The Development of a Simple Equivalent Circuit of Power-Ground Plane Structure
Fengchao Xiao, Kimitoshi Murano, Yoshio Kami · 2004
When the power and ground planes in the printed circuit boards are closely spaced so that the fields between them are essentially two-dimensional, the power-ground plane can be and are often modeled as resonant cavities. Closed-form expressions for the input and transfer impedance of power-return plane structures have been developed, but the calculation is time-consuming since double infinite sum calculation is necessary. In this work, an equivalent circuit of the power-ground plane is developed based on the cavity model. The highest frequency of interest in a specific EMC/EMI problem is usually known. An analytical calculation of the number of modes that should be considered for the highest frequency of interest is discussed first. Then the development of the equivalent circuit is explained with real power-ground geometries. The analysis of the obtained circuit can be easily modeled by using SPICE, and the results are compared with the cavity model results. The application of the developed equivalent circuit in estimating power bus noise will be further investigated.