square wave signal
The width parameters are all 5μm The upper NDR1
device is treated as a load device to the pull-down NDR2
driver device When the bias voltage is smaller than
twice the peak voltage (2VP) there is one stable point
(monostable) in the series circuit However when the bias
voltage is larger than two peak voltages but smaller than
two valley voltages (2VV) there is two possible stable
points (bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit
The circuit shown at upper left corner of Fig 4 is a
MOS-NDR device with parallel connection of a T1
NMOS The total current ITotal is the sum of the currents
through the MOS-NDR and NMOS devices
ITotal=INDR+IMOS Since IMOS is modulated by the gate
voltage (T1) so is ITotal Figure 4 shows the measure I-V
characteristics of a MOS-NDR device with T1 varying
from 0 to 33V gradually As seen we can modulate the
peak current of the MOS-NDR device through T1 gate
Fig 3 The logic circuit configuration
0 04 08 12 16
Voltage (V)
00
20
40
60
Cur
rent
(mA
)
T1 varied from 0Vto 33V
0V1V15V2V
25V3V
33V
Fig 4 The measured I-V characteristics with different T1
voltages
If the IP of the driver is smaller than IP of the load
(with T2 or T3 OFF) the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve On the other hand
a bigger peak current (with T2 or T3 ON) of the driver
will result in the stable point Q with low output voltage
At this time the operation point Q is located at the
second PDR region of the loadrsquos I-V curve Therefore an
inverter operation can be obtained at the output node
between the two NDR devices Similarly if we design
the logic function according to the MOBILE theory and
truth table we can obtain the NAND gate logic
operation
Fig 5 The MOBILE operation is dependent on the
relative difference of peak current
IV Experiment Results
The MOS-NDR devices and logic circuits are
fabricated based on the standard 035μm CMOS process
The length parameters for all MOS are fixed at 035μm
The supply voltage VS is fixed at 15V
For the NAND gate operation T2 and T3 gates both
are the input square wave The period of T2 is two times
of the period of T3 signal The control T1 gates is 33V
The Vgg voltages are 33V and 25V for NDR1 and
NDR2 respectively We design the logic circuit based on
the truth table and MOBILE theory The selection of the
operation point is dependent on the relative difference of
peak current between two devices Figure 6 shows the
measured result for the NAND logic circuit
Fig 6 The measured results for the logic circuit
V Conclusions We have demonstrated the NAND logic circuit
design based on the MOS-NDR devices and circuits
This circuit design is operated according to the principle
of MOBILE theory Our NDR devices and circuits can
be fabricated by the technique of Si-based CMOS
technique The fabrication cost will be cheaper than that
of resonant tunneling diodes (RTD) implemented by the
technique of compound semiconductor
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this chip This
work was supported by the National Science Council of
Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K Maezawa H Matsuzaki M Yamamoto and T
Otsuji ldquoHigh-speed and low-power operation of a
resonant tunneling logic gate MOBILErdquo IEEE
Electron Device Lett vol 19 pp 80-82 1998
4 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
5 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
6 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Oscillator Design by MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Shih-Yu Wang Chung-Chih Hsiao Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The oscillator design based on the negative
differential resistance (NDR) devices and circuits is
demonstrated The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices An inverter logic gate can be obtained by
connecting two MOS-NDR devices in series according to
the monostable-bistable transition logic element
(MOBILE) theory As a result we will demonstrate an
oscillator circuit with frequency 100MHz
Keywords MOS-NDR device MOBILE oscillator
circuit
I Introduction Functional devices and circuits based on negative
differential resistance (NDR) devices have generated
substantial research interest owing to their unique NDR
characteristics [1]-[3] The best famous known NDR
devices are Esaki diodes and resonant tunneling diodes
(RTD) The fabrications of these NDR devices are based
on the technique of compound semiconductor
Comparing to Silicon-based integrated circuit the cost of
compound semiconductor is more expensive However
we proposed a new NDR device that is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices We call this device to be as MOS-NDR device
Because this device is totally composed of MOS devices it is suitable for the process of Si-based CMOS process
First we demonstrate an inverter circuit based on
the MOS-NDR device Then we design an oscillator
circuit composed of a NDR inverter a common source
amplifier and a CMOS inverter The measured results
show the oscillator frequency is about 100MHz
II The MOS-NDR Devices Figure 1 shows a prototype MOS-NDR device
which is composed of three NMOS transistors and one
PMOS transistor This circuit is derived from a Λ-type
topology described in [4] The gate of mn3 is connected
to the output of the inverter formed by mn1 and mn2 It
can exhibit various NDR current-voltage characteristics
by choosing appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
The operation of this MOS-NDR device can be
divided into four situations by gradually increasing the
bias Vdd The first situation represents a condition when
mn1 is saturated mn2 is cutoff mn3 is linear and mp4 is
cutoff The second situation indicates the case when mn1
is saturated mn2 is saturation mn3 is from linear to
saturated and mp4 is cutoff The third situation refers to
the state when mn1 is saturated mn2 is saturated mn3 is
saturated and mp4 is cutoff Finally the fourth situation
corresponds to the state when mn1 is saturated mn2 is
mn1
mn2
mn3
Vdd
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
NDR2(Driver)
NDR1(Load)
VS
Out
VG
linear mn3 is cutoff and mp4 is saturated Therefore we
can obtain various NDR I-V characteristics by choosing
appropriate values for MOS parameters
Figure 2 shows the measured I-V characteristics by
modulating the width of mn1 The other width
parameters of the gate of the MOS devices are described
as mn2=100μm mn3=10μm and mp4=100μm The
length parameters of four MOS are all fixed at 035μm
The Vgg voltage is fixed at 33V
0 04 08 12 16 2Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
)
5μm
1μm
10μm
modulation of mn1
Fig 2 The measured I-V characteristics for a MOS-NDR
