8 - EMC grounding solutions

Abstract

This chapter explains basic and practical electromagnetic compatibility grounding (EMC) techniques. All grounds have resistance and therefore, a voltage drop between the measured ground point and any other point. With mains and other power systems, the grounding or common system is the return path for the whole system. It is found that in a series grounding system, any common point along the way to the ground is a different voltage when compared to any other point. The most frequently installed earth ground is the single point parallel common ground. It is found that one of the best ways of reducing noise on a printed circuit board is through good grounding and power distribution. All common tracks on a printed circuit board (PCB) and external devices induce noise because of their commonality. It is observed that by using a parallel single point or grid type ground as opposed to series ground, the designer can reduce the noise induced from one circuit to another on the PCB. It is suggested that the ground plane of the digital and analog circuits do not run in parallel on top of each other.