一种新型的级联Sigma-Delta调制器的建模设计  

Modeling design of a new cascade Sigma-Delta modulator

作　　者：曹仕林 陈红梅[1,2] 尹勇生[1,2] CAO Shilin;CHEN Hongmei;YIN Yongsheng(Institute of VLSI Design, Hefei University of Technology, Hefei 230601, China;IC Online Cooperation Research Center of Ministry of Education, Hefei University of Technology, Hefei 230601, China)

机构地区：[1]合肥工业大学微电子设计研究所,安徽合肥230601 [2]合肥工业大学教育部IC网上合作研究中心,安徽合肥230601

出　　处：《合肥工业大学学报（自然科学版）》2020年第7期927-931,共5页Journal of Hefei University of Technology：Natural Science

基　　金：国家自然科学基金资助项目(61704043)。

摘　　要：文章提出了一种新型的级联Sigma-Delta调制器。传统的级联Sigma-Delta调制器需要数字逻辑部分来抵消第1级的量化噪声,数字部分与模拟电路之间的不完全匹配将造成误差泄露。为此,有学者提出了Sturdy-MASH(SMASH)Sigma-Delta调制器以及DNC-SMASH Sigma-Delta调制器来解决误差泄露问题。该文基于上述方法对二阶Sigma-Delta调制器进行了改进,提出了一种新型的两级级联结构,使二阶调制器和额外的一位量化器级联,以此提高调制器的噪声整形。文中分析了非理想因素包括积分器中运放的有限直流增益对信噪比的影响。采用Matlab Simulink对该调制器进行建模仿真,结果表明,在过采样率为256、输入信号带宽为20 kHz时,调制器的信噪比达到114.4 dB,精度高达18.16位。A new cascade Sigma-Delta modulator is proposed.The traditional cascade Sigma-Delta modulator requires a digital logic part to offset the quantization noise at the first-level modulator,the incomplete matching between digital part and analog circuit will result in error leakage.For this reason,Sturdy-MASH(SMASH)Sigma-Delta modulator and DNC-SMASH Sigma-Delta modulator are proposed to solve the problem of error leakage.Based on these methods,a new two-stage cascade structure is proposed to improve the second-order Sigma-Delta modulator,which cascades the second-order modulator with an additional one-bit quantizer to improve the noise shaping of the modulator.The influence of non-ideal factors including the finite DC gain of the operational amplifier in the integrator on the signal to noise ratio(SNR)is analyzed.The simulation on the modulator is made based on Matlab Simulink.The results show that when the oversampling rate is 256 and the input signal bandwidth is 20 kHz,the SNR of the modulator reaches 114.4 dB and the accuracy is up to 18.16 bits.

关 键 词：级联Sigma-Delta调制器 SMASH调制器 一位量化器 非理想因素 运放的有限直流增益 

分 类 号：TN47[电子电信—微电子学与固体电子学]