OBJECTIVES: to simulate a non-inverting operational amplifier circuit and measure its gain to simulate and measure an inverting summing op amp circuit


EQUIPMENT:
PRE-LAB: autorange digital multimeter (MS8217) resistors, set A: 2.2 k

, 6.8 k

, 100 k
 resistors, set B: 1 k

, 2.2 k

, 4.7 k

, 100 k

, 200 k
 operational amplifiers: AD 8541, ST UA741CN jumper wires: 6 (2 orange, 1 blue, 1 red, 1 white, 1 black) triple-output DC power supply -- Hewlett Packard E3631A function generator -- Keysight 33210A oscilloscope -- Keysight DSO-X 2022A
Complete the following 13 steps before arriving to perform Lab #4.
1.
In PSpice, build and simulate (using “Time Domain” analysis) the op-amp circuit in Figure 1.
Choose the values of R
1
, R
2
, and R
3
from resistor set A (in the Equipment list)
to provide a gain of approximately 4 from v in
to v out
.
Use the 741 op amp (“EVAL” library, “uA741” part). Apply +15 V to Pin 7 and –15 V to Pin 4.
For v in
, input a sine wave at 20 kHz with an amplitude of 2 V pp
(Volts, peak-to-peak).
(“SOURCE” library, “VSIN” part)
Figure 1. Non-inverting op-amp circuit.
2.
Plot v in
and v out
in the Trace window. Adjust your simulation time
(and/or the time scale on your trace window) to view two cycles of the sinusoids.
3.
Compute the voltage gain of the circuit as A v,20k
= { amplitude of v out
} / { amplitude of v in
} .
4.
Make a printout of your schematic and your simulation results,
and attach your printouts to your lab notebook.
5.
Change the frequency of v in
to 5 kHz, re-run the simulation, and re-compute the gain as A v,5k
.
6.
Change the frequency of v in
to 1 kHz, re-run the simulation, and re-compute the gain as A v,1k
.
7.
Increase the amplitude of v in
to 12 V pp
, re-run the simulation, and re-compute the gain as A
 v,1k
.
1

8.
In PSpice, build and simulate the op-amp circuit in Figure 2.
Choose the values of R
4
, R
5
, R
6
, R
7
, and R
8
from resistor set B to achieve v o
 
2 v
1

5 v
2
.
For v
1
, input a constant 650 mV .
For v
2
, input a triangle wave at 50 Hz with an amplitude of 400 mV pp
.
Use the “VPULSE” part (“SOURCE” library) to mimic a triangle wave by setting pulse width
(“PW”) to zero and setting rise time (“TR”), fall time (“TF”), and period (“PER”) appropriately.
Figure 2. Summing (and inverting) op-amp circuit.
9.
Plot v
1
, v
2
, and v o
in the Trace window. View two cycles of the triangle waves.
Write the maximum and minimum values of v
2
as V
2,max and V
2,min
.
Write the maximum and minimum values of v o
as V o,max and V o,min
.
10.
Make a printout of your schematic and your simulation results, and attach these to your notebook.
11.
Ensure that you have the following resistors: 1 k

, 2.2 k

, 4.7 k

, 6.8 k

, 100 k

, 200 k

.
Using your MS8217 as a DC ohmmeter, measure each resistor, record its true value, and compute percent error from nominal. Ensure that no percent error is greater than 10% before proceeding.
12.
Construct the circuit of Figure 1 from your first PSpice schematic.
Use the Analog Devices AD8541 op amp as a placeholder for the 741 op amp.
Add jumper wires for v in
(2 orange), v out
(1 blue), +15 V (1 red),
–15 V (1 white), and ground (1 black) .
13.
Print the pinout (“Pin Connections” or “Pin Configurations”) for a 741 operational amplifier
(e.g. from a UA741CN data sheet) and attach it to your lab notebook.
PROCEDURE:
Non-Inverting Op Amp Circuit & Introduction to the Function Generator and Oscilloscope
14.
Replace the AD8541 op amp with a 741 op-amp provided to you by your lab instructor.
15.
Using the

