Noise immunity design for multilayer printed circuit boards using electromagnetic simulation

We report on electromagnetic noise immunity design for multilayer printed circuit boards using quasi three dimensional electromagnetic simulation, and its application to products. For evaluation of the electromagnetic simulation, a prototype multilayer printed circuit board was designed and tested. The coupling of its power circuit patterns on the same layer and the coupling of ground patterns on the different layers, which are thought to be fundamentally impossible to analyze with quasi three dimensional electromagnetic simulation, were measured and simulated. The measurement results of the peak level of the coupling between the patterns agree with the simulation within 10%. We confirmed that quasi three dimensional electromagnetic simulation was applicable to noise immunity design if the following conditions are satisfied: the same ground pattern was placed under the power patterns, or FG and the SG were explicitly connected with capacitors, those conditions are usually satisfied in printed circuit boards.