Engineers use the word “ground” in every electronic circuit to denote some part of a system or structure that is “neutral,” or zero potential. Unfortunately, we often think of circuits and systems, especially those with both analog and digital signals, as having more than one ground. This concept gave rise to a recent discussion on a signal-integrity online community, which prompted us to write this article. Engineers and PCB designers often mention various types of grounds and methods for connecting them together. How those “grounds,” which are really return paths, connect can significantly affect a system’s performance.
The kinds of grounds mentioned in this discussion include: