1. Chapter 8 The Operational Amplifier (Part I) ~ Using PSpice
The Ideal Op Amp
Noninverting Ideal Op Amp
Op Amp Giving Voltage Difference Output
Frequency Response of the Op Amp
Using a Subcricuit for the Op Amp
Op Amp differentiator Circuit
Op Amp Integrator Circuit
Response to Unit Step Function
Double Op Amp Circuit

2. The Ideal Op Amp
High input resistance, zero output resistance, and high voltage gain

3. The Ideal Inverting Op Amp
Negative feedback connection
PSpice version of the circuit

4. Input File Ideal Operational Amplifier VS 1 0 1V E 3 0 0 2 200E3
RI 2 0 1G
R K
R K
.OP
.OPT nopage
.TF V(3) VS
.END

5. Run the Analysis and Verify
Run  V(3)/VS=-9.999
Verify Vo/Vs=-R2/R1=-10K/1K=-10

6. Noninverting Ideal Op Amp
Noninverting ideal op amp model

7. Input File Ideal Operational Amplifier, Noninverting VS 1 0 1V
E E3
RI 1 2 1G
R k
R k
.op
.opt nopage
.TF V(3) VS
.END

8. Run and Verify
V(3)/VS=10,
Vo/Vs=1+R2/R1=1+9K/1K=10

9. Op Amp Giving Voltage Difference Output

10. Input File Op Amp Giving Voltage Difference Output VA 1 0 3V
VB V
E E3
RI 2 3 1G
R k
R k
R k
R k
.OP
.OPT nopage
.TF V(5) VB
.END

11. Run and Verify
Verify that Vo=R2(Vb-Va)/R1=10k(10v-3v)/5k=14v
V(5)=14V

12. Frequency Response of the Op Amp
Model for the frequency response of an op amp
fc=10Hz

13. Input File
Op Amp Model with 3-dB frequency at 10 Hz for Open-Loop Gain
VS 2 0 AC 1mV
EG E5 E
RI k RO
R k
RL k
RIN 1 2 1MEG
C uF
.AC DEC MEG
.PROBE
.END

14. Run and View Output

15. Modify Input File
Op Amp Model with 3-dB frequency at 10 Hz for Open-Loop Gain
VS 2 0 AC 1mV
EG E5 E
RI k RO
R k
R k
RL k
RIN 1 2 1MEG
C uF
.AC DEC MEG
.PROBE
.END

16. Parameter Setting

17. Run and View Output

18. Using a Subcircuit for the Op Amp
.subckt opamp m p vo
eg a 0 p m 1e5
e c 0 b 0 1
rin m p 1meg
ril a b 1k
c b uF
rol c vo 50
.ends

19. Op Amp Analysis Using Subcircuit
VS 2 0 AC 1mV
R k
R k
X opamp
.AC DEC MEG
.PROBE
.subckt opamp m p vo
eg a 0 p m 1e5
e c 0 b 0 1
rin m p 1meg
ril a b 1k
c b uF
rol c vo 50
.ends
.END

20. Op Amp Differentiator Circuit
Vo=-dv/dt

21. Input File Differentiator Circuit V 1 0 PWL (0, 0 1s, 1V 2s, 0)
C 1 2 2F R
X iop
.subckt iop m p vo
ri m p 1meg
e vo 0 p m 2e5
.ends
.TRAN 0.05s 2s
.PROBE
.END

22. Run and View Outputs
V(1) Vo

23. Op Amp Integrator Circuit

24. Input File Integrator Circuit
V 1 0 PWL ( ms, -1V 1s, -1V ms, 0V 2s, 0V
ms, 1V 3s, 1V) R
C 2 3 2
X iop
.subckt iop m p vo
ri m p 1meg
e vo 0 p m 2e5
.ends
.TRAN 0.05s 3s
.PROBE
.END

25. Run and View Output
V(1) Vo

26. Response to Unit Step Function
By definition, it remains at zero volts until t=0, and from that time forward it is 1V.

27. Response of first-order circuit to unit step function

28. Input File Vo(t)=(3-2e-4t)u(t) Response to Unit Step Function
Vs 1 0 PWL (0, 0 1us, 1v 5s, 1v) C
R 2 3 2 R
X iop
.subckt iop m p vo
ri m p 1meg
e vo 0 p m 2e5
.ends
.TRAN 0.05s 3s
.PROBE
.END
Vo(t)=(3-2e-4t)u(t)

29. Run and View Outputs

30. Double Op Amp Circuit

31. Input File Double Op Amp Circuit for Gain-Bandwidth Analysis
VS1 2 0 AC 1mV
R k
R k
X opamp
VS2 5 0 AC 1mV
R k
R k
X OPAMP
.AC DEC MEG
.PROBE
.subckt opamp m p vo
eg a 0 p m 1e5
e c 0 b 0 1
rin m p 1meg
ril a b 1k
c b uF
rol c vo 50
.ends
.END

32. Run and View Outputs
OP Amp 1
OP Amp 2

33. Chapter 8 The Operational Amplifier (Part II) ~ Using Capture
Noninverting Ideal Op Amp
Op Amp for Voltage-Difference Output
Frequency Response of the Op Amp
Frequency Response of the uA741
The uA741 as a Level Detector

34. Noninverting Ideal Op Amp
Ideal op amp in Capture
Ideal op amp

35. Run and View Output

36. Op Amp for Voltage-Difference Output

37. Run and View Output

38. Frequency Response of the Op Amp

39. Op amp model for fc=10Hz

40. Simulation Setting

41. Run and View Output
20*log10(V(5)/V(2))

42. DB(V(5)/V(2))

43. Frequency Response of the uA741

44. Run and View Output
Frequency response of the uA741

45. The uA741 as a Level Detector

46. V1 (VPWL) Settings
(0v, 0s), (3v, 0.2s), (5v, 0.4s), (-5v, 0.6s), (-3v, 0.8v), (0v, 1s)

47. Simulation Settings

48. Run and View Output
V(1) input
V(5) Output

49. Question & Answer