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Ching-Yuan Yang
National Chung Hsing UniversityDepartment of Electrical Engineering
Introduction to Electronics
Read Chapter 1 & Chapter 2, Section 2.1-2.3
Sedra/Smith’s Microelectronic Circuits
1-1 Ching-Yuan Yang / EE, NCHUElectronics (I)
Electronic Circuits (一)
Prof. Ching-Yuan Yang (楊清淵)
Room 823 Electrical Engineering Building
Email: [email protected]
Website: http://web.nchu.edu.tw/~analog/
Text book: Microelectronic Circuits, 5e, by Sedra/Smith (Oxford 2004)
Course Assessment:
15% Assignments
80% Three Term examinations
5% Other
Course Contents:
Introduction (Ch1, Ch2)
Diodes (Ch3)
Bipolar Junction Transistors (Ch5)
MOS Field-Effect Transistors (Ch4)
1-2 Ching-Yuan Yang / EE, NCHUElectronics (I)
Brief history of electronics
Identification of the electron by J.J. Thomson late in the 19th
century and the measurement of its electric charge by Robert A. Millikan in 1909.
Invention of vacuum tube in 1906 by Lee De Forest
Invention of the transistor in 1947 by John Bardeen, Walter H. Brattain, and William B. Shockley of the Bell Lab.
Invention of integrated circuits (IC) independently by Jack Kilbyof Texas Instruments in 1958 and by Jean Hoerni and Robert Noyce of Fairchild Semiconductor in 1959.
Discover of Moore's law (1965): The number of transistors per silicon chip doubles every 18 months.
1-3 Ching-Yuan Yang / EE, NCHUElectronics (I)
Examples of analog IC
−Gyroscope systemSingle-chip gyroscopic sensor
Tiny
Robust
Lower power
Angular-rate-to-voltage transducer
−BiCMOS process
−Chip area: 3mm × 3mm
−Power: 30mW @ 5V
−Product by Analog Devices, USA
1-4 Ching-Yuan Yang / EE, NCHUElectronics (I)
Signal source
A fundamental function of electronic circuits is to process signals.
Signals contain information about a variety of things and activities in our physical world. Example - information about weather: air temperature, humidity, pressure, etc.
To process the information by electronic systems, the signal must first be converted into an electric signal, i.e., a voltage or current, by a device called “transducer”.
A electric signal source can be represented by either (a) Thévenin or (b) Norton forms:
1-5 Ching-Yuan Yang / EE, NCHUElectronics (I)
Analog and digital signals
represents the physical signal in the world around us. A analog signal is continuous both in time and magnitude.
is a sequence of numbers. A digital signal is discrete both in time and amplitude.
Analog signal :
Digital signal :
Discretized or digitized signal :
Digital signal can be converted from analog signal. As shown in Figure, at equal intervals along the time axis, the analog signal is measured (sampled).
1-6 Ching-Yuan Yang / EE, NCHUElectronics (I)
Analog and digital signals
Binary number system is most commonly used to represent the discretizedsignal because it results in the simplest possible digital signals and circuits.
The digital signals in binary systems need have only two voltage levels, which can be labeled low and high (0 and 1). If we use N binary digits (bits) to represent each sample of the analog signal, then the digitized sample value can be expressed as
where b0, b1, …, bN-1 , denote the N bits and have values of 0 or 1,
b0 = least significant bit (LSB),
bN-1 = most significant bit (MSB).
For example the D corresponding to 15 is 1+2+4+8 , or (1 1 1 1).
0 1 10 1 12 2 2N
ND b b b −−= + + +
1-7 Ching-Yuan Yang / EE, NCHUElectronics (I)
Introduction to amplifiers
Amplifier Gains
Ov
I
vA
v≡Voltage gain ( ) (V/V)
Oi
I
iA
i≡Current gain ( ) (A/A)
L O Op
I I I
P v iA
P v i≡ =
load power ( )Power gain ( ) (W/W)
input power ( )
Gains defined above are ratios of similarly dimensioned quantities and thus are dimensionless numbers.Historically, electronic engineers are used to express gain with a logarithmic measure as
v
i
p
A
A
A
=
=
=
Voltage gain in decibels 20 log dB
Current gain in decibels 20 log dB
Power gain in decibels 10 log dB
Power is related to voltage (or current) squared.
