BJT Amplifiers and Oscillators MCQs

Question 1

"Power gain of a CB configuration is almost equal to its voltage gain." It is true?

Accepted Answer

Yes

Answer

No

Answer

Neither of the two

Answer

both (a) & (b)

Question 2

"Power gain of an amplifier in emitter?follower configuration is almost equal to its current gain." Comment !

Accepted Answer

It is a valid statement

Answer

It may be true under some circumstances

Answer

How can power gain equal voltage gain or current gain? It can never

Answer

none of these

Question 3

A source of 500 k.0 output impedance was to be connected to a load of 100. The matching device or circuit could be of two types. One was by using a CC (common collector) stage in-between and other to have a passive circuit having input and output impedances of 500 kfl and 10 0 respectively. Finally, CC stage was preferred even though it demanded much more component count and circuit complexity. Why?

Accepted Answer

It dose not alter circuit conditions because of its voltage gain being unite

Answer

Because, it dose not introduse any noise

Answer

Because, its impedances are extremely stable and do not vary with various parameters

Answer

none of these

Question 4

The reason for an amplifier in CC configuration having a very high input impedance is that

Accepted Answer

input is applied between base and the common terminal which is collector and that collector-base junction is always reverse-biased for transistor operation

Answer

it draws a very small amount of current when fed from a certain source

Answer

it is always fed from a very high impedance source whenever in operation

Answer

it has a very small resistance gain Ro Ri

Question 5

Reason for (CB) configuration having very small input impedance is

Accepted Answer

that input is applied between emitter and base and emitter junction is always forward biased for operation

Answer

because of its inherent characteristics

Answer

that it has a very large resistance gain RO

Answer

that it is always fed from a low impedance source

Question 6

Reason for (CB) configuration having a very high output impedance is

Accepted Answer

that output is taken across collector and base and collector ju,...tion has to be reversed biased for transistor operation

Answer

its inherent characteristic

Answer

because it always feeds a very high impedance load

Answer

because it has a very large resistance gain (= R0/R1)

Question 7

In common-collector configuration, which is also sometimes called grounded collector configuration, collector terminal

Accepted Answer

is at ground point for AC purposes

Answer

is at ground potential

Answer

is virtually earthed

Answer

is at ground point for DC purposes

Question 8

"In an amplifier using common-collector configuration, the voltage gain was found moving more and more closer to unity as the peak of the excitation signal was increased." Is it true?

Accepted Answer

Yes

Answer

No

Answer

It may or may not be

Answer

none of these

Question 9

If the amplifier is assembled with germanium transistor and fed with a voltage signal of peak amplitude 900 mV, the peak amplitude of output signal

Accepted Answer

is approximately 700 mV

Answer

cannot be determined unless voltage gain is known

Answer

cannot be determined unless and 10 are given

Answer

none of these