Abstract: With the rapid development of mobile audio equipment,conventional linear amplifiers can no longer meet the requirements of large power with low heat radiation.In this respect,class D amplifier has good performance as a switching power amplifier.However its distortion is greater than amplifiers.New control techniques to improve fidelity of class D amplifier have been studied in recent years.In this paper,the principle of D amplifiers is presented.Some control techniques including component selection,electromagnetic compatibility,and PCB layout are discussed.Using these techniques,efficiency of 90% can be achieved,and distortion can be made below 0.5%.