Cavity model applied to power/ground plane structures

Power/ground plane structures are usually used in the multilayer printed circuit boards (PCBs) for digital circuits and systems. Due to the very small thickness compared with the PCB dimensions, the planes behave somewhat like resonators, so that a signal at some point of the PCB may couple strongly to another via the cavity for certain resonant frequencies. In practical cases, switching states in the digital circuit cause abrupt changes of currents from the power plane, inducing delta-1 noise in radial wave modes to propagate to any part of the PCB, and produce interference or even system malfunctions. The paper presents a modal analysis and simulation results of the power/ground planes in PCBs based on a simple cavity model with experimental verification. This frequency-domain approach can acquire some impedance values directly that can be very useful in primary board-level designs for high-speed digital circuits and systems. By using model order reduction techniques, the frequency data can also be used to construct the macro-models in SPICE usage for further waveform simulations.