SPICE based analysis of radiation from PCBs and related structures

SPICE is used to accurately calculate the trace and ground plane currents in PCB structures containing nonlinear circuit elements. Electrical models of the structure are first made using 2D static solvers. When using 2D solvers, a hypothetical reference trace or plane far away is assumed so that imperfections in the ground planes and return paths are accounted for. After the SPICE solution, which includes the nonlinear elements, both common and differential mode radiation are calculated from the currents in the traces, planes and other parts of the structure. While being much faster than full wave EM solvers, this approach can be easily automated using a layout interface. The effect of elements such as EMI filters and of return path currents is also easily calculated.