Electronic Devices - BJT Amplifiers

Exercise :: BJT Amplifiers - General Questions

56. 

Which of the following configurations has a voltage gain of –RC /re?

A. Fixed-bias common-emitter
B. Common-emitter voltage-divider with bypass capacitor
C. Fixed-bias common-emitter and voltage-divider with bypass capacitor
D. Common-emitter voltage-divider without bypass capacitor

Answer: Option C

Explanation:

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57. 

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

Answer: Option C

Explanation:

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58. 

Which of the following is (are) true regarding the output impedance for frequencies in the midrange 100 kHz of a BJT transistor amplifier?

A. The output impedance is purely resistive.
B. It varies from a few ohms to more than 2 M.
C. An ohmmeter cannot be used to measure the small-signal ac output impedance.
D. All of the above

Answer: Option D

Explanation:

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59. 

Refer to this figure. The output signal from the first stage of this amplifier is 0 V. The trouble could be caused by

A. an open C4.
B. an open C2.
C. an open base-emitter of Q1.
D. a shorted C4.

Answer: Option C

Explanation:

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60. 

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

Answer: Option B

Explanation:

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