Multiple Choice
Questions and
Answers on OpAmp ( Operational
Amplifier )
Q1. A differential amplifier
..
1.
is a part of an Op-amp
2.
has one input and one
output
3.
has two outputs
4.
answers (1) and (2)
Answer : 4
Q 2. When a differential
amplifier is operated singleended,
1.
the output is grounded
2.
one input is grounded and
signal is applied to the other
3.
both inputs are connected
together
4.
the output is not inverted
Answer : 2
Q3. In differential-mode,
.
1.
opposite polarity signals
are applied to the inputs
2.
the gain is one
3.
the outputs are of different
amplitudes
4.
only one supply voltage is
used
Answer : 1
Q4. In the common mode,
1.
both inputs are grounded
2.
the outputs are connected
together
3.
an identical signal appears
on both the inputs
4.
the output signal are inphase
Answer : 3
Q5. The common-mode gain
is ..
1.
very high
2.
very low
3.
always unity
4.
unpredictable
Answer : 2
Q6. The differential gain is
1.
very high
2.
very low
3.
dependent on input
voltage
4.
about 100
Answer : 1
Q7. If ADM = 3500 and ACM =
1.
700 nA
0.35, the CMRR is .
2.
99.3 A
1.
1225
3.
49.7 A
2.
10,000
4.
none of these
3.
80 dB
Answer : 1
4.
answers (1) and (3)
Q11. The output of a
Answer : 4
particular Op-amp increases
Q8. With zero volts on both
8V in 12s. The slew rate is
inputs, an OP-amp ideally
should have an output
1.
90 V/s
..
2.
0.67 V/s
3.
1.5 V/s
4.
none of these
1.
equal to the positive
supply voltage
2.
equal to the negative
supply voltage
Answer : 2
Q12. For an Op-amp with
3.
equal to zero
negative feedback, the
4.
equal to CMRR
output is .
Answer : 3
1.
equal to the input
Q9. Of the values listed, the
2.
increased
most realistic value for
3.
fed back to the inverting
open-loop voltage gain of an
OP-amp is
input
4.
fed back to the
1.
2.
2000
Answer : 3
3.
80 dB
Q13. The use of negative
4.
100,000
feedback
Answer : 4
noninverting input
1.
Q10. A certain OP-amp has
bias currents of 50 A. The
input offset current is ..
reduces the voltage gain of
an Op-amp
2.
makes the Op-amp
oscillate
3.
makes linear operation
possible
4.
answers (1) and (2)
4.
depends on Ri
Answer : 1
Q17. A certain inverting
Answer : 4
amplifier has a closed-loop
Q14. Negative feedback
voltage gain of 25. The Op-
..
amp has an open-loop
1.
increases the input and
output impedances
2.
increases the input
impedance and bandwidth
3.
decreases the output
impedance and bandwidth
4.
does not affect impedance
voltage gain of 100,000. If
an Op-amp with an openloop voltage gain of 200,000
is substituted in the
arrangement, the closedloop gain ..
1.
doubles
2.
drops to 12.5
Answer : 2
3.
remains at 25
Q15. A certain noninverting
4.
increases slightly
or bandwidth
amplifier has Ri of 1 k and
Answer : 3
Rf of 100 k. The closed-loop
Q18. A voltage follower
voltage gain is
1.
100,000
1.
has a voltage gain of 1
2.
1000
2.
is noninverting
3.
101
3.
has no feedback resistor
4.
100
4.
has all of these
Answer : 3
Answer : 4
Q16. If the feedback resistor
Q19. The Op-amp can
in Q15 (above question) is
amplify
open, the voltage gain .
1.
a.c. signals only
1.
increases
2.
d.c. signals only
2.
decreases
3.
both a.c. and d.c. signals
3.
is not affected
4.
neither d.c. nor a.c. signals
Answer : 3
Answer : 2
Q20. The input offset current
Q23. The tail current in a
equals the .
differential amplifier equals
1.
difference between two
base currents
2.
2.
3.
1.
half of either collector
current
2.
equal to either collector
current
3.
two times either collector
current
4.
equal to the difference in
base currents
collector current divided by
current gain
4.
Q21. The tail current of a
differential amplifier is .
sum of two emitter
currents
none of these
Answer : 1
difference between two
emitter currents
collector current divided by
current gain
4.
1.
average of two base
currents
3.
collector voltage divided
by collector resistance
Answer : 2
Q24. The differential voltage
gain of a differential
amplifier is equal to RC
divided by .
1.
re
2.
re/2
3.
2re
4.
RE
Answer : 3
Answer : 3
Q22. The node voltage at the
Q25. The input impedance of
top of the til resistor is
a differential amplifier
closes to .
equals re times
1.
collector supply voltage
1.
2.
zero
2.
RE
3.
emitter supply voltage
3.
RC
4.
tail current times base
4.
resistance
Answer : 4
Q26. A common-mode signal
2.
class B push-pull amplifier
is applied to .
3.
CE amplifier
4.
swamped amplifier
1.
the noninverting input
2.
the inverting input
Answer : 1
3.
both iputs
Q29. The common-mode
4.
top of the tail resistor
voltage gain of a differential
Answer : 3
amplifier is equal to
Q27. The common-mode
RC divided by ..
voltage gain is
1.
smaller than differentail
voltage gain
2.
equal to differential
voltage gain
3.
greater than differential
voltage gain
4.
re
2.
2re
3.
re/2
4.
2RE
Answer : 4
Q30. Current cannot flow to
ground through .
1.
a mechanical ground
Answer : 1
2.
an a.c. ground
Q28. The input stage of an
3.
a virtual ground
Op-amp is usually a .
4.
an ordinary ground
1.
none of the above
1.
differential amplifier
Answer : 3