devices by modulating the width of mn1
Fig 3 The peak current of MOS-NDR device could be
controlled by the VG voltage
Figure 3 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal
III Inverter Circuit Design
Our inverter circuit design is based on the MOBILE
theory A MOBILE circuit consists of two NDR devices
connected in series and is driven by a bias voltage VS
Figure 4 shows the configuration of a MOBILE circuit
The VG gate is used as the input signal gate The upper
NDR1 device is treated as a load device to the pull-down
NDR2 driver device When the bias voltage is smaller
than twice the peak voltage (2VP) there is one stable
point (monostable) in the series circuit However when
the bias voltage is bigger than 2VP but is smaller than
2VV there is two possible stable points (bistable) that
respect the low and high states (corresponding to ldquo0rdquo and
ldquo1rdquo) respectively A small difference between the peak
currents of the series-connected NDR devices determines
the state of the circuit
Fig 4 The circuit configuration of an inverter
If the peak current of the driver is smaller than the
peak current of the load the circuit switches to the stable
point Q corresponding to a high output voltage as shown
in Fig 5 The operation point Q is located at the second
PDR region of the driverrsquos I-V curve In order to obtain a
small peak current in NDR2 device we can adjust the
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
value of the Vgg voltage to be smaller than that of NDR1
device On the other hand a bigger peak current in the
driver will result in the stable point Q with low output
voltage At this time the operation point Q is located at
the second PDR region of the loadrsquos I-V curve Thus the
state of the circuit is determined by the magnitude of the
peak current of the NDR2 driver device that can be
controlled by the input VG gate Therefore an inverter
operation can be obtained at the output node between the
two NDR devices Figure 6 shows the simulated result
for an inverter logic circuit The VS is fixed at 15V
Fig 5 The MOBILE operation of an inverter circuit
Fig 6 The simulated results of an inverter logic based on
the MOBILE theory
IV Oscillator Design
The oscillator circuit is composed of a NDR inverter
a common source amplifier and a CMOS inverter as
shown in Figure 7
Fig 7 The circuit configuration of an oscillator based on
the MOS-NDR devices
When the output of NDR inverter rises from VOL to
VOH it makes impact to the next CMOS inverter The
output of voltage will rise from VOH to VOL The output
of INV1 will connect to the common source amplifier
The common source amplifier can provide the
180∘phase reverse The voltage output will rise form
VOL to VOH As shown in Fig 7 every circuit output is
affected by the previous one and then the last circuit
output goes back to affect the first circuit-NDR inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
We add a CMOS inverter (INV2) in back of the
output of the common source amplifier We design and
modulate the kNkP ratio to a smaller value which makes
the output of the common source amplifier obtain a
perfect wave The INV2 can be used as a load as well
Figure 8 shows the measured results of an oscillator
The INV1 and INV2 with number SN74HC04 and
MM74HC04 respectively are used in the measurement
The oscillator frequency is about 100MHz
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 8 The measured results of an oscillator
V Conclusions We have designed and demonstrated an oscillator
circuit based on the MOS-NDR devices and MOBILE
theory The circuit configuration is similar to the ring
oscillator We first obtain an inverter output from the
MOS-NDR MOBILE circuit Then we connect the
output of the MOS-NDR inverter with a common source
amplifier and a CMOS inverter The result shows that the
oscillator frequency is about 100MHz
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 1 S Sen F Capasso A Y Cho and D Sivco
ldquoResonant tunneling device with multiple negative
differential resistance digital and signal processing
applications with reduced circuit complexity
IEEE Trans Electron Devices vol 34 pp
2185-2191 1987
2 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
3 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
4 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp 1094-1101
1979
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Frequency Multiplier Using Multiple-Peak MOS-NDR Devices and Circuits
To-Kai Liang Kwang-Jow Gan Cher-Shiung Tsai Yaw-Hwang Chen Chi-Pin Chen
Long-Xian Su Chung-Chih Hsiao Feng-Chang Chiang and Shih-Yu Wang
Department of Electronic Engineering Kun Shan University of Technology
Abstract
The design of a frequency multiplier based on the
multiple-peak negative differential resistance (NDR)
devices and circuits is demonstrated The NDR device
used in this work is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices The multiple-peak NDR circuit is obtained by
connecting two MOS-NDR devices in series This circuit
can exhibit three stable operating points These
phenomena can be used in a circuit that multiplied the
input signal frequency by a factor of three We design
and fabricate the MOS-NDR device and frequency
multiplier circuit by the standard 035μm CMOS process
Keywords multiple-peak NDR circuit MOBILE
oscillator circuit
I Introduction The negative differential resistance (NDR) devices
have attracted considerable attention in recent years for
their potential as functional devices for circuit
application There are many applications in signal
processing for a device that exhibits more than one NDR
region To obtain the multiple-peak current-voltage (I-V)
NDR characteristics we can connect two or more NDR
devices in series or parallel
The best famous known NDR device is the resonant
tunneling diode (RTD) [1]-[2] The fabrications of the
RTD devices are based on the technique of compound
semiconductor Comparing to Silicon-based integrated
circuit the fabrication cost of compound semiconductor
is more expensive However we proposed a new NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the process
of Si-based CMOS process
In this paper we demonstrate a two-peak NDR
device by combining two discrete MOS-NDR devices in
series and obtain two NDR regions with characteristics
suitable for applications such as frequency multipliers
II The Multiple-Peak MOS-NDR Devices Figure 1 shows a MOS-NDR device which is
composed of three NMOS transistors and one PMOS
transistor The gate of mn3 is connected to the output of
the inverter formed by mn1 and mn2 This circuit is
derived from a Λ-type topology described in [3] It can
exhibit various NDR I-V characteristics by choosing