25-V/1-A supplies on the HP E3631A,
apply +15 V (Pin 7) and –15 V (Pin 4) to the 741 op amp.
16.
Turn on the Keysight 33210A function generator, set it to high-impedance mode,
(“Utility” button 
“Output Setup”

“High Z”

“DONE”), and turn the output on.
Using the 33210A for v in
, apply a sine wave at a frequency of 20 kHz and an amplitude of 2 V pp
.
17.
Attach Channel 1 of the Keysight DSO-X oscilloscope to v in
(using a probe, on the breadboard)
and verify 2 V pp
as measured by the oscilloscope.
Adjust the voltage scale (“Analog” panel, left-hand knob) and the
time scale (“Horizontal” panel, left-hand knob) to view between 1 and 10 sinusoidal cycles.
To measure peak-to-peak voltage on the oscilloscope automatically, use the Measurement menu:
“Meas” button

“Source: 1”

“Type: Peak-Peak”

“Add Measurement”
2

If necessary, adjust the amplitude of the sinusoid (slightly) to measure 2.0 V pp
on the oscilloscope.
If necessary, adjust the oscilloscope trigger to a level within your waveform
to provide a steady time reference ( t = 0) for each oscilloscope capture. (“Trigger” button

“Trigger Type: Edge”

“Source: 1”

adjust “Level” knob to fit inside waveform)
18.
Attach Channel 2 of the oscilloscope to v out
, adjust the voltage scale to view sinusoids,
and measure the peak-to-peak voltage of this waveform.
Record the peak-to-peak amplitude for v in
as V in,20k
. Record the amplitude for v out
as V out,20k
.
Calculate the voltage gain as A v,20k
= V out,20k
/ V in,20k
.
19.
Adjust the frequency of v in
to 5 kHz. Record V in,5k
, V out,5k
, and A v,5k
.
20.
Adjust the frequency of v in
to 1 kHz. Record V in,1k
, V out,1k
, and A v,1k
.
21.
Increase the amplitude of v in
from 2 V pp
to 12 V pp
. Note what happens to the output.
Record the new input, output, and gain as V
 in,1k
, V
 out,1k
, and A
 v,1k
.
Summing Op Amp Circuit & Introduction to Waveform Capture Software
22.
Construct the circuit of Figure 2 from your second PSpice schematic.
Use the 6-V/5-A supply on the E3631A as the 650-mV DC source.
Change the waveform to a triangular wave at 50 Hz with an amplitude of 400 mV
(“Ramp” button

“Symmetry” softkey

set to “50%”) pp
.
23.
Attach Channel 1 of the oscilloscope to v
2
and Channel 2 of the oscilloscope to v o
.
Adjust the voltage and time scales to view between 1 and 10 sinusoidal cycles.
24.
Measure the maximum and minimum values of v
2
and record them as V
2,max and V
2,min
.
(“Meas” button

“Source: 1”

“Type: Maximum”

“Add Measurement”)
(“Meas” button

“Source: 1”

“Type: Minimum”

“Add Measurement”)
25.
Measure the maximum and minimum values of v o
and record them as V o,max and V o,min
.
Ensure that the oscilloscope probes are set to DC coupling before you record V o,max
( number button for each channel

“Coupling” softkey

set to “DC” ) and V o,min
.
26.
Using the Keysight BenchVue software (separate hand-out), import the oscilloscope
traces for v
2
and v o
into an Excel worksheet so that you may reproduce the traces in your report.
27.
Complete the Data Analysis section before leaving the lab.
DATA ANALYSIS:
1.
Compute the percent error between the theoretical and measured values for A v
.
2.
Generate two plots: v
2
vs. time and v o
vs. time, using Excel.
QUESTIONS:
1.
Do your measured values for A v
match your theoretical values? Why or why not?
2.
Why is the circuit of Figure 1 a non-inverting amplifier ?
3.
Does the gain of the non-inverting amplifier depend on operating frequency? Why or why not?
4.
Does the gain of the non-inverting amplifier depend on input amplitude? Why or why not?
5.
Why is the circuit of Figure 2 a summing (inverting) amplifier ?
6.
How does your data demonstrate v o
 
2 v
1

5 v
2
?
3