Analysis of radiation caused by SSN and transmission line by combining the equivalent circuits of active IC into FDTD

Abstract

Simultaneous switching noise (SSN) caused by transient currents degrades the signal integrity (SI) and electromagnetic interference (EMI) performance of high-speed digital circuits (HSDC). In order to analyze these effects, an accurate full-wave modeling approach, which includes active devices and passive interconnects (including power and ground planes), is required. We link the equivalent circuit of an active IC into an FDTD algorithm by the equivalent current-source method (ECSM). The radiation behavior of the switched IC on PCB circuits can thus be investigated. It is found that two mechanisms dominate for the radiations of the switched IC. One is the GBN (ground bounce noise) radiation and the other is the signal trace radiation. The interaction between them and an elimination method is discussed.