appropriate values for transistors
Fig 1 The circuit configuration for a MOS-NDR device
mn1
mn2
mn3
Vdd
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
I
V
IP
RP1
RN1
VV
RT
1
VP
IV
VT
IT
Fig 2 The piecewise-linear PWL approximation of the
I-V characteristics of a MOS-NDR device
We use the piecewise-linear (PWL) approximation
method to describe the I-V characteristics of a
MOS-NDR device According to the PWL
approximation method we could model the I-V curve of
a one-peak NDR device by three segments as shown in
Fig 2 The electrical parameters are defined as follows
RP is the positive differential resistance RN is the
negative differential resistance and RT is the resistance
of the right-most region VP is peak voltage and VV is
the valley voltage IP is the peak current and IV is the
valley current VT and IT are the corresponding voltage
and current at one point on RT segment We have
supposed that TPN RRR conggt
When two identical NDR devices are connected in
series there are two peaks and valleys in the combined
I-V characteristics Their combined I-V characteristics
can be obtained by the load-line technique as shown in
Fig 3 The upper NDR device is treated as a load device
to the pull-down NDR device (driver device) Therefore
the load line is the I-V characteristics of the upper NDR
device and represented by the dashed lines in Fig 3 The
I-V characteristics of the driver device are shown by the
solid lines As seen in Fig 3(a) the load line will move
towards the right along the voltage axis as the bias
voltage is increased gradually from zero voltage to high
voltage We can obtain the series current for different
bias voltage by the stable intersection point of the two
I-V characteristics
Therefore the forward I-V characteristics follow the
breakpoints A B C D and E in order as shown in Figs
3(a)-3(f) The combined two-peak I-V characteristics are
shown in Fig 4
Fig 3 The load-line analysis for two MOS-NDR devices
in series
Fig 4 The combined I-V characteristics for two
series-connected MOS-NDR devices
We fabricate the MOS-NDR devices by the standard
035μm CMOS process Figure 5 shows the layout of a
MOS-NDR device The width parameters of the gate of
the MOS devices are described as mn1=10μm
mn2=100μm mn3=10μm and mp4=100μm The length
parameters of four MOS are all fixed at 035μmThe bias
Vgg is fixed at 33V for both two devices The
experimental I-V curve measured by HP-4155A for two
series-connected MOS-NDR devices connected in series
is shown in Fig 6
As shown we can obtain two peaks and valleys in
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
the combined I-V characteristics The measured results
are similar to our load-line analysis as shown in Fig 4
Since absolutely identical NDR devices do not exist in
practice the peak and valley currents between two
devices are slightly different Therefore there are small
differences between the measured and analytic results
Fig 5 The layout of a MOS-NDR device
0 1 2 3 4
Voltage (V)
0
05
1
15
2
25
Cur
rent
(mA
) Load Line (Rout)
Q1
Q2
Q3
Fig 6 The measured I-V results for two MOS-NDR
devices connected in series
III Frequency Multiplier Design The two-peak I-V characteristics can form three
stable states in their positive differential resistance
segments Figure 6 shows a 2KΩ load line which
intersects the I-V characteristics to form three stable
points It can be used for signal processing applications
such as frequency multiplying and waveform scrambling
and descrambling An example of frequency
multiplication is illustrated in Fig 7
Fig 7 Circuit configuration of a frequency multiplier
When a sawtooth waveform was applied to the circuit in
Fig 8(a) the output was also a sawtooth with a
frequency three times higher than the input frequency as
shown in Fig 8(b)
-04 0 04 08Time (ms)
0
04
08
12
16
2
Vol
tage
(V)
(a)
-04 0 04 08Time (ms)
0
02
04
06
08
Vol
tage
(V)
(b)
Fig 8 (a) Sawtooth waveform that was applied to the
circuit shown in Fig 7 (b)Output waveform across the
resistor
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
IV Conclusions
In this work we have demonstrated the two-peak
NDR circuit with two MOS-NDR devices in series The
two-peak I-V characteristics can form three stable states
in their positive differential resistance segments As a
result we demonstrated a frequency multiplier using two
MOS-NDR devices and circuits that can multiply the
input signal frequency by a factor of three
The conventional NDR devices such as resonant
tunneling diodes (RTD) are implemented by the
technique of III-V compound semiconductor The
fabrication cost of these RTD devices is more expensive
than that of Si-based technique However our NDR
devices and circuits are composed of MOS devices
Therefore we can fabricate the MOS-NDR device and
frequency multiplier circuit by the standard CMOS
process
Acknowledgement The authors would like to thank the Chip
Implementation Center (CIC) for their great effort and
assistance in arranging the fabrication of this MOS-NDR
chip This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 7 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
8 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
9 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Design and Simulation of Voltage Controlled Oscillator with High Frequency by Negative Differential Resistance Devices and Integrated Circuits
To-Kai Liang Shih-Yu Wang Kwang-Jow Gan Cher-Shiung Tsai Chung-Chih Hsiao
Feng-Chang Chiang Yaw-Hwang Chen Chi-Pin Chen and Long-Xian Su
Department of Electronic Engineering Kun Shan University of Technology
Abstract The voltage controlled oscillator (VCO) design
based on the negative differential resistance (NDR)
devices and integrated circuits is demonstrated The
oscillator frequency is proportional to the magnitude of
input bias The NDR device is composed of
metal-oxide-semiconductor field-effect-transistor (MOS)
devices Therefore the oscillator can be fabricated by
standard CMOS process We discuss the simulated
results under 035μm CMOS process
Keywords voltage controlled oscillator negative
differential resistance CMOS process
I Introduction In recent years several new memory and logic
circuits based on negative differential resistance (NDR)
devices have been reported [1]-[3] The current-voltage
(I-V) characteristics of the NDR devices have several
advantages and they may have high potential as
functional devices due to their unique folding I-V
characteristics These novel devices also might overcome
the limits imposed by the complexity of conventional
transistor
First we design an inverter based on the negative
differential resistance (NDR) device We present a NDR
