基于PWM的D类音频功率放大器的设计

系统旨在设计一种D类功率放大器,以高频三角波作为载波,对音频信号进行采样,生成PWM(Pulse Width Modulation)调制信号.采用高速开关管组成的互补对称式H桥电路对信号的功率进行放大,再将放大后的信号送入4阶Butterworth低通滤波器进行滤波,得到理想的音频信号.系统主要针对音频信号进行处理,对输入频率20 Hz～20kHz,振幅30～250 mV的音频信号可以实现很好的功率放大效果,最大不失真输出功率大于1W,最高效率可达到83％.还能对输入信号进行可调放大,实现信号输出功率可调.

Design of Class-D Audio-Frequency Power Amplifier Based on PWM

The system is intended to design a class-d power amplifier which uses a sort of high frequency triangle wave to process the input signal into the PWM (pulse with modulation) signal.To gain ideal output signals, the system amplifies the power of signal through the high-speed switch tube composed of complementary symmetry H-bridge circuit and filters the amplifying signal by 4-th order Butterworth low pass filter. The system can amplify the input signal and adjust output power. The main aim for this system is to process the audio signal and we would gain a satisficed result when the frequency of input signal is between 20Hz~20KHz and the amplitude of that is between 30mV~250mV.Using these technologies, the maximum efficiency of 83% can be achieved and the maximum non-distortion output power exceed 1w. According to the test results, the function and performance of the whole circuit can meet all the requirements.