一款高性能Σ-Δ调制器的建模与设计  

Modeling and design of a high-performance sigma-delta modulator

作　　者：魏汇赞 薛文[1] 陆锦辉[1] WEI Huizan;XUE Wen;LU Jinhui(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094

出　　处：《现代电子技术》2018年第18期57-61,共5页Modern Electronics Technique

基　　金：国家自然科学基金资助项目(61472190)~~

摘　　要：为了满足音频信号处理中对高精度信号的需求,设计一款单环三阶一位量化CIFB结构的Σ-Δ调制器。通过对该调制器的噪声传递函数的零极点进行优化,提高调制器的精度;并通过根轨迹法对调制器的稳定性进行判定和优化,提高调制器的稳定性。根据Matlab仿真测试显示,当输入信号的带宽为20 k Hz,采样频率为5.644 8 MHz时,该调制器的峰值信噪比达到114.9 d B,有效位数为18.8 bit,最大归一化稳定输入信号幅度为-2.79 d BFS,动态范围为109 d B。这说明该调制器不但拥有较高的信噪比,同时还具有良好的动态范围,因此该调制器能够实现音频信号高精度的转换。A single-loop third-order one-bit quantization sigma-delta modulator with the structure of cascade of integrators with feedback(CIFB)is designed to meet the high-precision signal demand of audio signal processing.The zero pole for the noise transfer function of the modulator is optimized to improve the precision of the modulator.The stability of the modulator is judged and optimized by using the root-locus method to improve the stability of the modulator.The results of the Matlab simula-tion test show that when the bandwidth of the input signal is 20 kHz,and the sampling frequency is 5.644 8 MHz,the peak SNR of the modulator can reach 114.9 dB,the number of effective bits is 18.8,the amplitude of the maximum normalized stable input signal is-2.79 dBFS,and the dynamic range is 109 dB,which indicates that the modulator has not only a high SNR but also a good dynamic range,and can realize high-precision conversion of the audio signal.

关 键 词：Σ-Δ调制器 零极点优化 根轨迹法 音频信号处理 信噪比 MATLAB 

分 类 号：TN761-34[电子电信—电路与系统]