device that is composed of metal-oxide-semiconductor
field-effect-transistor (MOS) devices We call this device
to be as MOS-NDR device Because this device is totally
composed of MOS devices it is suitable for the CMOS
process
Then we design an oscillator circuit based on the
035μm CMOS technique This oscillator is composed of
an NDR-based inverter two common source amplifiers
and a CMOS inverter We find that the oscillator
frequency is proportional to the magnitude of input bias
Therefore it is suitable for the voltage controlled
oscillator (VCO) design
II The Λ-type NDR Device Figure 1 shows a Λ-type MOS-NDR device which
is composed of three NMOS transistors This circuit can
show the a Λ-type I-V characteristic [4]
Fig 1 TheΛ-type NDR device circuit
Figure 2 shows the I-V curve measured by
Tektronix-370B curve trace with the width parameters
of the gate of the MOS devicesWQ1=1μmWQ2
=10μmWQ3 =40μm Each MOS length is fixed at
035μm The VGG is fixed at 33V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2C
urre
nt(m
A)
W1=1uW2=10uW3=40u VGG=33V
(1) (2) (3) (4)
Fig 2 The measured I-V characteristics of a Λ-type
MOS-NDR device
The I-V characteristics of this NDR device could be
controlled by the VGG voltage Figure 3 shows the I-V
curve with the VGG voltage varying from 15V to 33V
by a step of 03V
0 05 1 15 2 25
Voltage(V)
0
04
08
12
16
2
Cur
rent
(mA
)
W1=1uW2=10uW3=40uVGG=15V~33V Step=03V
VGG=15V
VGG=33V
Fig 3 The measured I-V characteristics of a NDR device
by varying the VGG voltages
III The Inverter based on Λ-type NDR Device
Figure 4 shows the circuit with the parallel
connection of a NMOS and a MOS-NDR device The
total current ITotal is the sum of the currents through the
MOS-NDR and NMOS devices ITotal=INDR+IMOS
Since IMOS is modulated by the gate voltage (VG) so is
ITotal Figure 5 shows the measured I-V characteristics of
the Λ-type MOS-NDR device with VG varying from 0V
to 19V
Fig 4 The peak current of Λ-type MOS-NDR device
could be controlled by the VG voltage
Fig 5 The measured I-V characteristics of the Λ-type
MOS-NDR device with VG varying from 0V to 19V
Our inverter circuit design is based on two
series-connected MOS-NDR devices as shown in Fig 6
This circuit is called as monostable-bistable transition
logic element (MOBILE) [5] The input node is located
at the VG gate The output node is located between the
two MOS-NDR devices When the bias VS is bigger than
two peak voltage (2VP) but is smaller than two valley
voltage (2VV) there is two possible stable points
(bistable) that respect the low and high states
(corresponding to ldquo0rdquo and ldquo1rdquo) respectively A small
difference between the peak currents of the
series-connected NDR devices determines the state of the
circuit By suitably determining the parameters of
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
devices and circuits we can obtain the inverter logic gate
as shown in Fig 7
Fig 6 The inverter circuit design based on the MOBILE
Fig 7 The measured result for an inverter circuit
IV Oscillator Design The oscillator circuit is composed of a NDR inverter
two common source amplifier and a CMOS inverter as
shown in Figure 8
Fig 8 The circuit configuration of an oscillator
When the output of NDR-based inverter rises from
VOL to VOH it makes impact to the common source
amplifier Because it is an invert amplifier it provides a
360∘reverse for two cascade common source amplifiers
When it works to amplify the output of voltage it makes
the next circuit work The output of every circuit is
affected by the previous one and then the last circuit
output goes back to affect the first NDR-based inverter
There has been transmission delay between every circuit
so that it makes circuit produce oscillation
The final stage of the inverter is composed of a
CMOS inverter We design the kNkP ratio to a smaller
value that makes the output of common source amplifiers
to obtain a perfect wave All of the circuit components
are made of NMOS devices so we can design the
oscillator according to the standard 035μm CMOS
process Figure 9 shows the 035μm CMOS layout of the
circuit
Fig 9 The layout of the oscillator
V Simulation Results Figure 10 shows the simulated results for the output of every stage If we changed the value of Vds2 voltage we can find that the oscillation frequency is proportional to the magnitude of input bias If we modulate the Vds2 voltage from 18V
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
from 3V step 02V the oscillator frequency is increased from 065GHz to 155GHz Therefore this circuit can be regarded as the voltage-controlled-oscillator (VCO) It can provide some useful applications in the NDR-based circuit and system design Further theory analysis and experiment results are under progressing It will be discussed elsewhere in the future
Fig 10 The simulated results for the output of every
stage shown in Fig 8
16 2 24 28 32Voltage (V)
06
08
1
12
14
16
Freq
uenc
y (G
Hz)
Fig 11 The relationship between the frequency and the
bias Vds2
VI Conclusions We have designed a voltage-controlled-oscillator
(VCO) based on the Λ-type NDR-based devices and
circuits according to the standard 035μm CMOS process
The oscillator circuit configuration is similar to the ring
oscillator From the simulated analysis we find that the
oscillation frequency is proportional to the magnitude of
bias The oscillator frequency is about 155 GHz under
3V
Acknowledgement This work was supported by the National Science
Council of Republic of China under the contract no
NSC93-2218-E-168-002
References 10 S Sen F Capasso A Y Cho and D Sivco
ldquo Resonant tunneling device with multiple
negative differential resistance digital and signal
processing applications with reduced circuit
complexityIEEE Trans Electron Devices vol
34 pp 2185-2191 1987
11 T H Kuo H C Lin R C Potter and D Shupe
ldquoA novel AD converter using resonant tunneling
diodesIEEE J Solid-State Circuits vol 26 pp
145-149 1991
12 A F Gonzalez and P Mazumder ldquoMultiple-valued
signed-digit adder using negative
differential-resistance devicesrdquo IEEE Trans
Comput vol 47 pp 947-959 1998
13 C Y Wu and K N Lai ldquoIntegrated Λ -type
differential negative resistance MOSFET devicerdquo
IEEE J Solid-State Circuits vol 14 pp
1094-1101 1979
14 K J Chen K Maezawa and M Yamamoto
ldquoInP-based high-performance monostable-bistable
transition logic elements (MOBILEs) using
integrated multiple-input resonant-tunneling
devicesrdquo IEEE Electron Device Lett vol 17 pp
127-129 1996
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Four-Valued Memory Circuit Designed by Multiple-Peak MOS-NDR Devices and Circuits
Dong-Shong Liang Kwang-Jow Gan Long-Xian Su Chi-Pin Chen Chung-Chih Hsiao Cher-Shiung Tsai
