1. ECE 3302 Fundamentals of Electrical Engineering
Presentation 21
Operational Amplifiers

2. Operational Amplifier
Integrated Circuit

3. The Ideal Operational Amplifier
Inverting Input v− vo
Non-inverting Input v+
A(v+ − v−)
Circuit Model v− vo v+
Circuit Symbol

4. The Ideal Operational Amplifier

5. The Ideal Operational Amplifier
+Vcc
Vcc
vout
Vcc v1 v2
−Vcc
Op-Amp with Double-ended Power Supply

6. The Ideal Operational Amplifier

7. Non-inverting Amplifier Configuration
The output voltage is controlled by using negative feedback. R2 R1
vout
vin

8. Non-inverting Amplifier Configuration
vout
vin v+
A(v+ − v−)

9. Non-inverting Amplifier Configuration
vout
vin
𝑣 𝑜𝑢𝑡 𝑣 𝑖𝑛 =1+ 𝑅 2 𝑅 1

10. Inverting Amplifier Configuration
The output voltage is controlled by using negative feedback. R2 R1
vin
vout

11. Inverting Amplifier Configuration
vin v−
vout v+
A(v+ − v−)

12. Inverting Amplifier Configuration
vin
vout
𝑣 𝑜𝑢𝑡 𝑣 𝑖𝑛 =− 𝑅 2 𝑅 1

13. Linear Operational Amplifier Circuits with Negative Feedback
Op amp circuits with negative feedback may be analyzed by applying two facts.
1. The input resistance of the op amp is infinite; therefore the input current is zero.
2. There is zero voltage difference (a virtual short-circuit) between the input pins, therefore v+ = v−.

14. Inverting Amplifier R2 R1
vin
vout

15. Non-inverting Amplifier
vout
vin

16. Voltage Follower (Unity Gain Buffer)
vout
vin
𝑣 𝑜𝑢𝑡 𝑣 𝑖𝑛 =1+ 𝑅 2 𝑅 1
Let R2 → 0 and R1 →∞

17. Voltage Follower (Unity Gain Buffer)
vout
vin
𝑣 𝑜𝑢𝑡 𝑣 𝑖𝑛 =1
𝑣 𝑜𝑢𝑡 = 𝑣 𝑖𝑛

18. Summing Amplifier R1 Rf v1 R2 v2
vout R3 v3

19. Difference Amplifier R1 R2 v1
vout R1 R2 v2

20. Offset Voltage adjustmentR2
+Vcc R1
vin
vout RP
voff
−Vcc

21. Offset Voltage adjustmentR2
+Vcc R1 RP
vout
voff
vin
voff
−Vcc

22. Instrumentation Amplifier
vo1 v1 R R va R
vout Rg R R R vb v2
vo2

23. Cascaded Operational Amplifiers
vin
vout

24. Operational Amplifier Parameters

25. Operational Amplifier Parameters

26. Operational Amplifier Parameters

27. The 741 Operational Amplifier

28. The 741 Operational Amplifier

29. The 741 Operational Amplifier

30. The 741 Operational Amplifier

31. The Ideal Operational Amplifier

32. The Ideal Operational Amplifier

33. Integrating Amplifier

34. Differentiating Amplifier

35. First-order Filters

36. First-order Low-pass Filter

37. First-order Low-pass Filter

38. First-order High-pass Filter

39. First-order High-pass Filter

40. First-order Band-pass Filter

41. First-order Bandstop Filter

42. Second (and higher) Order Filters

43. Second-order Lowpass Filter

44. Second-order Lowpass Filter

45. Second-order Highpass Filter

46. Second-order Highpass Filter

47. Second-order Band-pass Filter

48. Second-order Band-pass Filter

49. Other Op Amp Circuits

50. Frequency Dependence of Open-Loop Gain
sedr42021_0222.jpg

51. Slew Rate
sedr42021_0226a.jpg

52. Slew Rate
sedr42021_0227.jpg