Op Amp Fundamentals
([HUFLVH1RQLQYHUWLQJ$PSOL¿HU'&2SHUDWLRQ
(;(5&,6(2%-(&7,9(
using dc inputs. You will verify circuit operation with a multimeter.
',6&866,21
Student Manual
FACET by Lab-Volt
77
Op Amp Fundamentals
O
circuit common.
a. inverts the input voltage polarity.
b. does not invert the input voltage polarity.
Can the feedback resistor be adjusted to produce a circuit gain of 1?
a. Yes, if R3 is set for minimum resistance.
b. Yes, if R3 is set for about 4500 :.
c. No.
Student Manual
78
FACET by Lab-Volt
Op Amp Fundamentals
at
nearly 0 V.
In a noninverting op amp, the voltage at the inverting input is always held to 0 V.
a. true
b. false
Student Manual
FACET by Lab-Volt
79
Op Amp Fundamentals
I
When VI
Student Manual
80
FACET by Lab-Volt
Op Amp Fundamentals
352&('85(
฀
Locate the NON-INVERTING AMPLIFIER circuit block, and connect the circuit shown. Make
sure the circuit input is connected to circuit common.
฀
O
Monitor the circuit output as you remove the circuit input-to-common connection. For this
Based on your observation, the op amp is
a. saturated.
b. not saturated.
Student Manual
FACET by Lab-Volt
81
Op Amp Fundamentals
฀
procedure.
฀
I
Based on the circuit input and output voltages, what is the circuit gain?
Av =
฀
Recall Value 1
Based on your voltmeter indications, are the input and output voltage polarities identical?
a. yes
b. no
฀
Use your voltmeter to measure the differential input voltage [V
Your reading indicates that
a.
b.
c.
d.
U1 is saturated.
U1 is operating normally.
circuit current is 0.
the circuit now operates as an inverting
Student Manual
82
FACET by Lab-Volt
Op Amp Fundamentals
฀
You measured a circuit voltage gain of about
Recall Value 1
values given, which formula is correct?
a.
b.
c.
d.
฀
Measure the voltage at each input terminal of the op amp.
Based on your readings,
a.
b. V should be +2 Vdc.
c. a circuit summing junction does not exist.
d.
I
฀
฀
O
O
I
a. yes
b. no
Student Manual
FACET by Lab-Volt
83
Op Amp Fundamentals
฀
control from end to end.
Based on V ,
a.
b.
c.
d.
฀
U1 is not saturated.
the op amp compensates for the entire input voltage range.
U1 is saturated for the total input voltage range.
U1 is saturated for a partial range of input voltages.
I
Based on the voltage drops of R1, R2, and R4,
a.
b. the current through R2 essentially equals the current through R1.
c. the voltage across R2 is 9 times greater than the voltage across R1.
d. All of the above.
฀
Adjust VI to +1.0 Vdc. Be precise.
Based on the voltage drops of R1, R2, and R4,
a.
b. the current through R2 essentially equals the current through R1.
c. the voltage across R2 is 9 times greater than the voltage across R1.
d. All of the above.
Student Manual
84
FACET by Lab-Volt
Op Amp Fundamentals
฀
Place CM switch 15 in the ON position to modify the value of R2. Adjust VI to a convenient
฀
Based on the input and output voltages of your circuit, the gain
a. increased and R2 decreased.
b. decreased and R2 decreased.
฀
Based on your circuit observations, a change of VI causes a change in VO because
a.
b.
c.
d.
feedback voltage is required to maintain V at 0 V.
the input voltage change initially upsets the balanced op amp input differential voltage.
the op amp uses the change in VO
All of the above.
฀
&21&/86,21
•
A noninverting op amp circuit can be adjusted to minimize offset voltage errors.
•
In a noninverting op amp circuit, the input and output voltage polarities are identical.
•
•
•
•
Student Manual
FACET by Lab-Volt
85
Op Amp Fundamentals
5(9,(:48(67,216
1. Locate the NON-INVERTING AMPLIFIER circuit block and connect the circuit shown.
block to generate an input voltage for your op amp circuit.
What is the approximate circuit gain?
a.
b.
c.
d.
0.15
1.5
15
150
2. The TRIM adjust potentiometer in this circuit
a.
b.
c.
d.
minimizes offset errors.
adjusts circuit gain.
prevents op amp saturation.
controls the amount of feedback voltage.
3.
a. does not change the circuit input voltage polarity.
b.
c. Both of the above.
d. None of the above.
4. The noninverting terminal of this circuit serves as the
a.
b.
c.
d.
input reference of the circuit.
circuit input terminal.
summing junction.
All of the above.
5.
a.
b.
c.
d. Both inputs of U1 are at virtual ground.
127(
Student Manual
86
FACET by Lab-Volt