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3/25/2018
1
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[1]PEMICBGU
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: [email protected]
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]PEMICBGU
Lesson #2
Outline• Basic OpAmp circuits
– Summing, difference, integrator, differentiator
• Basic feedback
– Feedback definition
– OpAmp as feedback system
• Non-inverting and inverting cases
• Static limitations
– DC errors
• Bias current, Offset voltage
– Correction for offsets
– Output voltage swing, input voltage range
• Dynamic limitations
– Open-loop response
– Gain-Bandwidth product
3/25/2018
2
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[3]PEMICBGU
OpAmp characteristics
+(V+ - V-) A
VOUTV+
V-
+
-
Ideal OpAmp primary features:
• Differential inputs
• Output product as function inputs (V+ - V-) A
A=A1A2A3
• Infinite gain A→∞
• Infinite Bandwidth BW→∞
• Infinite input resistance Rin→∞
• Zero output resistance Rout→ 0
+
-A1 A2 1
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[4]PEMICBGU
Non-inverting Amp
-
+
Vin
VOUT
Z2
Z1
Ve
Vf
+
-
Vin
VOUT
R
Ve
3/25/2018
3
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[5]PEMICBGU
Summing Amp
+
-V1
VOUT
Zin1
Z1
VƐ
Zin2V2 𝑉𝑜𝑢𝑡 = − 𝑉1
𝑍1
𝑍𝑖𝑛1+𝑉2
𝑍1
𝑍𝑖𝑛2
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[6]PEMICBGU
Difference Amp
+
-V1
VOUT
R2
R1
VƐ V2
R3
R4
𝑉𝑜𝑢𝑡_1 = −𝑉1
𝑅1
𝑅2
𝑉𝑜𝑢𝑡_2 = 𝑉2
𝑅4
𝑅3 + 𝑅41 +
𝑅1
𝑅2
𝑅2
𝑅1=
𝑅3
𝑅4
𝑉𝑜𝑢𝑡 =𝑅1
𝑅2𝑉2 − 𝑉1
3/25/2018
4
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[7]PEMICBGU
Feedback forces zero error state
+
-Vin
VOUT
R2
R1
Ve
R3
R4
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[8]PEMICBGU
Integrator Amp
+
-Vin
VOUT
R
C
VƐ
𝑉𝑜𝑢𝑡 =1
𝑆𝐶/
1
𝑅𝑉𝑖𝑛 =
1
𝑆𝐶𝑅𝑉𝑖𝑛
3/25/2018
5
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[9]PEMICBGU
Differentiator Amp
+
-Vin
VOUT
R
C
VƐ
𝑉𝑜𝑢𝑡 = 𝑆𝐶/𝑅𝑉𝑖𝑛 = 𝑆𝐶𝑅 𝑉𝑖𝑛
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[10]PEMICBGU
Voltage reference by OpAmp (Bandgap)
3/25/2018
6
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[11]PEMICBGU
Current source by OpAmp
-
+Vref
R
Iout
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[12]PEMICBGU
Negative Feedback
+-
G AOL
β
XinX’in Xe
Xout
Xf
𝐴𝑂𝐿 =𝑋𝑜𝑢𝑡
𝑋𝑒
𝐺 = 𝑋𝑖𝑛
′
𝑋𝑖𝑛 𝑋𝑜𝑢𝑡=0
= 𝑋𝑒
𝑋𝑖𝑛 𝑋𝑜𝑢𝑡=0
𝛽 = 𝑋𝑓
𝑋𝑜𝑢𝑡 𝑋𝑖𝑛=0
= 𝑋𝑒
𝑋𝑜𝑢𝑡 𝑋𝑖𝑛=0
𝐴𝐶𝐿 =𝑋𝑜𝑢𝑡
𝑋𝑖𝑛= 𝐺
𝐴𝑂𝐿
1 + 𝛽𝐴𝑂𝐿
𝐴𝐶𝐿𝛽𝐴𝑂𝐿≫1
=𝐺
𝛽
𝐴𝐶𝐿𝛽𝐴𝑂𝐿≪1
= 𝐺𝐴𝑂𝐿
3/25/2018
7
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[13]PEMICBGU
Feedback
Non-inverting Amp
-
+
Vin
VOUT
Z2
Z1
Ve
Vf
+-
AOL
β
Vin VeVout
Vf
𝐺 = 𝑉𝑒
𝑉𝑖𝑛 𝑉𝑜𝑢𝑡=0=1
𝛽 = 𝑉𝑒
𝑉𝑜𝑢𝑡 𝑉𝑖𝑛=0
=𝑍2
