Multiple Choice Questions and Answers on Op-Amp ( Operational Amplifier )
Multiple Choice Questions and Answers on Op-Amp ( Operational Amplifier )
In addition to reading the questions and answers on my site, I would suggest you to check the following, on amazon, as well:
- Question Bank in Electronics & Communication Engineering by Prem R Chadha
- A Handbook on Electronics Engineering – Illustrated Formulae & Key Theory Concepts
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
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