Design Of Dual-Channel Fully Differential High-power Class D Audio Power Amplifier

In the 21st century, a variety of portable electronic equipment has become an important trend in electronic device field. From the cell phone as a communication tools to the MP3 player as an entertainment device, almost everyone has become available in portable electronic devices. All of them in common is that they have audio output. In other words, there is a need for audio amplifiers in these devices; the other feature is that they are battery-powered, wished to have a longer service life. D-type audio amplifier has been developed in this background. Its most prominent feature is it can maintain the highest efficiency with the minimum distortion.Through analysis of the basic principles, characteristics and the design factors of the D audio power amplifiers, a dual-channel Class D audio amplifier was designed with fully differential input, PWM modulation bilateral and bridge output. The whole circuit was divided into several basic circuit chips, such as pre-op amp circuits and PWM comparator, oscillator circuit, gain control circuitry, soft-start circuit, the dead-control circuit, power circuit design, over-current protection circuit, over-temperature protection circuit and other Functional modules . The whole chip is a 12W efficient per channel and the efficiency can up to 80%. Stereo speaker volume is controlled with a dc voltage applied to the volume control terminal offering a range of gain from -40dB to 36dB. The chip can be used in LCD monitors, televisions, audio equipment, speakers, and so on.The whole circuit is designed on the basis of the CSMC 0.5μm DPDM 5V~18V CMOS process, its layout area is 4.5*4.5 mm 2. The simulation and verification are completed by EDA tools such as Cadence etc. According to the simulation results, the function and performance of the whole circuit can meet all the requirements.