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In the 21st century , a variety of portable electronic devices has become an important development trend of electronic devices . From a mobile phone as a communication tool , the MP3 player as entertainment devices , has become almost everyone has a portable electronic device . All of these portable electronic devices one thing in common , that is, have audio output , that is, we need to have an audio amplifier ; Another feature is that they are battery-powered , all want to be able to have a longer life . Is in the context of this demand , the class - D audio amplifier is developed . Its biggest feature is the ability to maintain a minimum distortion for maximum efficiency. In this paper, by analyzing the basic principle of the Class D audio power amplifier , characteristics and factors to be considered in the design , design a fully differential input , PWM bilateral modulation, the bridge output dual-channel , high-power Class D audio amplifiers . The chip is divided into reference circuit , the front operational amplifier and PWM comparator circuit , an oscillator circuit , the gain control circuit , soft-start circuit , dead-time control circuit, the output power tube design circuit , over-current protection circuit , over-temperature protection circuit multiple functional modules and its circuit design and simulation . Chip single-channel output power up to 12W, the volume output range of -40dB ~ 36dB, efficiency up to 80% . Applied to the LCD monitor , LCD TV, speakers and other audio devices . The whole circuit is based on CSMC 0.5μm DPDM 5V ~ 18V CMOS process design, layout area of 4.5 * 4.5 mm 2 . Use the Cadence EDA software to complete the circuit design and simulation . Simulation results show that the circuit functionality and performance indicators have reached the design requirements .
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