BJT Amplifiers

mcqspedia.com has 76 Question/Answers about Topic BJT Amplifiers

For the common-emitter amplifier ac equivalent circuit, all capacitors are

For the common-emitter amplifier ac equivalent circuit, all capacitors are
  • A. effectively shorts.
  • B. effectively open circuits.
  • C. not connected to ground.
  • D. connected to ground.
  • Correct Answer: Option A

For a common-emitter amplifier, the purpose of the emitter bypass capacitor is

For a common-emitter amplifier, the purpose of the emitter bypass capacitor is
  • A. no purpose, since it is shorted out by RE.
  • B. to reduce noise.
  • C. to despike the supply voltage.
  • D. to maximize amplifier gain.
  • Correct Answer: Option D

For a common-emitter amplifier, the purpose of swamping is

For a common-emitter amplifier, the purpose of swamping is
  • A. to minimize gain.
  • B. to reduce the effects of r'e
  • C. to maximize gain.
  • D. no purpose.
  • Correct Answer: Option B

An emitter-follower is also known as a

An emitter-follower is also known as a
  • A. common-emitter amplifier.
  • B. common-base amplifier.
  • C. common-collector amplifier.
  • D. Darlington pair.
  • Correct Answer: Option C

In a common-base amplifier, the input signal is connected to the

In a common-base amplifier, the input signal is connected to the
  • A. base.
  • B. collector.
  • C. emitter.
  • D. output.
  • Correct Answer: Option C

The differential amplifier produces outputs that are

The differential amplifier produces outputs that are
  • A. common mode.
  • B. in-phase with the input voltages.
  • C. the sum of the two input voltages.
  • D. the difference of the two input voltages.
  • Correct Answer: Option D

The differential amplifier has

The differential amplifier has
  • A. one input and one output.
  • B. two inputs and two outputs.
  • C. two inputs and one output.
  • D. one input and two outputs.
  • Correct Answer: Option C

The dc emitter current of a transistor is 8 mA. What is the value of re?

The dc emitter current of a transistor is 8 mA. What is the value of re?
  • A. 320
  • B. 13.3 k
  • C. 3.125
  • D. 5.75
  • Correct Answer: Option C

An emitter-follower amplifier has an input impedance of 107 k. The input signal is 12 mV. The approximate output voltage is (common-collector)

An emitter-follower amplifier has an input impedance of 107 k. The input signal is 12 mV. The approximate output voltage is (common-collector)
  • A. 8.92 V
  • B. 112 mV
  • C. 12 mV
  • D. 8.9 mV
  • Correct Answer: Option C

A Darlington pair amplifier has

A Darlington pair amplifier has
  • A. high input impedance and high voltage gain.
  • B. low input impedance and low voltage gain.
  • C. a voltage gain of about 1 and a low input impedance.
  • D. a low voltage gain and a high input impedance.
  • Correct Answer: Option D

You have a need to apply an amplifier with a very high power gain. Which of the following would you choose?

You have a need to apply an amplifier with a very high power gain. Which of the following would you choose?
  • A. common-collector
  • B. common-base
  • C. common-emitter
  • D. emitter-follower
  • Correct Answer: Option C

A common-emitter amplifier has ________ voltage gain, ________ current gain, ________ power gain, and ________ input impedance.

A common-emitter amplifier has ________ voltage gain, ________ current gain, ________ power gain, and ________ input impedance.
  • A. high, low, high, low
  • B. high, high, high, low
  • C. high, high, high, high
  • D. low, low, low, high
  • Correct Answer: Option B

To analyze the common-emitter amplifier, what must be done to determine the dc equivalent circuit?

To analyze the common-emitter amplifier, what must be done to determine the dc equivalent circuit?
  • A. leave circuit unchanged
  • B. replace coupling and bypass capacitors with opens
  • C. replace coupling and bypass capacitors with shorts
  • D. replace VCC with ground
  • Correct Answer: Option B

What is re equal to in terms of h parameters?

What is re equal to in terms of h parameters?
  • A. hre / hoe
  • B. (hre + 1) / hoe
  • C. hie – (hre / hoe)(1 + hfe)
  • D. hfe
  • Correct Answer: Option A

The advantage that a Sziklai pair has over a Darlington pair is

The advantage that a Sziklai pair has over a Darlington pair is
  • A. higher current gain.
  • B. less input voltage is needed to turn it on.
  • C. higher input impedance.
  • D. higher voltage gain.
  • Correct Answer: Option B

Which of the following techniques can be used in the sinusoidal ac analysis of transistor networks?

Which of the following techniques can be used in the sinusoidal ac analysis of transistor networks?
  • A. Small-signal
  • B. Large-signal
  • C. Small- or large-signal
  • D. None of the above
  • Correct Answer: Option C

What is the limit of the efficiency defined by = Po / Pi?

What is the limit of the efficiency defined by = Po / Pi?
  • A. Greater than 1
  • B. Less than 1
  • C. Always 1
  • D. None of the above
  • Correct Answer: Option B

Which of the following define(s) the conversion efficiency?

Which of the following define(s) the conversion efficiency?
  • A. Ac power to the load/ac input power
  • B. Ac power to the load/dc power supplied
  • C. Dc output power/ac input power
  • D. All of the above
  • Correct Answer: Option B

Which of the following should be done to obtain the ac equivalent of a network?

Which of the following should be done to obtain the ac equivalent of a network?
  • A. Set all dc sources to zero
  • B. Replace all capacitors by a short-circuit equivalent.
  • C. Remove all elements bypassed by the short-circuit equivalent.
  • D. All of the above
  • Correct Answer: Option D

What is the range of the current gain for BJT transistor amplifiers?

What is the range of the current gain for BJT transistor amplifiers?
  • A. less than 1
  • B. 1 to 100
  • C. above 100
  • D. All of the above
  • Correct Answer: Option D
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