Electrical ground looks simple on a schematic; unfortunately, the actual performance of a circuit is dictated by its printed circuit-board (PCB) layout. What’s more, ground-node analysis is difficult, especially for DC-to-DC converters, such as buck and boost circuits, which pound the ground node with large, fast-changing
currents. When the ground node moves, system performance suffers and the system radiates EMI. But a well-“grounded” understanding of the physics of ground noise can provide an intuitive sense for reducing the problem.

Reproduced with the permission of Analog Devices, Inc.