Design Of Small Size 400W Class D Audio Amplifier

Audio amplifiers are widely used in various types of audio equipment.People are pursuing high-fidelity amplifiers while also expecting higher efficiency and greater output power.Class D audio amplifiers gradually replace traditional analog audio amplifiers due to their advantages of small size,high efficiency,and low power consumption.At present,there are some inadequacies in the class D audio power amplifiers on the market: Larger power class D audio amplifiers are larger in size,equipment manufacturers often increase the overall device appearance due to their size,and the smaller class D audio amplifiers.Power levels often do not meet the requirements,and such devices are often used in scenarios with space limitations.Therefore,this article focuses on the research and discussion of this issue,starting with the analysis of the principle of Class D audio power amplifier,starting from the modular design,PCB design and prototype implementation.Based on simulation and experimental tests,it is shown that the Class D audio power amplifier designed in this paper has a relatively large power output while maintaining a small volume,and it is a multi-watt high-fidelity class D audio power amplifier that can be held in the hand.The main work of this paper is as follows:1.Firstly,compare the advantages and disadvantages of several traditional audio techniques to those of class D audio power amplifiers and describe the operating principles of D audio amplifier in detail.Expound several modulation modes and output stage circuits of class D amplifier,which is the base of system structure of this dissertation.The focal point is the importance of sigma-delta modulation technology to class D audio amplifier.2.Design each circuit of the class D audio amplifier.It includes pre-input circuit,drive circuit,filter circuit and protection circuit,etc.On the one hand,it is necessary to select appropriate control chips and power elements;On the other hand,the circuit parameters need to be designed in detail in order that the circuit performs optimized.A switching power supply is employed to the auxiliary circuit to provide necessary power for the amplifier.3.In order to meet the requirements of small size,this paper designed a four-layer PCB circuit board for Class D audio power amplifiers,and optimized PCB layout and routing,so that the power amplifier volume and sound effects are optimal,and a professional heat treatment.The test experiment was carried out on the prototype,including the auxiliary power module,the D-type audio amplification module and the overall performance,and the debugging of relevant parameters made the test result optimal.The designed Class-D audio power amplifier is 18 W under no-load conditions.With 8? load,the maximum transmission power is 404 W,the voltage amplification is 36.8 times,the gain is 31 dB,and the THD+N is less than 0.03%.Professional audio amplifier level.High-temperature experiment,switch machine experiment and sweep frequency experiment are performed,and the designed Class D audio power amplifier can work normally.Fully meets design requirements.Finally,this paper designs and implements a small-sized 400 W Class-D audio power amplifier with a sound quality comparable to that of a HIFI amplifier and verifies its reliability by experiments to meet the requirements of mass production.