Electronic Circuits II

Woo-Young Choi

Dept. of Electrical and Electronic Engineering

Yonsei University

Lecture 38: Project #2 Review

Electronic Circuits 2 (20/1) W.-Y. Choi

Lect. 38: Project #2 Review

2

I. Student Presentations

II. Grading Policy

1. 김성령

2. 박준영

3. 여민준

4. 오동현

Electronic Circuits 2 (20/1) W.-Y. Choi

Lect. 38: Project #2 Review

3

Homework: Due 10 am, 6/17

Describe how you could have improved

your design. Minimum one paragraph.

Next (last) lecture on 6/17 Wed.

Lecture 39: Project #3 Design Guide

Lecture 40: Wrap up. Zoom at 11am

(ID: 946 4650 3775)

PRESENTATION

PROJECT 2

2016142179 오동현

Multi-feedback BandPass filter

- It needs only one OPAMP!

< Q = 7.5 >

< Q = 1.5 >

< Q = 7.5 >

< Q = 1.5 >

Schematic Diagram of my OPAMP

Current Mirror & Differential Amp

Simplify Voltage Gain Equation

• Assume 𝑟𝑂𝑁 = 𝑟𝑂𝑃

• 𝐴𝑣 = 𝑔𝑚𝑁 ∗ 𝑟𝑂𝑁||𝑟𝑂𝑃

≅ 𝑔𝑚𝑁 ∗𝑟𝑂𝑁2

= 2𝜇𝑛𝐶𝑜𝑥 ∗𝑊

𝐿∗ 𝐼𝐷 ∗

1

2𝜆𝐼𝐷

=𝜇𝑛𝐶𝑜𝑥

2𝜆2𝐼𝐷∗𝑊

𝐿≅

1

𝜆(𝑉𝐺𝑆−𝑉𝑡ℎ)

λ Simulations(L=2u, W=100u, Vgs=0.6V, 0.75V, 0.9V)

• Purple line :

Id = 1.17 mA

• Yellow line :

Id = 605 uA

• Green line :

Id = 223 uA

Degenerated Common Source stage

• 𝐴𝑣 ≅ −𝑔𝑚𝑃(𝑟𝑜𝑃| 𝑟𝑜𝑁

• When it comes to voltage gain,

almost same as above differential amplifier case.

• It needs low current to take high voltage gain.

Source Follower Stage

• 𝐴𝑣 ≅ 1

• Output Impedance = 1

𝑔𝑚,13|| 𝑟𝑂,15

1

𝑔𝑚,13=

1

2𝜇𝑛𝐶𝑜𝑥∗𝑊

𝐿∗𝐼𝐷

, 𝑟𝑂,15=1

2𝜆𝐼𝐷

• Buffer : It reduces output impedance.

Large 𝐼𝐷 leads to small output impedance.

Bandwidth ( Miller Effect )

•𝑤𝑝~1

𝑅𝑠∗(𝐶1∗𝐴𝑣)

𝐴𝑣 ≅ 𝑔𝑚𝑁(𝑟𝑜𝑁| 𝑟𝑜𝑃 ~1

𝜆(𝑉𝐺𝑆−𝑉𝑡ℎ)(differential amp & CS) 𝐴𝑣 ≅ 1 (SF)

• Large 𝐼𝐷 leads to wide bandwidth

Bandpass filter with designed OPAMP

Result

• Designed

OPAMP

• Ideal

OPAMP

DifferenceAC sweep simulation result of bandpass filter

• Designed

OPAMP

• Ideal

OPAMP

Improvement

Attach bypass filter at output node

The Result of advanced OPAMP

< dvanced designed OPAMP >< original designed OPAMP >

The Drawback of advanced OPAMP

Small Bandwidth

ELECTRONIC CIRCUIT2Name : Seong Ryoung Kim

Major : Business & EEE(Double Major)

INDEX

1. Filter Design with ideal Op-amp

2. Operational Amplifier

3. Filter Design with my Op-amp

1.FILTER WITH IDEAL OP-AMP

- Need to recover the original signal near 300KHz

- band-pass filter or bandpass filter (BPF)

1.FILTER WITH IDEAL OP-AMP

- Because we cannot use inductor, I use inductor simulator instead.

