Test: Comparison of Amplifier Classes - Electronics and Communication Engineering (ECE) MCQ

Class A amplifier has the highest linearity and the lowest distortion. The amplifying element is always conducting and close to the linear portion of its transconductance curve. The point where the device is almost off is not at a zero signal point and hence its distortions compared to other classes are less.

There is no amplifier called Class I. There are only A, B, C, D, E/F, G, H, S.

Class C amplifier cannot be used for audio frequency amplifiers because of its high distortion.

Class D amplifiers use a form of PWM to control the output devices. Conduction angle varies with the pulse width and doesn’t depend on the input directly. The analog signal is converted into a stream of pulses representing the signal using a modulation technique.

Class B amplifier has a theoretical efficiency of 78.5% which higher than Class A while Class D theoretically have efficiency of 100%.

There is no amplifier called Class K. There are only A, B, C, D, E/F, G, H, S.

Class C amplifiers have high efficiency but have the poorest linearity since they only take less than 180° oscillations. They are suitable for amplifying constant envelope signals.

Class A amplifiers are the least efficient of all. A maximum of 25% theoretical efficiency is obtainable, 50% for when using transformer or with induced coupling. This wastes power, as well as increases the cost and requires higher rated output devices.

Class A amplifier has a theoretical efficiency of 50%. 50% of the energy supplied is a waste.

Class C is the most suitable amplifier type for tuning circuit and radio frequency amplification. It employs filtering and hence the final signal is completely acceptable. Class C amplifiers are quite efficient than other types.