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Feedback Amplifiers MCQs

Practice Feedback Amplifiers MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1
Electronic Devices & CircuitsFeedback Amplifiers

Negative feedback in an amplifier generally tends to?

  • AIncrease gain sensitivity to device variations
  • BReduce bandwidth
  • CImprove gain stability and increase bandwidth
  • DForce the amplifier into saturation
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Correct Answer: C. Improve gain stability and increase bandwidth
Explanation: Negative feedback normally reduces closed-loop gain but improves stability, linearity and bandwidth.
Reference: Standard analog electronics: negative feedback
Question 3
Analog ElectronicsFeedback Amplifiers

Negative feedback generally makes an amplifier’s closed-loop gain?

  • AMore stable against parameter variations
  • BInfinitely large
  • CMore sensitive to transistor beta
  • DAlways zero
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Correct Answer: A. More stable against parameter variations
Explanation: Negative feedback sacrifices some gain but improves gain stability against device and circuit variations.
Reference: Standard analog electronics: feedback amplifiers
Question 4
Analog ElectronicsFeedback Amplifiers

Negative feedback generally has what effect on amplifier bandwidth?

  • AUsually decreases it to zero
  • BUsually increases it
  • CNever affects it
  • DMakes frequency negative
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Correct Answer: B. Usually increases it
Explanation: A common benefit of negative feedback is wider useful bandwidth while closed-loop gain is reduced.
Reference: Standard analog electronics: feedback amplifiers
Question 6
Analog ElectronicsFeedback Amplifiers

An unbypassed emitter resistor in a common-emitter amplifier primarily introduces?

  • APositive feedback
  • BEmitter degeneration or negative feedback
  • COscillation at all frequencies
  • DAvalanche breakdown
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Correct Answer: B. Emitter degeneration or negative feedback
Explanation: The emitter resistor develops degenerative negative feedback, improving stability and linearity while reducing gain.
Reference: Standard analog electronics: feedback amplifiers
Question 8
Analog ElectronicsFeedback Amplifiers

In voltage-series negative feedback, the output resistance generally?

  • AIncreases
  • BDecreases
  • CBecomes infinite
  • DAlways equals input resistance
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Correct Answer: B. Decreases
Explanation: Voltage sampling with negative feedback generally lowers the closed-loop output resistance.
Reference: Standard analog electronics: feedback amplifiers
Question 10
Analog ElectronicsFeedback Amplifiers

An amplifier has A beta = 99. By what factor is its gain sensitivity to amplifier-parameter changes reduced compared with no feedback?

  • AApproximately 10
  • BApproximately 50
  • CApproximately 100
  • DApproximately 9900
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Correct Answer: C. Approximately 100
Explanation: The desensitivity factor is 1 + A beta = 100, so fractional gain variation is reduced by approximately a factor of 100.
Reference: Standard analog electronics: feedback amplifiers
Question 13
Analog ElectronicsFeedback Amplifiers

Which feedback topology is commonly used to obtain a voltage amplifier with increased input resistance and reduced output resistance?

  • AVoltage-series feedback
  • BVoltage-shunt feedback
  • CCurrent-series feedback only for current output
  • DCurrent-shunt feedback
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Correct Answer: A. Voltage-series feedback
Explanation: Series mixing raises input resistance and voltage sampling lowers output resistance, which is desirable for a voltage amplifier.
Reference: Standard analog electronics: feedback amplifiers
Question 14
Electronic Devices & CircuitsFeedback Amplifiers

For a voltage-series negative-feedback amplifier, applying negative feedback generally causes input resistance to?

  • AIncrease
  • BDecrease to zero
  • CRemain exactly unchanged in all cases
  • DBecome negative
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Correct Answer: A. Increase
Explanation: Series mixing at the input tends to increase the input resistance of a voltage-series feedback amplifier.
Reference: Standard analog electronics: feedback and input resistance
Question 15
Electronic Devices & CircuitsFeedback Amplifiers

For a voltage-series negative-feedback amplifier, output resistance generally?

  • ADecreases
  • BIncreases without limit
  • CBecomes exactly equal to input resistance
  • DIs independent of feedback in every circuit
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Correct Answer: A. Decreases
Explanation: Voltage sampling with negative feedback tends to reduce output resistance, improving voltage-source behavior.
Reference: Standard analog electronics: feedback and output resistance
Question 17
Electronic Devices & CircuitsFeedback Amplifiers

The sensitivity of closed-loop gain to variations in open-loop gain is reduced by approximately which factor in a negative-feedback amplifier?

  • A1+A beta
  • BA-beta
  • C1-A beta
  • DA/beta only
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Correct Answer: A. 1+A beta
Explanation: Negative feedback desensitizes the gain; fractional gain variation is reduced approximately by the desensitivity factor 1+Aβ.
Reference: Standard analog electronics: feedback desensitivity
Question 20
Analog ElectronicsFeedback Amplifiers

If negative feedback reduces an amplifier’s gain by a factor of 10 while approximately preserving gain-bandwidth product, its bandwidth ideally changes by roughly what factor?

  • ADecreases by 10
  • BIncreases by 10
  • CDoes not change
  • DIncreases by 100
Report an error
Correct Answer: B. Increases by 10
Explanation: Negative feedback commonly trades gain for bandwidth; under the constant gain-bandwidth approximation, a tenfold gain reduction gives about tenfold bandwidth increase.
Reference: Standard analog electronics: feedback bandwidth