The earth or negative rail of a circuit. A large or significant mass that presents the effect of earth (ground) to a signal.
A low inductance ground system is the most important element in designing a PCB for EMC.
There are three types of ground structures on PCB:
- Minimal Ground Structure - this connects the ground points on PCB with random, high inductance connections to other ground points.
- Ground Grid - this provides many low inductance paths for current to return to its source.
- Ground Plane - the lowest impedance conductor that serves as a current return and a signal reference.