∑-Δ模数转换器在数字万用表专用芯片中的应用研究

以一阶调制器为例介绍∑-Δ模数转换器(Sigma-Delta ADC)的原理、噪声能量分布和有效位数等性能指标;在此基础上详细介绍应用于数字万用表芯片中的Sigma-Delta ADC,具体分析该ADC的主信号流程以及开关电容积分器和一位模数转换器的电路结构;给出±Δ电路、低通滤波器和数字梳状滤波器的结构。通过这些内容介绍,以便更深入地了解这一类ADC应用在DMM芯片中需要考虑的电路结构设计和性能指标要求。

Taking the first-order Sigma-Delta modulator as an example, the principle, noise energy distribution and effective digits of Sigma-Delta ADC are introduced, and on this basis, Sigma-Delta ADC used in digital multimeter chip is introduced in detail, the main signal flow of ADC and the circuit structure of switched capacitor integrator and one-bit analog-to-digital converter are analyzed in detail, and the structures of ±Δ circuit, low-pass filter and digital comb filter are given. Through the introduction of these contents, in order to further understand the circuit structure design and performance requirements that need to be considered in this kind of ADC application in DMM chip.