用于数字D类放大器的双边PWM调制模块

Double-edge PWM modulator for digital class-D amplifiers

文中介绍了一种双边PWM调制的数字D类放大器调制模块,使用伪自然采样法消除谐波失真。该伪采样算法是将牛顿-拉夫森迭代法和多项式逼近法相结合而形成的。近年来,虽有较多关于前沿PWM调制(LEPWM)和后沿PWM调制(TEPWM)的数字D类放大器的文献,但基于双边PWM(DEPWM)调制的数字D类放大器方面的文献较少。因此本文利用现有的噪声整形技术,基于牛顿-拉夫森迭代法的伪采样算法等实现了一种用于数字D类放大器的双边PWM调制模块,并使用FPGA搭建了一个24位立体声数字音频D类放大器调制系统。经测试,该调制系统THD+N@6 kHz性能达到-80.5 dB。

This paper introduced a double-edge PWM modulator for digital class-D amplifiers, which used pseudo sampling algorithm to reduce the harmonic distortion, the pseudo sampling algorithm is based on Newton-Raphson method and polynomial approximation method. Although many works about single edge PWM modulation scheme have been done recently, but little work are reported on the design of the DEPWM based digital audio amplifier. In this paper we applied a double-edge PWM modulator for digital class-d amplifiers, using well known noise shaping technology and pseudo sampling algorithm. Also, a 24-bits stereo digital class-d amplifier’s modulation module was implemented based on FPGA. After testing, the THD＋N@6 kHz of this module has reached-80.5 dB.