CMOS Chip Design for Reduced Radiated EMI Emissions

With the supply & output current (ICC, IOL, IOH) rise times inherent in today's CMOS processes, EMI problems are present even though clock frequency & output voltage switching speed may be slow. The EMI problem is first explained, then basic theory is presented with explanation on how to use it for initial design or to fix a chip so that it has reduced radiated emissions. Actual circuit designs are given which modify the ICC, IOL, and IOH waveforms without destroying functionality or performance. Substrate noise is also reduced to benefit mixing of analog and digital functions on the chip.