BJT Amplifiers and Oscillators MCQs

Question 1

While discussing amplifier performance, noise is defined as any kind of unwanted signal in the output which is

Accepted Answer

unrelated to the input signal

Answer

derived from the input signal not generated by the amplifier

Answer

due to associated circuitry

Question 2

An ideal amplifier has

Accepted Answer

noise factor of unity

Answer

noise figure of less than 1 dB

Answer

output SN more than input S/N

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noise figure of more than 0 dB

Question 3

Zero watt cannot be chosen as zero decibel level because

Accepted Answer

it would be impossible to define a decibel

Answer

it is impossible to measure zero watt

Answer

it is too small

Answer

every power compared with it would be zero

Question 4

A minus 3 dB point on the gain versus frequency curve of an amplifier is that point where

Accepted Answer

power falls to half its maximum value

Answer

signal frequency drops to half the mid-band frequency

Answer

voltage amplification becomes half of its maximum value

Answer

upper cut-off frequency becomes twice the lower cut-off frequency

Question 5

The bandwidth of an amplifier may be increased by

Accepted Answer

minimizing its stray capacitances

Answer

decreasing the capacitance of its by pass capacitors

Answer

increasing input signal frequency

Answer

cascading it

Question 6

Lower cut-off frequency of an amplifier is primarily determined by the

Accepted Answer

capacitances of coupling and bypass capacitors.

Answer

interval capacitances of the active device used

Answer

stray capacitance between its wiring and ground

Answer

ac 12. value of its active devices

Question 7

The gain-bandwidth product of an amplifier is given by

Accepted Answer

fT

Answer

f2 ?

Answer

f ?

Answer

I3f

Question 8

A circuit which resonates at 1 MHz has a of 100. Bandwidth between half-power points is

Accepted Answer

10 IcHz

Answer

100 kHz

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10 hz

Answer

100 Hz

Question 9

The decibel gain of a cascaded amplifier equals the

Accepted Answer

sum of individual gains

Answer

product of individual gains

Answer

ratio of stage gains

Answer

product of voltage and current gains