To build a number of simple circuits containing
operational amplifiers (op-amps) and characterize their performance
as a function of frequency and input pulse shape.
Pre-lab preparation:
Assume the following components are available to design your lab:
Resistors: 0.47 k 1.0 k 2.0 k 3.3 k
4.7 k 10.0 k 20.0 k 47.0 k
Capacitors: 680 pF 0.01 µF 0.1 µF
4.7 µF 22 µF
Integrated circuits: LM74174163
Read Section 8.4 in Mayergoyz and Lawson.
Design the following circuits and draw the wiring diagrams. Assume you only have the
values listed above to construct the circuits. The only voltage supplies available are
+/- 12 V and +5 V.
An inverting amplifier op-amp circuit with a gain of about -10.
A non-inverting amplifier op-amp circuit with a gain of about 3.
A differentiator circuit with a "gain" at 3 kHz of about 0.2.
An integrator circuit with a "gain" at 3 kHz of about 5.
A circuit that has four inputs, v1 - v4, and whose output is: vo=(((v4/2+v3)/2+v2)/2+v1)/2.
Use PSpice to simulate the circuit in (2). Drive the op-amp with a
sinusoidal voltage source (vsin or vsrc). Start with a peak-to-peak amplitude
of Vpp=0.1 V and a frequency of 1 kHz. Vary the voltage amplitude from Vpp=0.1
to Vpp=10 V and plot the gain (Vout/Vpp) as a function of Vpp.
(The x axis should be a voltage which ranges from 0.1 to 10 V.) This plot may be
done by hand or with a spreadsheet program if you like. It can be done in PSpice,
but it isn't easy. Then, with the input voltage set to 2 V (peak-peak), vary the
input frequency from 1 kHz to 1 MHz and plot the gain versus frequency (This can
be easily done in PSpice).
Extra credit (5%): Use PSpice to simulate the circuit in (5). Drive
the inputs with a divide-by-16 counter. Use a 10 kHz clock and plot the output
as a function of time. Repeat the plot with a 300 kHz clock.
Extra credit (5%): Design a circuit whose output is: vo=(((v4/2-v3)/2+v2)/2-v1)/2.
Experiment:
During this experiment, be certain that you:
Ask the TA questions regarding any procedures about which you are uncertain.
Turn off all power supplies any time that you make any change to the
circuit.
Arrange your circuit components neatly and in a logical order.
Compare your breadboards carefully with your circuit diagrams before
applying power to the circuit.
BE CERTAIN YOU CAN ANSWER ALL THE POST-LAB QUESTIONS!!!
Complete the following tasks:
Construct the inverting amplifier op-amp circuit. Set the input voltage to
2 V (pp) and the frequency to 1 kHz and plot the output and input as a function
of time. Vary the input voltage from 0.1 V to 3 V and record the gain. Set the
input voltage to 2 V (pp) and record the gain for frequencies between 1 kHz and
1 MHz. (Take at least 4 points per decade).
Construct the non-inverting amplifier op-amp circuit. Use a triangular
input signal with a 2 V amplitude (pp) and plot the output and input time
dependence for a 1 kHz signal. Record the gain from 1 kHz to 1 MHz.
Construct the differentiator circuit. Plot the output and input signals
when the input signal is 2 V (pp) and the frequency is 3 kHz and the shape is
(a) a sine wave and (b) a square wave.
Construct the integrator circuit. Use a square wave input signal with a
peak-peak voltage of 2 V and a frequency of 3 kHz. Plot the output and input
signals.
Construct the voltage adder circuit (part 5). Use a the four outputs of
a divide-by-16 counter as the inputs to the voltage adder. Plot the output
voltage and the clock voltage as a function of time when the clock (sync out
on the function generator) is set to 10 kHz. Repeat for a clock frequency of
300 kHz.
(Extra credit 5%): Build the extra credit circuit and repeat
the previous test at 10 kHz.
Post-lab analysis:
Generate a lab report following the sample report available on the Web page.
Mention any difficulties encountered during the lab. Describe any results that
were unexpected and try to account for the origin of these results (i.e.
explain what happened).
IN ADDITION, answer the following questions:
Was there any degradation in the output pulse shape for any of the op-amp
circuits in any frequency range or voltage range? If so, when and why?
How did the experimental results compare with the computer simulations for
the non-inverting amplifier circuit?
Was the output from the differentiator as expected for both input sources?
Explain.
Was the output from the integrator as expected for both input sources?
Explain.
Was the output from the voltage adder as expected at both frequencies? If
not, why not?
The voltage adder circuit functions as a D/A converter. What advantages
does it have over the passive D/A converter that we built in Lab #8? What
disadvantages?