Analysis of Capacitive Coupling and Crosstalk in the PCB of Switch-Mode Power Supplies

The increasing use of wide bandgap devices like Gallium Nitride (GaN) allows for shrinking passive components and power electronics boards thanks to the higher operable switching frequency. As sizes decrease and frequency increases, unwanted electromagnetic (EM) coupling between traces becomes more relevant, leading to crosstalk noise that can severely affect signal integrity. This paper discusses models and methods for evaluating the parasitic coupling capacitance between the traces of a switch-mode power supply. The fundamental theoretical concepts underlying its evaluation are illustrated, and guidelines are provided for its practical and reliable calculation using popular simulation tools.