What is a Class D Amplifier

Class D amplifier refers to Class D power amplifier. The amplifier that drives the speaker by controlling the ON/OFF of the switch unit is called Class D amplifier. Class D amplifier was first proposed in 1958 and has gradually become popular in recent years.

An amplifier that drives a speaker by controlling the ON/OFF of a switching unit is called a Class D amplifier.

Characteristics of Class D Amplifiers

High efficiency

The efficiency of previous analog amplifiers stayed at around 50%, and the remaining 50% was mainly consumed as heat. The efficiency of Class D amplifiers is quite high, reaching 80-90%. Not only does it not waste power, it uses power effectively and can also obtain a larger power output. The following is a comparison chart of the efficiency of Class D amplifiers and previous analog amplifiers. It can be seen that Class D amplifiers are significantly more efficient.

Low fever

High efficiency, low heat generation. Previous high heat generation analog amplifiers had large packages and required large heat sinks, thus requiring large space. Class D amplifiers generate less heat and can be packaged in small packages. At the same time, no heat sink is required, thus saving space. The following is a comparison chart of energy loss (heat generation) between Class D amplifiers and previous analog amplifiers. It can be seen that Class D amplifiers have significantly less energy loss (heat generation).

Low power consumption

Class D amplifiers are highly efficient and generate less heat, which can reduce unnecessary power consumption. In applications powered by batteries and dry cells, they can maintain continuous power supply for a long time. The following is a comparison chart of the current consumption of Class D amplifiers and previous analog amplifiers. It can be seen that Class D amplifiers consume significantly less current.

Summary of Class D Amplifier Operation

The amplifier circuits of conventional analog amplifiers and class D amplifiers can be represented as shown below.

Analog amplifier amplification

The analog amplifier linearly amplifies the input signal. The waveform remains unchanged before and after amplification.

Class D amplifier amplification

The Class D amplifier converts the input signal into digital pulses through PWM and amplifies it. It outputs digital pulse signals and uses LPF to extract audio signals.