Operational Amplifiers (Op-amp) MCQ
Operational Amplifiers (Op-amp) MCQ, Op-amp MCQ, Multiple Choice Questions on Op-amp, Objective Questions on Operational Amplifiers (Op-amp), Operational Amplifiers (Op-amp) questions with answers, GATE questions on Operational Amplifiers (Op-amp), Engineering MCQ, Electronics Device MCQ
Multiple Choice Questions
Q.1. A differential amplifier ………..
- is a part of an OP-amp
- has one input and one output
- both
- none of the above
Answer: both
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: one input is grounded and signal is applied to the other
Q.3. 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: opposite polarity signals are applied to the inputs
Q.4. In the common-mode, …………..
- both inputs are grounded
- the outputs are connected together
- an identical signal appears on both inputs
- the output signals are in-phase
Answer: an identical signal appears on both inputs
Q.5. The common-mode gain is ….
- very high
- very low
- always unity
- unpredictable
Answer: very low
Q.6. The differential gain is ….
- very high
- very low
- dependent on input voltage
- about 100
Answer: very high
Q.7. If ADM = 3500 and ACM = 0.35, the CMRR is ….
- 1225
- 10,000
- 80 dB
- 10,000 & 80 dB
Answer: 10,000 & 80 dB
Q.8. 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 the CMRR
Answer: equal to zero
Q.9. 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: 100,000
Q.10. A certain OP-amp has bias currents of 50 μA and 49.3 μA. The input offset current is ….
- 700 nA
- 99.3 μA
- 49.7 μA
- none of these
Answer: 700 nA
Q. 11. The output of a particular OP-amp increases 8 V in 12 μs. The slew rate is ….
- 90 V/μs
- 0.67 V/μs
- 1.5 V/μs
- none of these
Answer: 0.67 V/μs
Q.12. For an OP-amp with negative feedback, the output is ….
- equal to the input
- increased
- feed back to the inverting input
- feed back to the noninverting input
Answer: feed back to the inverting input
Q.13. The use of negative feedback ….
- reduces the voltage gain of an OP-amp
- makes linear operation possible
- both
- none of the above
Answer: both
Q.14. 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: increases the input impedance and bandwidth
Q.15. 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: 101
Q.16. If feedback resistor in Q.15 is open, the voltage gain ……………
- increases
- decreases
- is not affected
- depends on Ri
Answer: increases
Q.17. 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: remains at 25
Q.18. A voltage follower ….
- has a voltage gain of 1
- in noninverting
- has no feedback resistor
- has all of these
Answer: has all of these
Q.19. 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: both a.c. and d.c. signals
Q.20. 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: difference between two base currents
Q.21. 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: two times either collector current
Q.22. The node voltage at the top of the tail resistor is closest to ….
- collector supply voltage
- zero
- emitter supply voltage
- tail current times base resistance
Answer: zero
Q.23. 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: sum of two emitter currents
Q.24. The differential voltage gain of a differential amplifier is equal to RC divided by ….
- r′e
- r′e/2
- 2 r′e
- RE
Answer: 2 r′e
Q.25. The input impedance of a differential amplifier equals r′e times ….
- β
- RE
- RC
- 2β
Answer: 2β
Q.26. A common-mode signal is applied to ….
- the noninverting input
- the inverting input
- both inputs
- top of the tail resistor
Answer: both inputs
Q.27. The common-mode voltage gain is ….
- smaller than differential voltage gain
- equal to differential voltage gain
- greater than differential voltage gain
- none of the above
Answer: smaller than differential voltage gain
Q.28. The input stage of an OP-amp is usually a ….
- differential amplifier
- class B push-pull amplifier
- CE amplifier
- swamped amplifier
Answer: differential amplifier
Q,29. The common-mode voltage gain of a differential amplifier is equal to RC divided by ….
- r′e
- 2 r′e
- r′e /2
- 2 RE
Answer: 2 RE
Q.30. Current cannot flow to ground through ….
- a mechanical ground
- an a.c. ground
- a virtual ground
- an ordinary ground
Answer: a virtual ground