4/8/2018 [1] PE Prof. Mor M. Peretz Analog Electronic Circuits - - PDF document

4/8/2018 1

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [1]

PE M I C

BGU

Analog Electronic Circuits

• Prof. Mor M. Peretz

The Center for Power Electronics and Mixed-Signal IC Department of Electrical and Computer Engineering Ben-Gurion University of the Negev, ISRAEL Emails: morp@bgu.ac.il Website: http://www.ee.bgu.ac.il/~pemic http://www.ee.bgu.ac.il/~analog

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [2]

PE M I C

BGU

Lesson #3 Outline

• Dynamic limitations of OpAmps

– Open-loop response – Gain-Bandwidth product

• Drawing AOL , 1/β, βAOL
• Closed-loop response

– The GBW trade-off

• Resistive circuits
• Frequency-dependent circuits
• Transient response

– Slew-rate

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [3]

PE M I C

BGU

Open-loop response

LM324 (Texas Instruments, National)

+ (V+ - V-) A1

V+ V- Req Ceq

+

Vout1 A2 Vout1 Vout2

+

Vout

Ceq Vout1 gm1 Req

IN- Vout Q1 Q2 Q3 Q4 VCC VEE iB IN+ gm1 iout1 A1=gm1Req Req A2 1 Ceq CC

+

• A1

A2 1

4/8/2018 2

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [4]

PE M I C

BGU

Open-loop response

+ (V+ - V-) A1

V+ V- Req Ceq

+

Vout1 A2 Vout1 Vout2

+

Vout Ceq Vout1 gm1 Req

𝐵𝑃𝑀 =

𝐵 1+𝑘 𝑔

𝑔𝐷

A [dB] f [Hz] 2π ReqCeq 1

• 20 [dB/dec]

A1A2A3=AOL fc funity

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [5]

PE M I C

BGU

Gain-Bandwidth Product - GBW

A [dB] f [Hz] 2π ReqCeq 1

• 20 [dB/dec]

A1A2A3=AOL fc funity 𝐵𝐷𝑀 = 𝐻 𝐵𝑃𝑀 1 + 𝛾𝐵𝑃𝑀 𝛾 = 1, 𝐻 = 1 𝐵𝐷𝑀 = 𝐵𝑃𝑀 1 + 𝐵𝑃𝑀 𝐻𝐶𝑋 = 𝐵𝑃𝑀𝑔

𝑑 = 𝑔 𝑣𝑜𝑗𝑢𝑧

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [6]

PE M I C

BGU

• The system is unstable if the characteristic equation {1+βAOL(s)} has roots in

the right half of the complex plane

• Nyquist criterion is a test for location of {1+βAOL(s)} roots
• Nyquist criterion can be viewed on the frequency domain (Bode)

Loop-Gain Nyquist Criterion

𝐵𝐷𝑀 = 𝐻 𝑡 𝐵𝑃𝑀 𝑡 1 + 𝛾𝐵𝑃𝑀 𝑡

4/8/2018 3

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [7]

PE M I C

BGU

Loop-gain on the frequency domain

f f



 [dB] +180 |LG|

   

f A f  In negative feedback systems At f0 ) 180 ( 180

• 

  +-

G AOL β Xin X’in Xe Xout Xf

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [8]

PE M I C

BGU

f f



 [dB]

• 180

A 

m

 1 A  

• 1

| A |

• 1

| A | m

180 ) 180 (        

   

Bode plot Phase margin

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [9]

PE M I C

BGU

Graphical representation of βAOL conventional method

 Tedious – need to re-plot BA  Analysis (not design) oriented  Requires iterations

A

] dB [ B

3

f

B

] dB [ A

2

f

1

f ] Hz [ f ] Hz [ f ] dB [ AB

AB

3

f

2

f

1

f ] Hz [ f

4/8/2018 4

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [10]

PE M I C

BGU

] dB [ A ] Hz [ fo

A 1  BA BA

1 BA  1 BA  BA ) f ( LG  B 1

Graphical Representation of βAOL

20log(BA) B 1 20log A 20log   1 A B B 1 20log 20logA    

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [11]

PE M I C

BGU

Closed-loop response Non-inverting Amp

• +

Vin VOUT R2 R1 Ve 𝐻 =1 1 𝛾 = 𝑆1 + 𝑆2 𝑆2

𝐻𝐶𝑋 = 𝐵0𝑔

𝑑 = 𝑔 𝑣𝑜𝑗𝑢𝑧

A0_2 A0_3 [dB] f [Hz] AOL 1/β1 1/β3 1/β2 A0_1 fc_1 fc_2 fc_3 funity

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [12]

PE M I C

BGU

Closed-loop response Inverting Amp

𝐻𝐶𝑋 = 𝐵0𝑔

𝑑 = 𝑔 𝑣𝑜𝑗𝑢𝑧

𝐻 = 𝑆1 𝑆1 + 𝑆2

+

• Vin

VOUT R2 R1 Ve

1 𝛾 = 𝑆1 + 𝑆2 𝑆2

A0 [dB] f [Hz] AOL 1/β fc funity G

4/8/2018 5

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [13]

PE M I C

BGU

Closed-loop response Integrator

𝐻𝐶𝑋 = 𝐵0𝑔

𝑑 = 𝑔 𝑣𝑜𝑗𝑢𝑧

𝐻 = 1 𝑡𝐷𝑆 + 1 1 𝛾 = 𝑡𝐷𝑆 + 1 𝑡𝐷𝑆

+

• Vin

VOUT R C VƐ

[dB] f [Hz] AOL 1/β G

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [14]

PE M I C

BGU

Transient response Rise-time (ideal)

+

• Vin

VOUT R Ve

+

Req Ceq Ceq I Req 0.9Vf

t

Vf tr 0.1Vf

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [15]

PE M I C

BGU

4/8/2018 6

• Prof. Mor M. Peretz

Analog Electronic Circuits 361-1-3671 THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY [16]

PE M I C

BGU