Yaw-Hwang Chen Shih-Yu Wang Shun-Huo Kuo and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University of Technology Taiwan ROC
Abstract--This paper describes the design of a four-valued memory cell based on a three-peak MOS-NDR circuit We connect three MOS-NDR devices in parallel that can create a three-peak current-voltage curve by suitably arranging the parameters Due to its folding I-V characteristics multiple -peak NDR device is a very promising device for multiple -valued logic application This memory cell structure can be easily extended to implement more states in a memory circuit
I Introduction
The multiple-peak negative differential resistance (NDR) devices offer much promise for multi-valued memory circuits [1]-[4] Taking full advantages of the NDR device we can reduce circuit complexity to enhance circuit performance in terms of operation speed chip area and power consumption Previously published memory circuits usually consisted of resonant tunneling diode (RTD) in series However these RTD devices are fabricated by the III-V compound semiconductor and process Therefore the RTD devices are difficult to combine with other devices and circuits to achieve the system-on-a-chip (SoC)
However the MOS-NDR device used in this work is fully composed of metal-oxide-semiconductor field-effect- transistor (MOS) devices During suitably arranging the MOS parameters we can obtain the NDR characteristic in its I-V curve Therefore we can implement the MOS-NDR devices and related circuits by Si-based CMOS or BiCMOS process So it is much more convenient to achieve the SoC
Numerous multiple-peak applications using two or more NDR devices in series or vertical integration create the multiple-peak I-V characteristics These devices could be treated as independent devices connected in series However we use three MOS-NDR devices connected in parallel to create the three-peak I-V characteristics The three-peak MOS-NDR device can have four stable states at its positive differential resistance (PDR) segments during suitable load design Using this three-peak MOS-NDR device with a constant current source load a four-state multi-valued memory circuit is demonstrated by the 035μm CMOS process
II the multiple-peak MOS-NDR Device
The prototype MOS-NDR device as shown in Fig 1 is composed of three NMOS transistors and one PMOS transistor The gate of mn3 is connected to the output of the inverter formed by mn1 and mn2 It can exhibit various NDR current-voltage characteristics by choosing appropriate values for transistors Figure 2 shows the simulation results by HSPICE program The width parameters are designed as mn1=5μm mn2=100μm mn3=10μm and mp4=100μm The length parameters are
all fixed at 035μm The VGG is 33V This circuit also can show the Λ-type NDR I-V characteristic as shown in Fig 3 if we take off the mp4 device from Fig 1
Fig 1 Circuit configuration of a MOS-NDR device
Fig 2 Simulated result for the MOS-NDR device by HSPICE program
Numerous multiple-peak applications often use two or
more NDR devices in series or vertical integration to create the multiple-peak I-V characteristics But it is difficult to simulate the series circuit of NDR devices [5] Therefore we design the multiple-peak NDR characteristics by connecting the MOS-NDR devices in parallel as shown in Fig 4 The MOS-NDR1 and MOS-NDR2 are designed by the N-type devices The MOS-NDR3 is designed by the Λ-type device The mn4 mn8 and mn9 devices are used to delay the turn-on voltage of MOS-NDR2 and MOS-NDR3 respectively The simulated result is shown in Fig 5 The Vgg voltages are all fixed at 33V
mn1
mn2
3mp4
VGG
VDD
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 3 Simulated result for the Λ-type I-V characteristic
Fig 4 Circuit configuration of the multiple-peak MOS- NDR device
Fig 5 Simulated result for the multiple-peak MOS-NDR device
III MULTIPLE ndashVALUED MEMORY CIRCUIT DESIGN
Due to the folding I-V characteristics multiple-peak NDR device is a very promising device for multi-valued logic application The obvious method to bias the multiple-peak NDR device into the multiple stable states is to use a resistor or a constant current source as a load as shown in Fig 6 respectively For the three-peak MOS-NDR device there are at most four stable states from V1 to V4 When the series resistor exceeds the magnitude of the NDR of the multiple-peak device the series resistor can be considered as a load resistance which intersects the PDR regions of the multiple-peak device at multiple stable states When one locates the stable points one always locates the points of intersection on the PDR region because all the intersection points on the NDR region are always unstable
Fig 6 The I-V characteristics for multiple-valued memory circuit using either a resistor load or a constant current source
If a constant current source is used as the load device the current could be adjusted through appropriate device parameters to a value approximately halfway between the peak and valley current of the multiple-peak NDR device By comparing to the resistor load configuration the memory circuit using the constant current source as the load device has two advantages the better noise margins for the four stable states and the low power dissipation [6]
Fig 7 The four-valued MOS-NDR memory circuit
Figure 7 shows the four-state MOS-NDR memory circuit The voltage to be stored is provided at the cell input and loaded by momentarily enabling the write clock The input voltage then controls the voltage at the multiple-peak MOS-NDR node When the write clock is disabled the voltage across the MOS-NDR device adjusts to the nearest stable operating point thereby storing the input value at one of the four discrete levels
A saw-tooth wave is applied to the input of the memory circuit with amplitude of 35V A square wave is then applied to the write gate input which alternately turns the MOS on and off The output of this memory circuit gives the four stable memory values as shown in Fig 8 We can understand the attractive feature for this memory circuit for the constant-current-source load is that the noise margin would remain the same with a further increase in the number of current peaks of the multiple-peak MOS-NDR device The design of this memory circuit is demonstrated by the standard 035μm CMOS process We design the constant current source by the MOS devices
currentsource
V1 V2V3
V4
R
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 8 Simulated results for the MOS-NDR memory circuit
V CONCLUSIONS
