[dy]

Class A amplifiers are known for their high linearity and low distortion. They operate by amplifying the input signal all the time, regardless of whether there is an input signal or not. This constant amplification results in high power efficiency but low electrical efficiency.

Class D amplifiers, on the other hand, are digital switch-mode amplifiers. They operate by switching rapidly between on and off states. The duty cycle of these switches is modulated to reproduce the input signal. This results in high electrical efficiency but can introduce some distortion. To reduce distortion, a process called Pulse Width Modulation (PWM) is often used, which makes the amplifier switch at a rate faster than the highest frequency in the input signal. This quickly alternating signal is then filtered to remove the high- frequency components, leaving the original input signal.

In short, Class A amplifiers offer high linearity and low distortion but have low electrical efficiency, while