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Introduction to Electronics
Operational Amplifiers (OP-AMP)
CHAPTER 8
Ref: Electronic Devices and Circuit Theory
Boylestad
OP-AMP
1. Constant-gain amplifier
2. Voltage summing
3. Voltage buffer
4. Controlled sources
5. Instrumentation circuits
6. Active filters
YTU-Dep. Electrical Eng. / Introduction to Electronics
Common Op-Amp
Applications
OP-AMP
Constant Gain Amplifier
Non-inverting
Amplifier
Inverting
Amplifier
AV  
Rf
R1
YTU-Dep. Electrical Eng. / Introduction to Electronics
AV  1 
Rf
R1
OP-AMP
Voltage Summing
R

R
R
Vo   f V1  f V2  f V3 
R2
R3 
 R1
YTU-Dep. Electrical Eng. / Introduction to Electronics
Voltage Buffer
(Follower)
OP-AMP
VO  Vi
AV 
YTU-Dep. Electrical Eng. / Introduction to
Electronics
VO
1
Vi
OP-AMP
Current-Controlled
Current Source
 Rf 
Vin
Vout  
 Rin 
Vout
Vin

Rf
R1 // R2
Io  
Vin
R1 // R2
 R  R2 

I o  Vin  1
R

R
 1 2
Io  
Vin  R1  R2 


R1  R2 
 R 
I o   I 1  1   kI
 R2 
YTU-Dep. Electrical Eng. / Introduction to Electronics
Vout
V
  in
Rf
Rin
Low-Pass Filter,
First-Order
OP-AMP
The upper cutoff
frequency and voltage
gain are given by:
fOH 
1
2πR1C1
YTU-Dep. Electrical Eng. / Introduction to Electronics
Av  1 
Rf
R1
OP-AMP
Low-Pass Filter,
Second-Order
The roll-off can be made steeper by adding more RC networks.
YTU-Dep. Electrical Eng. / Introduction to Electronics
OP-AMP
High-Pass Filter
fOL 
The cutoff frequency is determined by:
YTU-Dep. Electrical Eng. / Introduction to Electronics
1
2πR1C1
OP-AMP
There are two cutoff frequencies:
upper and lower. They can be
calculated using the same low-pass
cutoff and high-pass cutoff frequency
formulas in the appropriate sections.
YTU-Dep. Electrical Eng. / Introduction to Electronics
Band-Pass Filter
OP-AMP
R1: 2.2 kΩ
Rf: 220 kΩ
Vs: 100 Sinwt (mV)
Vcc: ±12V
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-1
OP-AMP
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-1
OP-AMP
R1: 2.2 kΩ
Rf: 220 kΩ
Vs: 100 Sinwt (mV)
Vcc: ±9V
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-2
OP-AMP
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-2
OP-AMP
R1: 33 kΩ
R2: 22 kΩ
R3: 12 kΩ
Rf: 330 kΩ
V1: +0.2 (V)
V2: -0.5 (V)
V3: +0.8 (V)
Vcc: ±15V
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-3
OP-AMP
YTU-Dep. Electrical Eng. / Introduction to Electronics
Question-3