1_Basic Introduction to Operational Amplifiers.pdf

Introduction to Operational Amplifiers

1. Basic op-amp operation and application circuits

2. Op-Amp Symbol
Op-amp is a contraction of ‘Operational- amplifier’
A device used in circuits that perform
mathematical operations on signals

3. Pin Names

4. Physical Form (through- hole)

5. Pin Layout (typical)

6. Device Characteristics
Very high input impedance
Very low output impedance
Very high gain
Differential inputs

7. Op-Amp Equivalent Circuit

8. Summary of Properties

9. Basic Application Circuits
Analog signal processing
Analog/digital conversion (ADCs and DACs)
Interfacing to sensors (signal conditioning)

10. Feedback
For analog applications negative feedback is applied to
the op-amp (‘closed loop’ operation)
Feedback affects the overall properties of the circuit
Gain
Input impedance
Output impedance
Bandwidth

11. The Inverting Amplifier
What is the gain?
U3
LM741CN
3
2
4
7
6
5 1
R1
R2
R3
Input
Output

12. The Non- inverting Amplifier
What is the gain?
U3
LM741CN
3
2
4
7
6
5 1
R1 R2
R3Input
Output

13. Voltage Follower Implementation

14. Voltage Follower (cont.)
Why use a circuit where the input and
output are the same?

15. Ans:
Impedance matching
‘Buffering’ between circuit stages
Driving a low impedance load (higher current)

16. The Differential Amplifier

17. Instrumentation Amplifier (Basic)