Prediction of Near Magnetic Field Distribution of Switching ICs

Abstract

This work presents a method to predict the near magnetic field distribution on the digital switching circuit mounted on PCB using co-simulation of circuit and electromagnetic fields. The proposed method first obtains the normalized near field distribution by exciting the signal and power ports of the switching circuit using sinusoidal sources. Then the real near magnetic field distribution is determined by weighting the normalized field distribution using the current spectrum of the switching circuit. To confirm the proposed method, a switching IC with a ring oscillator and a output buffer is fabricated and measured in the form of chip-on-board. The surface magnetic field distribution is measured using a magnetic probe above the PCB and compared with the simulation results. Experimental results show the correspondence between simulation and measurement results within 10 dB up to fifth harmonics.