Operational Amplifiers (Op-amp) MCQ

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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

Answer:

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

Semiconductor Diode MCQ

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