Design And Implement Of High Performance Audio Power Amplifier

Audio players such as popular CD,MP3 and DVD in the consumer electronic market have been driven for low cost and high performance headphone power amplifiers.Majority of conventional power amplifiers are designed using bipolar technology on the basis of well-known merits of bipolar transistors.Although CMOS technology offers low cost alternative,they suffer major problems such as large size in output transistors,stability issues on driving low resistive in parallel with high capacitive load at high bandwidth,noise and so on.In this paper,a Class AB CMOS audio power amplifier with unity-gain stable is presented for these problems.Firstly,the advantages and disadvantages of kinds of power amplifiers are introduced at the beginning of the paper,and a proper selected amplifier structure is used in order to satisfy the design target,and then by using the method of power and current budget,appropriate device parameter is received.The simulated result shows that when a 5V supply is used,the power is 2.2W for 4? and 2.5W for 3?,THD+N is less than 1.0%.Besides,when a headphone is used,the amplifiers work in single-ended mode and the power is 85mW for 32?,THD+N is less than 0.5%.The quiescent supply current is 11.5mA under bridge-connected mode and 5.8mA under single-ended mode.Under bridge-connected mode,PSRR is 67dB and SNR is 98dB.Under single-ended mode,PSRR is 58dB and SNR is 95dB.On the other hand,a low-power consumption shutdown circuit and a thermal-shutdown protection circuit are designed.The shutdown current is 0.7μA and the shutdown temperature is 165℃.At last,a novel inner integrated circuit structure makes the outer coupling capacitance can be omitted.Thus realizes bridge-connected and makes the volume of system even more economic.