Class D Audio Power Amplifier Design

Compared with the traditional analog amplifier, the class D amplifier possesses large developmental foreground. The reason is the later has several characters, such as small volume, high efficiency, low distortion and high power.This project is researched in 1C design center of UESTC. Untill now, there are three prototype designed and fabricated. In the all, the first is the traditional audio power amplifier, including pulse width modulation circuit^ driver circuit power output circuit filter circuit, Improved upon which the second one is given a new drive and power output stage structure and eliminated the filter circuit. The third is attached to the output of digital audio facilities and is a "real digital amplifier" , which has been integrated into one-chip.A Class D amplifier comprises a pulse width modulator and an output stage. In this paper, we analyze the operating principle of output stage and put forward a new output stage structure, which is simple and efficient. We design and simulate every block of the amplifier including amplifier circuit^ comparator circuit triangle wave generating circuit driver circuit power output stage circuit^ over-current protection circuit> overheat protection circuit, low voltage protection circuit -. level shifting circuit check and measure and shutdown mode control circuit^ interface circuit and so on .At the same time, the feasibility of eliminating the filter is demonstrated, and the quiescent current of Class D amplifier with the low-pass filter and filterless application is measured, then Problems and performance level about the filterless applications are considered. In the design of 1C, in order to improve more the efficiency, new driver circuit is given. And for realizing the high power梙igh supply voltage, new level shifting circuit is put forward. Based on the above researching, we construct and simulate the overall circuit of analog class D power amplifier. Finally, the parasitical parameter problem of post stage layout is analyzed and solved.This paper at first introduces basic character of sound, technical indicator of audio amplifiers, classify of amplifiers and principle of class D amplifier, and compares AD PWM scheme specialty with BD. Then it presents three prototypes and their test data. Finally, from the point of view of integration of one chip circuit design and simulation data of class D audio amplifier' s every block are given, so do layout of post-circuit and finish the test work of digital audio power amplifier.