In this work we have demonstrated the three-peak MOS-NDR circuit with three MOS-NDR devices connected in parallel The series combination of this device with a constant-current-source load is used to demonstrate the operation of a four stable state memory cell Because all of the devices used in this circuit are fully composed of MOS devices we can fabricate this memory circuit by the standard Si-based CMOS or BiCMOS process Furthermore this MOS-NDR device and circuit will be easy to integrate with other device and circuit to achieve the goal of SoC
Acknowledgments
The authors would like to thank the Chip Implementation Center (CIC) of Taiwan for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218- E-168-002
References
[13] S Sen F Capasso A Y Cho and D SivcoldquoResonant tunneling device with multiple negative differential resistance digital and signal processing applications with reduced circuit complexityIEEE Trans Electron Devices vol 34 pp 2185-2191 1987
[14] J P A van der Wagt H Tang T P E Broekaert A C Seabaugh and Y C Kao rdquoMultibit resonant tunneling diode SRAM cell based on slew-rate addressingrdquo IEEE Trans Electron Devices vol 46 pp 55-62 1999
[15] S J Wei and H C Lin ldquoMultivalued SRAM cell using resonant tunneling diodesrdquo IEEE J Solid-St Circuits vol 27 pp 212-216 1992
[16] A C Seabaugh Y C Kao and H T Yuan rdquoNine-state resonant tunneling diode memoryrdquo IEEE Electron Device Lett vol 13 pp 479-481 1992
[17] K J GanldquoHysteresis phenomena for the series circuit of two identical negative differential resistance devicesJapanese Journal of Applied Physics Vol 40 No 4A pp 2159-2164 2001
[18] Z X Yan and M J Deen rdquoA new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion loadrdquo IEEE J Solid-State Circuits vol 27 pp 1198-1202 1992
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
An oscillator design based on MOS differential amplifier by simulation
Cher-Shiung Tsai Ming-Yi Hsieh Jia-Ming Wu Chun-Chieh Liao Jeng-Lung Wu Kwang-Jow
Gan Yaw-Hwang Chen Dong-Shong Liang Chia-Hung Chen and Chung-Chih Hsiao Department of Electronic Engineering Kun Shan University
Tainan Taiwan 710 ROC
Abstract mdash In this thesis we present an oscillator mainly composed by a MOS differential amplifier The simulations use H-spice to verify the differential amplifier oscillator under CIC 035μm Si-Ge process parameters We have used discrete devices on bread board to prove such circuit is an oscillator circuit successfully [1-2] Simulations show such an oscillator can work stably from 08 volts to 33 volts supply voltage When supply voltage is close to 33 volts the output frequency will be more than 14 GHz The differential amplifier oscillator can start oscillating at low voltage when supply voltage is only 08 volts and output frequency is about 32 MHz We use FFT (Fast Fourier Transform) diagram to analyze the oscillator and shows the oscillator is with low noise characteristic Finally those simulation results reveal that the oscillator is not only an excellent voltage controlled oscillator (VCO) but also low power consumption
Keyword mdash Differential amplifier VCO FFT
I INTRODUCTION
We use the high input resistance high output resistance and high voltage gain characteristics of MOS differential amplifier [3-5] to create an oscillator Such oscillator is based on differential amplifier have two outputs one output is high voltage state and the other will be in low voltage state We connect one CMOS inverter and two CMOS inverters after two different outputs
It is an asymmetric structure and most output waveform tends to be square waveform The oscillator frequencies are decided by PMOS NMOS resistors MOS transistors and CMOS inverters In this thesis we present a different type oscillator and use simulation results to prove such oscillator is useful easiness and flexibility in design
II CIRCUIT THEOREM
The oscillator is composed of MOS differential amplifier by adding three CMOS inverters as shown in Fig1 A formal differential amplifier needs a constant current source but we use resistor NM1 to replace the constant current source for simplicity According to differential amplifier operation transistor M1 and M2 canrsquot be both off or both in triode state in the same time Transistors M1 M2 will both in saturation state or one is
saturation and the other is off Owing to we canrsquot fabricate two identical transistors M1 and M2 so most conditions are M1 saturation and M2 off or M1 off and M2 saturation
In Fig1 we assume M1 saturation and M2 off so voltage OP1 is in low state and voltage OP2 is in high state In the meanwhile voltage G1 is in high state and voltage G2 is low state After CMOS inverter (INV1) time delay voltage G2 becomes high state to turn on transistor M2 so voltage OP2 changes into low state After CMOS inverters (INV2 INV3) time delay voltage G1 changes into low state to turn off transistor M1
Base on same analysis M2 will be off and M1 will be saturation in the next run After a fixed period M1 and M2 will toggle their states Such onoff continuous switching phenomena will cause oscillation The nodes or transistors status in Fig1 shows in Table1
Fig1 The MOS differential amplifier oscillator
M1 M2 OP1 OP2 G1 G2
State1 Sat Off L H H L
State2 Off Sat H L L H
Table1 Status of transistors and nodes of Fig1
Vcc
PM1 PM1
NM1
OP1 LH
OP2 HL
CMOS INV1 HL
CMOS INV2
M1 M2
CMOS INV3
HL
G1
HL
G2
LH
OUTPUT
Change State
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
III SIMULATION RESULTS
In this thesis we use H-Spice and CIC 035um Si-Ge process parameter to run simulations The discrete devices are MOS transistors M1 (M2) resistors PM1 NM1 and CMOS inverters The channel length of all MOS devices in simulations is fixed and minimum value (l=035μm)
The output waveform under 08 volts supply voltage and oscillation frequency is 32 MHz as shown in Fig2 M1 (or M2) channel width is 15μm Resistor PM1 and NM1 are PMOS and NMOS respectively their gates are connected to ground or VDD to become resistors In Fig1 the channel width of PM1 and NM1 are 10μm 40μm respectively
Fig2 Output waveform under 08 volts
Fig3 shows the oscillator with same condition under 33 volts supply voltage and its output frequency is 14 GHz
Fig3 Output waveform under 33 volts
Fig4 is the typical fast Fourier transform (FFT) diagram of the MOS differential amplifier oscillator Fig4 shows the oscillator with low noise characteristics The highest signal is more than the most other signals about 28 db in Fig4 It means the main oscillation signal is twenty-five (102820=251) times stronger than the most
other signals If the main signal is 15 volts then the most others signals shall be smaller than 006 volts Most conditions are noise signals will become larger as output frequency increases in the MOS differential amplifier oscillator
