Analysis for radiated emission of differential signal transmission system

摘要

In many cases serious radiated emission are observed from a model of signal transmission through cable connected between printed circuit boards (PCBs) that is often seen in electronic equipment. Recently it increase that differential signal transmission system with low amplitude is adopted to control radiated emission from the model. But it has not yet made clear about the behavior of the radiated emission from the system. In this paper, we have studied for the mechanism of the radiated emission from differential signal transmission system by using test-unit composed of cable and PCBs. It is made clear that all system of "PCB-Cable-PCB" is driven as antenna by common-mode voltage output from LVDS driver IC. And we tried quantitative interpretation about the behavior of radiated emission spectrum for some kind of end termination of differential signal transmission line. We show above-mentioned contents from results of measurement and electromagnetic field simulation.