Download Experiment # 07

Experiment # 07
Operational Amplifier Circuit I
Software Simulations
Object:
The objectives of these experiments are to illustrate the use of computer software to do simulations of
electrical circuits. In order to have a possibility, of comparison with real measurements we will do computer
simulations on the circuits that we have already measured in the previous experiment and compare,
Apparatus:
 Pspice or Workbench software
 Personal computer
Software simulations:
We are interested in using the operational amplifier (op amp) A741. It is commercially available in the
following form:
Offset N1
IN IN+
V-
1
2
3
4
NC
V+
Vout
Offset
8
7
6
5
Fig. 1
In all the following we will use V+=+15V and V-= -15V.
1. Basic Op. Amp circuit adder
The following circuit gives the addition of two voltages V1 and V2:
R0
R1
V-
V1
Vout
V2
R2
V+ Fig.2
Where: Vout = - (
Ro
R1 V1 +
Ro
R2 V2 )
EGR 2402 Laboratory Manual
(1)
33
a) General characteristics:
1. Set-up this circuit (Fig. 2) using resistors in the range10 to100 KOhm. Print out a copy of it
2. Use a sinusoidal source for V1 with low frequency (f= 200 Hz and small amplitude (V = l V)
3. Set V2= 0 and select the resistors R0 and R1 so that Vout = -3V
4. Record these values of R0 and R1
5. Determine the value of Vout where saturation occurs
6. Vary the input frequency and simultaneously measure Vout and Vin
7. Determine the amplification A given by :
Vout
Vin
A=
8. Record your values in Table I :
f (KHz)
Vin
Vout
A
0.2
0.5
1
10
20
50
100
500
9. Plot A as a function of log (f) and discuss the result
b) Addition operation:
Set R1 = R2 and Equation (1) becomes
Vout =
Ro
( V1 + V2)
R1
(2)
2. Use a Sinusoidal input for V1
3. Use a DC input for V2
4. Measure Vout for different values of V1 and V2 and record your results in Table II:
V1 (VAC)
V2 (VDC)
V1 + V2
2
1
4
1.5
6
3
8
4
10
6
Vout
5. Plot Vout versus (V1 + V2) and determine the addition gain (or slope) Aad
6. Compare Aad to the value obtained from Equation (2) and give the % error
II. Basic circuit for difference
The following circuit can be used to differentiate two input voltages V1and V2:
EGR 2402 Laboratory Manual
34
R0
V-
R1
V1
Vout
V2
R2
V+
Ro
Fig.3
The output voltage is given by:
R0
R1 ( (V2 – V1 )
Vout =
(3)
1.Set up the circuit in Fig. 3 for simulation and print out a copy of it
2.Use a sinusoidal input for V1 and a DC input for V2
3.Measure Vout for different values of V1 and V2 and record your results in Tahle III
V1 (VAC)
V2 –V1
V2 (VDC)
2
1
4
1.5
6
3
8
4
10
6
Vout
4. Plot Vout versus (V2 – V1 ), and determine the differential gain (or slope) Ad
5. Compare Ad to the value obtained from Equation (3) and give the % error.
6. What can you say about the simulation?
III. Basic circuit for integration:
The following circuit is used to perform the integral of an input function
Ro
C
V-
R1
Vin
Vout
V+
Fig.4
The output voltage is given by :
Vout =
1
f  Vin dt
RC
(4)
a) Square wave input:
EGR 2402 Laboratory Manual
35
1. Set up the circuit in Fig. 4 and use Vin as a square wave (2V amplitude)
2. Print out a copy of this circuit with all the necessary parts
3. Choose R, R0, and C so that Vout corresponds to the integral form of Vin
4. Record these value of R, Ro, and C
5. Observe Vin and Vout simultaneously on the screen and print out a copy
6. Compare Vout to Vin and explain what you observed
7. Compare your results with the experimental values
b) Sinusoidal input:
1. Use a sine wave as input (2V amplitude)
2. What is the form of Vout?
3. Print out a plot of Vin and Vout on the same graph
4. Change the frequency f of Vin and observe Vout
5. Does the frequency of Vout changes?
6. How does the amplitude of Vout changes with respect to f?
7. Compare to your experimental results
IV. Basic circuit for differentiation
The following circuit is normally used to differentiate an input function
R
V-
R1
Vin
Vout
fig.5
The output signal is given by :
Vout = - RC
dVin
dt
(5)
a) Triangular wave input:
1. Set up the circuit in Fig. 5 and print out a copy of it
2. Use a triangular wave for Vin with amplitude of 2V
3. Choose R so that Vout corresponds to the derivative forrn of Vin and record this value of R and C
4. Print a plot of the observed forms of Vin and Vout on the same graph
5. Compare to your experimental results
b) Sinusoidal input:
1. Use a sine wave as input (2V amplitude)
2. What is the form of Vout
3. Print out a plot of Vin and Vout on the same graph
4. Change the frequency of Vin and observe Vout
5. Does the amplitude of Vout changes with f ?
6. Compare to your experimental results
Conclusions:
1. Summarize briefly what you have learned in these simulations
EGR 2402 Laboratory Manual
36
Experiment # 07
Name:
Section:
Operational Amplifier Circuit I:
Software Simulations
I. Basic Op.Amp. Circuit adder:
a) General characteristics:
4. The values of R0 and R1
5. The value of Vout where saturation occurs
f(KHz)
Vin
Vout
A
V2 (VDC)
V1 + V2
Vout
V1 - V2
Vout
0.2
0.5
10.0
20.0
50.0
100.0
500.0
b) Addition operation :
V1 (VAC)
2
1
4
1.5
6
3
8
4
10
6
II Basic circuit for difference
V1 (VAC)
V2 (VDC)
2
1
4
1.5
6
3
8
4
10
6
a) Square wave input:
4. The values of R, R0 and C
EGR 2402 Laboratory Manual
37
5. Plot the observation forms of Vin and Vout (on the same graph)
b) Sinusoidal input:
3. Plot the observed forms of Vin and Vout (on the same graph) :
IV. Basic circuit for differentiation
a) Triangular wave input:
3. The values of R and C
4. Plot the observed forms of Vin and Vout (on the same graph):
b) Sinusoidal input:
3. Plot the observed forms of Vin and Vout (on the same graph)
EGR 2402 Laboratory Manual
38