Analysis of noise coupling result from overlapping power areas within power delivery networks

Abstract

Large area fills or entire planes constitute the backbone of the power delivery network in multi-layer printed circuit boards (PCBs). The overlapping of power areas at different voltages, though, may cause coupling among them. Full wave methods can be used to model these types of structures, and the coupling effect can be accurately analyzed by means of the finite element method (FEM), finite difference time domain (FDTD) and others. However, full wave methods are usually time consuming. In this paper, a cavity model approach is proposed to analyze the noise coupling among plane pairs in multi-layer configurations. The cavity model has analytical expressions for the impedance (Z) matrix associated with ports defined on regularly-shaped planar circuits and it is computationally efficient. The combination of such an approach with the segmentation method allows the extension of the analysis to irregularly shaped and multi-layer structures. A multi-layer PCB with three power planes is analyzed in this article by means of the proposed cavity model approach as well as a full wave FEM method. A comparison between the simulation results obtained with the two different methods is finally provided.