Abstract: Based on the brief description of the principle of Σ-ΔADC and analyses of modulator's noise characteristics, the Top-down design method of modulators is introduced. Then, combining with practical requirement, this paper focuses on the discussion of designing the analog circuits in a Σ-Δ modulator. Some key of design, circuit details and simulation results are also presented.

Key words: Σ-Δ modulator, oversampling, SNR, top-down design

摘要： 在简要介绍Σ-ΔADC基本原理的基础上，分析了Σ-Δ调制器的噪声特性，并对调制器自上而下的设计方法做了介绍。结合实际的性能要求，重点对模拟电路部分设计中的关键以及设计方法进行了详细分析，并给出了有关的电路结构和仿真结果。

关键词: Σ-Δ调制器, 过采样, 信噪比(SNR), 自上而下的设计