Fig4 Typical FFT diagram of the MOS differential amplifier oscillator
Fig5 shows resistor NM1 (width=40μm) and transistor Q1 (Q2) unchanged but PM1 channel width is changed from 4μm to 10μm Fig5 reveals larger channel width of PM1 will have higher output frequency because larger channel width has smaller resistance
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
PM1
4u
10u
Fig5 Oscillator output frequencies under different width of PM1 and supply voltages
Fig6 shows resistor PM1 (width=10μm) and transistor M1 (M2) unchanged but NM1 is changed from 20μm to 40μm Fig8 also reveals larger channel width of NM1 will have higher output frequency because larger channel width has resistance M1 (M2) in Fig4 or Fig5 is the same as Fig2 which the channel width of M1 (M2) is 15μm
Fig7 shows resistors PM1 (width=10μm) and NM1 (width=40μm) unchanged but transistor M1 (or M2) channel width is changed The channel widths of transistor M1 (or M2) are 7μm and 15μm respectively
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
NM1
20u
40u
Fig6 Oscillator output frequencies under different width of NM1 and supply voltages
The effect of M1 (or M2) is the same as those effects of resistors PM1 and NM1 on output frequency response The larger channel width transistor has higher output frequency because of higher gm value
08 12 16 2 24 28 32V
0
400
800
1200
1600
MHZ
M1(M2)
7u
15u
Fig7 Oscillator output frequencies under different M1 (M2) and supply voltages
From Fig5 to Fig7 the oscillation frequency increases as supply voltage increases It shows the MOS differential amplifier oscillator is also a voltage controlled oscillator (VCO) The MOS differential amplifier oscillator shows excellent VCO linearity from 08 volts to 33 volts supply voltage as shown in Fig8 We will take use of the nice VCO linearity in our next new phase lock loop (PLL) project
Fig9 shows the power dissipation of MOS differential oscillator under different output frequencies Itrsquos only 10μW under 08 volts supply voltage and output frequency is 32 MHz While supply voltage is 33 volts its output frequency is 14 GHz but power dissipation will be only 225mW
The power dissipation is proportional to the square of output voltages in Fig9 It is consistent with CMOS devices power dissipation PDD = fCV2
DD [6]
05 1 15 2 25 3 35V
0
400
800
1200
1600
MHZ
VCO
Fig8 Voltage controlled oscillator (VCO) characteristics of Fig1
05 1 15 2 25 3 35V
0
5
10
15
20
25
mW
Pdd
Fig9 Oscillator power dissipation under different output voltages
Fig10 shows the layout of the MOS differential amplifier oscillator with 035μm Si-Ge process We have applied CIC process successfully and will receive those chips in this September The applied CIC chip includes three different sizes to get 500MHz 700MHz and 900MHz output frequencies under 20 volts supply voltage respectively
Fig10 Layout of MOS differential amplifier oscillator
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
IV CONCLUSIONS
The MOS differential amplifier oscillator generates square wave not the same as traditional oscillators such as quarts oscillator or ring oscillator can generate sinusoidal waves It is the same as general oscillators that the noises of MOS differential amplifier oscillator are proportional to output frequencies
The MOS differential amplifier oscillator still has three advantages of good linearity voltage controlled (VCO) characteristic low noise and low power dissipation characteristics
In our simulations increase those channel widths of PM1 NM1 or M1 (M2) values can increase output frequency As we know VCO is the leading role of phase lock loop (PLL) circuit Our new project is phase lock loop circuits the MOS differential amplifier oscillator will be the first priority in our PLL VCO block
If we implement those MOS differential amplifier oscillators into IC chips in this September then we will measure output frequencies and power dissipations under different supply voltages We will also get FFT (Fast Fourier Transform) diagram to analyze the noise characteristics When we have those measurement data then we will compare those differences between simulations and experiments
Finally we will find out the limitations of the H-spice on frequency domain power dissipation and noise characters
ACKNOWLEDGEMENTS
The authors would like to thank the National Science Council of Republic of China for their generous and kind support This work was supported by the National Science Council of Republic of China under the contract no NSC93-2218-E-168-002
REFERENCES [1] Cher-Shiung Tsai Chun-Chieh Liao Jia- Ming Wu
Ming-Yi Hsieh Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen and To-Kai Liang ldquoAn Oscillator Design Based on BJT Differential Amplifierrdquo 第三屆微電子技術發展與應用研討會 國立高雄海洋科技大學 94520 2005
[2] Cher-Shiung Tsai Jia-Ming Wu Ming-Yi Hsieh Chun-Chieh Liao Tien-Hung Chang Kwang-Jow Gan Dong-Shong Liang Yaw-Hwang Chen Chia-Hung Chen Chun-Ming Wen ldquoA MOS DIFFERENT- IAL AMPLIFIER OSCILLATORrdquo 16th VLSI DesignCAD Symposium 花蓮美崙大飯店 9489~12 2005
[3] Richard C Jaeger and Travis N Blalock ldquoMicroelectronic Circuit Designrdquo 2nd edition pp 1087-1108 2003
[4] Adel S Sedra and Kenneth C Smith ldquoMicroelectronic Circuitsrdquo 5th edition pp 687-719 2004
[5] Randall L Geiger Phillip E Allen and Noel R Strader ldquoVLSI Design Techniques for Analog and Digital Circuitsrdquo pp 431-454 1990
Adel S Sedra and Kenneth C Smith ldquoMicroelectronic
Circuitsrdquo 5
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Frequency Divider Design Using Negative Differential Resistance Device
Kwang-Jow Gan Chun-Da Tu Chi-Pin Chen Yaw-Hwang Chen Cher-Shiung Tsai Dong-Shong
Liang Wei-Lun Sun Chia-Hung Chen Chun-Ming Wen Chung-Chih Hsiao Shih-Yu Wang and Feng-Chang Chiang
Department of Electronic Engineering Kun Shan University Tainan County 710 Taiwan
Abstract mdash This paper demonstrate a chaos generator
using a R-BJT-NDR device We utilize two bipolar junction transistors and four resistors to construct the R-BJT-NDR device which can show the negative differential resistance (NDR) characteristic in its current-voltage curve by suitably modulating the resistances We will demonstrate a frequency divider using the chaos generator This circuit is consisted of a R-BJT-NDR device an inductor and a capacitor We investigate the effects of the input frequency and the bias voltage on the operation
Index Terms mdash chaos generator R-BJT-NDR device
frequency divider
I INTRODUCTION
