EE 332
DEVICES AND CIRCUITS II
Chapter 1
Concepts and limitations of OPAMP-based
circuits
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1
Chapter Goals
Understanding behavior and characteristics of ideal
operational amplifiers (Opamp)
Understand many kinds of Opamp circuits including
inverting, noninverting, summing, subtraction,
differentiator, integrator, PI circuits…
Provide an introduction to active filters
Chap 1 - 2
Chap 1 - 3
Chap 1 - 4
Chap 1 - 5
Chap 1 - 6
Opamp LM 741
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Opamp LM 741
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Opamp = Operational Amplifier
Characteristics of ideal Opamp:
+ High input impedance, for example: 1012 Ω
+ High open-loop voltage gain, for example: (104-106)
+ Low output impedance, for example: (10-100) Ω
+ Limited bandwidth, for example: 14MHz
All available opamps in the market nowadays are
considered ideal opamps
Chap 1 - 9
The Amplifier with high input resistance (Rin)
Vout = ? Vin
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The Amplifier with high input resistance (Rin)
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The Summing Amplifier
Vout = ?? Vin1; Vin2; ...Vinn
Chap 1 - 12
The Summing Amplifier
Chap 1 - 13
The Subtraction Amplifier
RN
RP

a
R1
R2
Vout = ? Vin1, Vin2
Chap 1 - 14
The Subtraction Amplifier
Chap 1 - 15
The Subtraction Amplifier with Rin  
Vout = ? Vin1, Vin2
Chap 1 - 16
The Subtraction Amplifier with Rin  
 v3



 v3

 vin1 vin 2  vin1  vin1


0
R3
R1
R2
 vin 2 vout  vin 2 vin1  vin 2


0
R3
R2
R1
R1  2 R3
vout  (1  R2
)(vin2 - vin1)
R1 R3
Chap 1 - 17
Example 1
Ri = R1 = R3 = 10k, R2 = 100K.
Find Av=vout/vin.
Chap 1 - 18
Example 2
VR = 50k; VCC =  12V; R1 = 20k; R2 = 250k; R3 =
5k; R4 = R5 = 15k; R6 = 165k;
Chap 1 - 19
The inverting integrator
Vout = ? Vin
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The inverting integrator
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The Bode plot of integrator
has slope
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The integrator of Summing
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The integrator of Subtraction
Vout = ? Vin1, Vin2
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The integrator of Subtraction
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The inverting Differentiator
Vout = ? Vin
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The inverting Differentiator
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The Proportional Integrated amplifier (PI)
Vout = ? Vin
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The Proportional Integrated amplifier (PI)
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The bode plot of PI amplifier
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The active Low-Pass Filter (LPF)
Chap 1 - 31
Chap 1 - 32
The Active High-Pass Filter (HPF)
Chap 1 - 33
End of chapter 1
Chap 1 - 34