Electronics and Communication Engineering - Electronic Devices and Circuits

26. 

An amplifier with resistive -ve feedback has two left poles in its open loop transfer function. The amplifier

A. will always be unstable at high frequencies
B. will be stable for all frequencies
C. may be unstable, depending on the feedback factor
D. will oscillate at low frequencies

Answer: Option B

Explanation:

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27. 

Amplification of ultrasonic waves is possible in a piezoelectric semiconductor under applied electric field. The basic phenomenon involved is known as

A. electrostriction
B. acousto-optic interaction
C. acousto-electric interaction
D. stimulated Brillouin scattering

Answer: Option C

Explanation:

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28. 

For a junction FET in the pinch off region, as the drain voltage is increased, the drain current

A. becomes zero
B. abruptly decrease
C. abruptly increases
D. remains constant

Answer: Option D

Explanation:

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29. 

For a BJT, under the saturation region.

A. IC = βIB
B. IC > βIB
C. IC is independent of other parameter
D. IC < βIB

Answer: Option D

Explanation:

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30. 

In which mode of BJT operation are both junctions reverse biased?

A. Active
B. Saturation
C. Cut off
D. Reverse active

Answer: Option C

Explanation:

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