1-8 Ching-Yuan Yang / EE, NCHUElectronics (I)
Introduction to amplifiers (cont’)
dc power delivered to the amplifier:
Pdc = V1I1 + V2I2
If the power dissipated in the amplifier circuit is denoted Pdissipated, the power-balance equation for the amplifier can be written as
Pdc + PI = PL + Pdissipated
PI : the power drawn from the signal source
PL : the power delivered to the load
It measures how much dc power is converted to the power on the load.
Amplifier power supply
Amplifier efficiency
LP
Pη ≡ ×
dc
100
1-9 Ching-Yuan Yang / EE, NCHUElectronics (I)
Introduction to amplifiers (cont’)
Amplifier saturation
In order to avoid distorting the output signal waveform, the input signal swing must be kept within the linear range of operation:
Iv v
L Lv
A A− +≤ ≤
1-10 Ching-Yuan Yang / EE, NCHUElectronics (I)
Introduction to amplifiers (cont’)
Concept of biasing
Practically, an amplifier also exhibits nonlinearities of various magnitudes.
A simple technique for obtaining linear amplification is to biasthe circuit to operate at a point near the middle of the transfer characteristic. The point Q is known as the quiescent point, the dc bias point, or simply the operating point.
( ) ( )
( ) ( )I I i
O O o
v t V v t
v t V v t
= +
= +
( ) ( )o v iv t A v t=
Ov
I
dvA
Qdv=
at
1-11 Ching-Yuan Yang / EE, NCHUElectronics (I)
IEEE symbol convention
Total instantaneous signal: iCIncremental instantaneous signal: icDC/Biasing level: IC
Incremental peak level: Ic
C C ci I i= +
1-12 Ching-Yuan Yang / EE, NCHUElectronics (I)
Circuit models for amplifiers
1-13 Ching-Yuan Yang / EE, NCHUElectronics (I)
Digital logic inverter
The logic inverter is the most basic element in digital circuits.
Noise Margin for high inputs:
Noise Margin for low inputs:
The VTC of an ideal inverter:
NMH = VOH − VIH
NML = VIL − VOL
Voltage transfer characteristic (VTC):
1-14 Ching-Yuan Yang / EE, NCHUElectronics (I)
Digital logic inverter – implementation
Basis of transistor-transistor logic (TTL)
Transistor switches
1-15 Ching-Yuan Yang / EE, NCHUElectronics (I)
Digital logic inverter – implementation (cont’)
No static current flow
Basis of CMOS logic
Complementary switches
1-16 Ching-Yuan Yang / EE, NCHUElectronics (I)
Digital logic inverter – implementation (cont’)
The fastest inverter
Complementary outputs
Basis of Emitter-Coupled Logic (ECL)
Current steering
1-17 Ching-Yuan Yang / EE, NCHUElectronics (I)
Operational amplifier
Circuit symbol:
Equivalent circuit of the ideal op amp:
Infinite input impedance
Zero output impedance
Zero common-mode gain
Infinite open loop gain A
Infinite bandwidth
1-18 Ching-Yuan Yang / EE, NCHUElectronics (I)
Operational amplifier (cont’)
Inverting closed-loop configuration:
1-19 Ching-Yuan Yang / EE, NCHUElectronics (I)
Operational amplifier (cont’)
Noninverting closed-loop configuration:
1-20 Ching-Yuan Yang / EE, NCHUElectronics (I)
Operational amplifier (cont’)
Voltage follower:
1-21 Ching-Yuan Yang / EE, NCHUElectronics (I)
Circuit simulation using SPICE
SPICE: Simulation Program with Integrated Circuited Emphasis
An open-source program developed by the U.C. Berkeley (1970s)
Computer programs to simulate the operation of electronic circuits
PSpice is a commercial PC version available from Cadence
Others: ISPice, HSpice, …
It is not our objectively to teach how SPICE works nor the intricacies of using it effectively.
Our objective is twofold:
To describe the models that are used by SPICE to represent the various electronic devices
To illustrate how useful SPICE can be in investigating circuit operation
In this course, ….
SPICE