Approaches to Reducing Digital-Noise Coupling in CMOS Mixed-Signal LSIs

摘要

Digital-switching noise coupled into sensitive analog circuits is a critical problem in large-scale integration of mixed analog and digital circuits. This paper describes noise coupling of this kind, especially, through the substrate in CMOS integrated circuits, and reviews recent technical solutions to this noise problem. Simplified models have been developed to simulate the substrate coupling rapidly and accurately. A method using a CMOS comparator was proposed for measuring the effects of substrate noise, and equivalent waveforms of actual substrate noise were obtained. A circuit technique, called active guard band filtering, that controls the noise source is a new approach to substrate noise decoupling. CAD methods for handling substrate-coupled switching noise are making design verification possible for practical mixed-signal LSIs.