The audio amplifier is a device that reconstructs the input audio signal on the output element that produces the sound. The reconstructed signal volume and power level must be ideal-truthful, effective and low distortion. The audio range is about 20Hz to 20000Hz, so the amplifier must have a good frequency response in this range (smaller when driving a frequency-limited speaker, such as a woofer or a tweeter). Depending on the application, the power level varies greatly, from the milliwatt level of headphones to the several watts of TV or PC audio, to the tens of watts of “mini” home stereo and car audio, to the more powerful home and commercial audio The system’s hundreds of watts are large enough to meet the sound requirements of the entire cinema or auditorium

Audio amplifier is one of the important components of multimedia products and is widely used in the field of consumer electronics. Linear audio power amplifiers have always dominated the traditional audio amplifier market due to their low distortion and good sound quality. In recent years, with the popularization of portable multimedia devices such as MP3, PDA, mobile phones, and notebook computers, the efficiency and volume of linear power amplifiers have been unable to meet market requirements, while Class D power amplifiers have become more and more popular for their high efficiency and small size. Favor. Therefore, high-performance Class D power amplifiers have very important application value and market prospects.

The development of audio amplifiers has experienced three eras: electron tube (vacuum tube), bipolar transistor, and field effect tube. The tube audio amplifier has mellow sound, but it is bulky, high power consumption, extremely unstable, and poor high-frequency response; bipolar transistor audio amplifier has a wide frequency band, large dynamic range, high reliability, long life, and high frequency response Good, but its static power consumption and on-resistance are very large, and the efficiency is difficult to improve; the FET audio amplifier has the same mellow tone as the electronic tube, and its dynamic range is wide, and more importantly, its on-resistance is small , Can achieve high efficiency.