A methodology for accurate modeling of a pad structure from S-parameter measurements

Abstract

In this paper, we describe a novel method for modeling pad geometries via parameter extraction using S-parameter measurements. We apply the method to a square pad structure, built with a coplanar transmission line on high-resistivity silicon, and arrive at an equivalent-circuit model that represents the pad over a wide operating frequency range of 1 to 20 GHz. Two-port ABCD matrices of two transmission lines of different lengths are used to derive the model. The model is optimized and validated using circuit simulation by comparing the simulated results with those of the measurements. This method is significant for high-frequency modeling of fine-pitch wafer-level package off-chip interconnects. © 2005 Wiley Periodicals, Inc.