Damping of cavity-mode resonances in PCB power-bus structures using discrete capacitors

In this paper, the impact of lumped elements connected to the power-bus of high-speed printed circuit boards is investigated and a computationally efficient expression of the resulting input impedance is derived. This result builds the theoretical basis of a novel technique suppressing cavity-mode resonances within the power-bus using discrete capacitors. Guidelines for an optimized selection and placement of these capacitors are specified. The theoretical results are well confirmed by measurements.