Simulation of the coupling of the external electromagnetic field to PCB traces in the SPICE simulator

Abstract

In this article, a simple method of modeling and simulating electromagnetic field coupling to PCB in the SPICE simulator is presented. The method exploits two assumptions: quasi-TEM wave propagation along PCB traces and representation of an external electromagnetic noise by a plane wave. Under these assumptions, a model of electromagnetic field coupling to the PCB traces is created in the form of an active n-wire transmission line placed in an inhomogeneous (that is, three layers) medium. Next, using the method of successive approximations, an equivalent active n-port (described by means of scattering parameters) is found. This work results in formulas that express the external electromagnetic field in the form of current sources and the way they are simulated in SPICE. The method is illustrated with two examples.