GROL Amplifier and Oscillator Circuits 3

Question 1

What is the theoretical maximum efficiency of a Class A power amplifier?

Accepted Answer

50%

Answer

25%

Answer

78.5%

Answer

100%

Question 2

Crossover distortion in a Class B push-pull amplifier is caused by:

Accepted Answer

A dead zone near zero crossing where neither transistor conducts

Answer

Excessive supply voltage applied to the output stage

Answer

Mismatched transistors in the push-pull pair

Answer

Insufficient bandwidth of the output coupling transformer

Question 3

Why are Class C amplifiers used for RF power amplification but not audio amplification?

Accepted Answer

Their high efficiency works with a resonant tank circuit that reconstructs the full sine wave

Answer

They amplify both positive and negative half-cycles equally well

Answer

They are the most linear amplifier class available

Answer

They introduce less noise than other amplifier classes

Question 4

The conduction angle of a properly biased Class A amplifier is:

Accepted Answer

360°

Answer

Less than 90°

Answer

Exactly 180°

Answer

Between 180° and 359°

Question 5

Class AB amplifiers are preferred over Class B in high-fidelity audio applications because they:

Accepted Answer

Reduce crossover distortion while maintaining better efficiency than Class A

Answer

Operate at 100% efficiency

Answer

Provide higher output power than any other class

Answer

Eliminate the need for bias circuitry

Question 6

Which amplifier class is most appropriate for amplifying a single-sideband (SSB) suppressed-carrier signal?

Accepted Answer

Class A or Class AB, for linear operation

Answer

Class C, for maximum efficiency

Answer

Class D, for switching operation

Answer

Class B only, because of its push-pull configuration

Question 7

The conduction angle of a Class C amplifier is:

Accepted Answer

Less than 180°

Answer

360° — the transistor always conducts

Answer

Between 180° and 360°

Answer

Exactly 180°