Parasitic modes on printed circuit boards and their effects on EMC and signal integrity

Abstract

In this paper, parasitic modes, such as slotline, parallel plane, and surface wave (SW) modes, commonly found on printed circuit boards (PCBs) will be analyzed and their effects on electromagnetic compatibility (EMC) and signal integrity will be discussed. The analysis is based on numerical simulations using the finite difference time domain (FDTD) method which will be shown to be very well suited for rigorous modeling of parasitic mode effects. EMC and signal integrity problems discussed include power loss, crosstalk, ground bounce, and free space radiation. Design guidelines for improved EMC and signal integrity are derived from the results obtained. Comprehensive simulation and characterization of SWs using FDTD is presented for the first time.