- I don’t use the way to cascade two 1st order filters(Biasing problem, no complex conjugate poles)

1.FILTER WITH IDEAL OP-AMP

- Firstly, choose C1=C2=0.1nF

(This means L=0.002814477 because makes ω0=1

𝐿𝐶=1884955.592rad/s(=2πf0 = 2π ∗ 300000) where L =

R1R3C4R5

𝑅2)

- Secondly, choose R1=R3=R5=5000Ω

- Thirdly, choose R2=4441.32198Ω in order to make L=0.002814477

- Lastly, we can change Q-factor by changing R6

1.FILTER WITH IDEAL OP-AMP

- R6 = 1000, 2000, 5000, 10000, 20000, 50000, 100000

- Q = 0.19, 0.38, 0.94, 1.88, 3.77, 9.42, 18.85

- As Q increases, this filter has sharper frequency

response, smaller 3-dB banwidth(filter BW, not op-

amp), lower peak point

- Works well

1. Frequency response 2. Time domain result

3. Frequency domain result

2. OPERATIONAL AMPLIFIER

Operation Amplifier

- Rin=∞, Rout=0, Av=very large(Vin-=Vin+, I-=I+=0A)

Source Follower

Why do I use OTA and SF to design op-amp?

- OTA has very large gain and Rin=∞, but ithas very large Rout=ron//rop

- SF can have Av=1 and very small Rout

2. OPERATIONAL AMPLIFIER

1 2 3 4

- It is impossible to design the op-amp

satisfying all given specifications at once

- I design source follower by using NMOS

with PMOS load

(This is not a current mirror because of

PMOS load)

- After many attempts, I think it is difficult

to meet the condition of Rout

2. OPERATIONAL AMPLIFIER

1 2 3 4

- Fix Iref=500uA and W1=9.99um in part1

- In part1&4, I maximize W9=100u in

order to satisfy Rout

2. OPERATIONAL AMPLIFIER

Length of gate L1=L2=L3=L4=L5=L6=L7=L8=L9=L10=0.25um

Width of gateW1=9.99um, W2=7.99um, W3=W4=90um, W5=W6=10um, W

7=5.79um, W8=20.134um, W9=100um, W10=80um

Av 40.143dB > 40dB

Bandwidth 102.365MHz > 100MHz

Output impedanc

e90.627Ω< 100 Ω @DC

Power Consumpti

on2.959mW(=about 1.480*2mW) < 10mW

1. Gain & BW 2. Power

3. Rout

Summary of my design result

3. FILTER DESIGN WITH MY OP-AMP

- R6 = 1000, 2000, 5000, 10000, 20000, 50000, 100000

- Q = 0.19, 0.38, 0.94, 1.88, 3.77, 9.42, 18.85

- As Q increases, this filter has sharper frequency

response, smaller 3-dB banwidth(filter BW, not op-

amp), lower peak point

- At low frequencies, the frequency response has flat

shape different from the ideal filter with ideal op-

amp

1. Frequency response

3. FILTER DESIGN WITH MY OP-AMP2. Time domain result 3. Frequency domain result

- My filter restores original signal from corrupted signal well at high frequencies

- But it has the limitation in that it cannot filter low frequencies

- This is the difference between the ideal filter and my designed filter

3. FILTER DESIGN WITH MY OP-AMP

Ideal Op-apm My designed Op-amp

- Rin=∞- Rout=0

- Av=very large(106->120dB)(Vin-=Vin+, I-=I+=0A)

- Rin=∞- Rout=90.627Ω- Av=40.143dB

- Although I lower the Rout to improve my

designed filter, I cannot get a desired

result

- So I improve my filter by enlarging gain

3. FILTER DESIGN WITH MY OP-AMP1. Gain & BW(Trade off relationship by Miller effect)

2. Rout

- I don’t change W because I don’t want

to change the physical properties of the

all MOSFET

- I increase gain(it lowers BW) by

lowering Iref

(Lowering Iref means lowering Id2&Id7.

