用于音频功放的数字上采样滤波器设计

Design of Digital Upsampling Filter for Audio Amplifier

设计了一种用于音频功放的数字上采样滤波器,通过可配置的多级插值系统将多种采样率(44.1 kHz、48.0 kHz、88.2 kHz、96.0 kHz、176.4 kH、192 kHz)的音频信号采样频率提高到6.144/5.6448 MHz,解决了目前功放芯片只能兼容某种单一采样频率信号的问题,极大提高了音频功放的性能和音频功放芯片的灵活性。通过对半带滤波器算法结构研究,依据半带滤波器的特点,在不损失性能的前提下改进滤波器结构,使半带滤波器的资源消耗减少3/4。最终经Matlab和Modelism仿真验证分析,上采样率器带内纹波损失低于0.03 dB,各级滤波器阻带衰减-80 dB左右,滤波器最大群延时为2.052 ms,输出波形光滑,满足实际使用需求。

A digital up sampling filter for audio power amplifier is designed.The sampling frequency of audio signals with multiple sampling rates(44.1 kHz,48 kHz,88.2 kHz,96 kHz,176.4 kHz and 192 kHz)is increased to 6.144/5.6448 MHz through a configurable multi-level interpolation system,which solves the problem that current power amplifier chip can only be compatible with a single sampling frequency signal and greatly improves the performance of the audio power amplifier and the flexibility of the audio power amplifier chip.Through the research on the algorithm structure of half band filter,according to the characteristics of half band filter,the filter structure is improved without loss of performance,so that the resource consumption of half band filter is reduced by 3/4.Finally,through Matlab and modeling simulation,the ripple loss in the band of the up sampling rate is less than 0.03 dB,the stopband attenuation of the filters at all levels is about-80 dB,the maximum group delay of the filter is 2.052 ms,and the output waveform is smooth,meeting the requirements.