Digital power amplifier is similar to DC-DC switching inverter circuit. After the input audio analog signal is modulated by PWM circuit, it forms a pulse chain whose duty ratio is proportional to the input signal.
The high-frequency components are amplified by the switch circuit, filtered by the low-pass filter, and the amplified input signal waveform is restored and played by the speaker. Fig. 2 is a typical circuit of class D amplifier, which is connected by FET H bridge.
Because of the advantages of power consumption and volume, digital power amplifier is first applied to car audio with limited energy and active subwoofer with high requirements. With the rapid development of consumer products such as DVD home theater, mini speaker system, set-top box, personal computer, LCD TV, flat panel display and mobile phone;
In particular, the emergence of some new sound source specifications with high sampling frequency, such as SACD and DVD audio, and the evolution of sound system from stereo to multi-channel surround system have accelerated the development of digital power amplifiers. In recent years, the price of digital power amplifier has been declining, and patents in this field have emerged one after another.