Operational Amplifier & Applications MCQ


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