As a result it means increasing gain.)

3. FILTER DESIGN WITH MY OP-AMP

- I improved my designed filter by increasing gain

- This improved filter can filter low frequencies

- But there is a limitation in that my designed filter

has flat shape of frequency response at low

frequencies

3. FILTER DESIGN WITH MY OP-AMP

Initial designed op-amp(R6=5000Ω) Improved designed op-amp (R6=5000Ω)

Increasing

gain

Thank you!

-Design Report [50]

1. Filter Design with ideal Op-amp [10]

(1) What type of a second-order filter is needed for restoring the original signal

from the corrupted signal? What is its characteristics? Explain why. [5]

- 구체적인 스펙을 제시해야 함. 예) 밴드패스 필터에서 280kHz - 320kHz

- 구체적인 구조를 제시해야 함. 예) BPF

- Noise가 있는 signal을 time domain과 frequency 도메인에서 분석 후,

신호 성분이 300kHz, 그 외에 넓은 지역에서 WGN이 있다는 사실을 명시

(2) Implement the filter in PSPICE using passive circuit elements (R can C) and up

to two ideal op-amps. Shows the time- and frequency-domain characteristics

of the signal restored with your ideal filter. [5]

- 만든 스키메틱 첨부, 설명( 전달함수 식 유도)

- AC Sweep , Transient, FFT 그래프 모두 첨부, 간단한 분석

- 그래프 셋업 첨부

- Ideal filter를 썼을 경우 얼마나 신호가 복구가 잘 되었는가.

2. Operational Amplifier [20]

(1) Determine the structure of your Op-amp. [5]

(Consider requirements to operate as an Op-amp.)

Op amp의 조건. 높은 게인, 넓은 대역폭, 작은 아웃풋 임피던스 이를 만족시키기 위한

각각의 구조를 대입. 예) 높은 게인을 위해 CS Amp, 그리고 작은 아웃풋 임피던스를

위해 SF를 차례대로 연결한 3-stage opamp를 디자인하였다.

(2) Obtain the gain of the Op-amp. [5]

(Your Design, measurement set-up & result, all contetnts should be included.)

- 각각 on/off로 채점 조건 만족시 4점, 셋업 미첨부시 1점감점

(3) Obtain the Bandwidth of the Op-amp. [5]

(Your Design, measurement set-up & result, all contetnts should be included.)

- 각각 on/off로 채점 조건 만족시 4점, 셋업 미첨부시 1점감점

(4) Calculate the power consumption of your design. [5]

(Any current source for mirroring should be excluded in your calculation.)

- 각각 on/off로 채점 조건 만족시 4점, 셋업 미첨부시 1점감점

※ output impedance 미첨부시 4점 감점.

3. Filter Design with your Op-amp [20]

(1) Design the filter using the Op-amp you designed in Section 2. Show the

resulting characteristics (time and frequency domain) of the restored signal [5]

(All contents about filtered signal should be included: frequency response, transient

simulation result, and its FFT result and its set-up for measurement. )

- 이전 step까지 잘 진행되어 합쳤을 것을 전제로 신호가 완벽히 복원된 경우 5점

그렇지 않고 조금 미흡한 경우 4점

(2) Discuss the difference between the results you obtained in Section 1 with

ideal op-amps and that with your op-amp. [15]

(Explain the weakness of your op-amp and how to overcome)

- 기본 5점

- ideal과 my own을 비교하면 8점

- 개선사항을 언급시 10점

- 구체적인 개선방법 제시할 경우 12점

- 이를 시행하여 시간축 상 개선이 조금이라도 보이면 14점

- 이를 시행하여 시간축 상 개선이 분명히 보이면 15점

.