The negative differential resistance (NDR) devices are attractive for high-frequency applications and high-speed logic applications [1]-[3] One of the most important features of the NDR devices is their strong nonlinearity A circuit consisting of such nonlinear characteristic often shows the chaos phenomenon In this paper we will design a chaos generator circuit using an R-BJT-NDR device and demonstrate its application to a dynamic frequency divider
The frequency divider is simply made of a R-BJT-NDR device an inductor and a capacitor The R-BJT-NDR device is composed of two bipolar junction transistors and four resistors During suitably arranging the resistances we can obtain the NDR characteristic in its current-voltage (I-V) curve In comparison with the traditional NDR devices such as resonant tunneling diode (RTD) the fabrication of R-BJT-NDR device will be much cheaper and easier than RTD
The applications using nonlinear circuits using the chaotic behavior have been studied intensively in the field of information processing and communication systems [4] In this work we investigate the operating margins of this circuit with respect to input signal frequency and the bias voltage
II R-BJT-NDR DEVICE
We proposed a NDR device that is composed of the bipolar junction transistors (BTJ) and resistors (R) devices We call this device as R-BJT-NDR device Because this device is fully composed of the BJT and R it is suitable for the process of Si-based CMOS or BiCMOS technique This R-BJT-NDR device is composed of two n-p-n transistors and five resistors as shown in Fig 1 During suitably arranging the values of the five resistors we can obtain the I-V curve with NDR characteristics Figure 2 shows the simulated I-V characteristics by Hspice program The electrical parameters are R1=45kΩ R2=53kΩ R3=100kΩ R4=12kΩ and R5=6kΩ
VS
R1
R2
R3
R4
R5Q1
Q2
Fig 1 NDR device is composed of two transistors and five resistances
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
Fig 2 Simulated I-V characteristics by Hspice program
III CHAOS CIRCUIT
Figure 3 shows the configuration of a frequency divider This frequency divider consists of a R-BJT-NDR device an inductor and a capacitor This is a kind of van der Pol oscillator having an input terminal The differential equations determining the systemrsquos behavior are expressed as
LtVtV
dttdi outinL )()()( minus= (1)
out
outNDRLout
CViti
dttdV )()()( minus= (2)
When an external oscillating signal Vin=Vo+ Asin(2πft) is applied this circuit will generate the chaos phenomenon in such nonlinear system Where Vo 2A and f are input bias amplitude and frequency respectively This circuit can output various types of signal patterns including chaos as shown in Fig 4
Fig 3 Configuration of the chaos generator circuit
Fig 4 Simulated waveforms of Vout in a chaotic state
We can also observe the long-period behavior in some regions This is called the bifurcation phenomenon In the bifurcation region the systemrsquos output period is the integer-multiple of the input period It should be noted that the operation frequency range depends on the LC characteristic frequency determined as (12π LC ) Therefore a frequency range close to the cutoff frequency of the R-BJT-NDR device is expected if the appropriate values are chosen for L and C
Figure 5 shows the circuitrsquos output period as a function of the input frequency Figures 5(a)-(b) illustrate the waveforms obtained from the simulation for 2T and 3T under input frequency 15MHz and 18MHz respectively The waveforms show the results for 12 and 13 frequency dividing states respectively
(a)
(b)
Fig 5 (a) a 12 frequency dividing state (b) a 13 frequency dividing state
The frequency dividing operation is explained by the relationship between the charging time of the capacitance Cout and the input period At low input frequency charges are supplied to the output capacitance during a cycle of the input That will be sufficient to switch the R-BJT-NDR device However when the input frequency increases the charges supplied to the capacitance during a cycle decrease due to the shorter period and the increased impedance of the inductor Then the amount of charges supplied to the capacitance is not sufficient to switch the R-BJT-NDR device Therefore two or more cycles are necessary to switch the MOS-BJT-NDR device This causes the frequency dividing operations of 12 13 and so on The phenomena are called period-adding bifurcation Figure 6 shows the circuitrsquos output period as a function of the input frequency The output period increases discontinuously with increasing frequency There will
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997
be a chaos phenomenon existed at the transition
Fig 6 The output period will be a function of input signal
The magnitude of the input bias will affect the results of frequency divider The values of L C and f are fixed at 1mH 10pF and 16MHz respectively Figure 7 shows the dividing ratio as a function of the bias voltage As seen stable 12 13 and 14 dividing operations can be obtained in the simulation results The results demonstrate the dividing ratio can be selected by changing the input bias Figure 8 illustrates the bias regions for the frequency divider Black areas denote the chaos regions
(a)
(b)
(c)
Fig 7 (a) a 12 frequency dividing state (b) a 13 frequency dividing state (b) a 14 frequency dividing state
Fig 8 The dividing ratio as a function of the input bias
IV CONCLUSIONS
We have proposed a NDR-based chaos circuit and its application to a novel frequency divider This chaos circuit is based on the strong nonlinearity of an R-BJT-NDR device We have studied the operation of the frequency divider circuit with respect to the input signal frequency and input bias The frequency dividing operation is based on the bifurcation phenomenon which appears in the chaotic system The dividing ration can be selected by changing the input frequency and input bias
ACKNOWLEDGMENTS
The authors would like to thank the Chip Implementation Center (CIC) for their great effort and assistance in arranging the fabrication of this chip This work was supported by the National Science Council of Republic of China under the contract no NSC94-2215-E-168-001
References
[7] K Maezawa H Matsuzaki M Yamamoto and T Otsuji ldquoHigh-speed and low-power operation of a resonant tunneling logic gate MOBILErdquo IEEE Electron Device Lett vol 19 pp 80-82 1998
[8] A F Gonzalez and P Mazumder ldquoMultiple-valued signed-digit adder using negative differential-resistance devicesrdquo IEEE Trans Comput vol 47 pp 947-959 1998
[9] H L Chan S Mohan P Mazumder and G I Haddad Compact Multiple Valued Multiplexers Using Negative Differential Resistance Devices IEEE J Solid-state Circuits vol 31 pp 1151-1156 1996
[10] M J Ogorzalek Chaos amp Complexity in Nonlinear Electron Circuit World Scientific 1997