Estimation on magnetic near field noise from PCB by FDTD implemented nonlinear switching transistor

The wideband electromagnetic noise radiated from PCB model driven by a switching device is one of the EMI problems. To estimate the noise radiation quantitatively, a switching transistor is modeled by the FDTD method by using Ebers-Moll equivalent circuit, and its parameter is determined by simple measurement. The magnetic near field noise is calculated by FDTD method implemented switching transistor. The calculated result of the switching voltage by FDTD method corresponds to the SPICE and experimental results. The magnetic near field noise, when the 3 MHz clock pulse is applied to the source, is calculated by FDTD method and measured and it is realized that the low frequency noise, less than 200 MHz, is large when compared with radiation efficiency S/sub 21H/. The noise simulation method using the FDTD method for the implemented switching transistor can be a very useful tool to estimate the noise radiation in the next step.