𝑍1 + 𝑍2
𝐴𝐶𝐿 𝛽𝐴𝑂𝐿≫1 =𝐺
𝛽=
1𝑍2
𝑍1+𝑍2
=𝑍1+𝑍2
𝑍2= 1 +
𝑍1
𝑍2
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[14]PEMICBGU
Feedback
Inverting Amp
𝐺 = 𝑉𝑒
𝑉𝑖𝑛 𝑉𝑜𝑢𝑡=0
=𝑍1
𝑍1 + 𝑍2
𝛽 = 𝑉𝑒
𝑉𝑜𝑢𝑡 𝑉𝑖𝑛=0
=𝑍2
𝑍1 + 𝑍2
+-
G AOL
β
VinV’in Ve
Vout
Vf
+
-Vin
VOUT
Z2
Z1
Ve
𝐴𝐶𝐿 𝛽𝐴𝑂𝐿≫1 =𝐺
𝛽= −
𝑍1𝑍1+𝑍2
𝑍2𝑍1+𝑍2
= −𝑍1
𝑍2
3/25/2018
8
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[15]PEMICBGU
Static limitations
Input stage
+
-
Vout
VEE
VCC
IN- IN+
Vout
Q1 Q2
Q3 Q4
VCC
VEE
iout
iB
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[16]PEMICBGU
Bias current
Non-inverting Amp
-
+
Vin VOUT
R2
R1
Ve
Vf ib-
ib+
3/25/2018
9
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[17]PEMICBGU
Bias current
Inverting Amp
+
-Vin
VOUT
R2
R1
Ve
ib+
ib-
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[18]PEMICBGU
Bias current
Correction
+
-Vin
VOUT
R2
R1
Ve
ib+
ib-
-
+Vin
VOUT
R2
R1
Ve
ib-
ib+
3/25/2018
10
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[19]PEMICBGU
Bias current
Input bias cancellation
OP-07 (Analog Devices)
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[20]PEMICBGU
Bias current
Low bias input
TL08x (Texas Instruments)
3/25/2018
11
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[21]PEMICBGU
Static limitations
Offset voltage
+
-
Vout
VEE
VCC 𝛽 = 𝑉𝑒
𝑉𝑜𝑢𝑡 𝑉𝑖𝑛=0
=𝑍2
𝑍1 + 𝑍2
𝑖𝑜𝑢𝑡 = 𝑔𝑚 𝑉+ − 𝑉−
𝑖𝐶1+ 𝑖𝐶2 = 𝑖𝐵
𝑖𝐶 = 𝐼𝑆𝑒𝑉𝐵𝐸𝑉𝑇
𝑖𝐶1
𝑖𝐶2=
𝐼𝑆1
𝐼𝑆2𝑒
𝑉𝐵𝐸1−𝑉𝐵𝐸2𝑉𝑇
𝐼𝑆1= 𝐼𝑆2, 𝑉𝐸1 = 𝑉𝐸2 ;𝑖𝐶1
𝑖𝐶2= 𝑒
𝑉+−𝑉−𝑉𝑇
IN- IN+
Vout
Q1 Q2
Q3 Q4
VCC
VEE
iout
iB
𝑔𝑚 =𝑖𝐵
2𝑉𝑇
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[22]PEMICBGU
Offset voltage
-
+
VinVOUT
R2
R1
Ve
VOS
+
-Vin
VOUT
R2
R1
Ve
VOS
3/25/2018
12
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[23]PEMICBGU
Offset voltage
Correction
IN- IN+
Vout
Q1 Q2
Q3 Q4
VCC
VEE
iout
iB
+
-
Vout
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[24]PEMICBGU
Maximum ratings (Basic)
IN- IN+
Vout
Q1 Q2
Q3 Q4
VCC
VEE
iout
iB
Q1
VEE
Q2
VCC
OUT
IN- IN+
3/25/2018
13
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[25]PEMICBGU
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
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[26]PEMICBGU
Open-loop response
+(V+ - V-) A1
V+
V-
Req
Ceq
+Vout1 A2
Vout1 Vout2
+
Vout
Ceq
Vout1
gm1 Req
𝐴𝑂𝐿 =𝐴
1+𝑗𝑓
𝑓𝐶
A [dB]
f [Hz]
2π ReqCeq
1
-20 [dB/dec]
A1A2A3
fc
3/25/2018
14
Prof. Mor M. Peretz Analog Electronic Circuits 361-1-3671
THE CENTER FOR POWER ELECTRONICS AND MIXED-SIGNAL IC, BEN-GURION UNIVERSITY
[27]PEMICBGU
Gain-Bandwidth Product - GBW
A [dB]
f [Hz]
2π ReqCeq
1
-20 [dB/dec]
A1A2A3
fc
funity
𝐴𝐶𝐿 = 𝐺𝐴𝑂𝐿
1 + 𝛽𝐴𝑂𝐿
𝛽 = 1, 𝐺 = 1
𝐴𝐶𝐿 =𝐴𝑂𝐿
1 + 𝐴𝑂𝐿
𝐺𝐵𝑊 = 𝑓𝑢𝑛𝑖𝑡𝑦
