Differential Vias Transition Modeling in a Multilayer Printed Circuit Board

Matteo Cocchini
Wheling Cheng
Jianmin Zhang
John Fisher
Jun Fan, Missouri University of Science and Technology
James L. Drewniak, Missouri University of Science and Technology
Yaojiang Zhang, Missouri University of Science and Technology

This document has been relocated to http://scholarsmine.mst.edu/ele_comeng_facwork/748

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A 26-layer printed circuit board including several test sites has been analyzed. All the sites have a transition from coupled microstrips to coupled striplines through signal vias. Differential measurements have been performed on some of these test sites to estimate the effect on S-parameters and eye diagrams due to via and antipad radius variation, and different lengths of via stub. The focus of this paper is on a test site with a transition from top to the sixth layer. At the same time, a physics based circuit model has been assembled in a spice-based simulation tool and a full-wave model has been generated as well. The paper will show that the process of modeling can require a series of adjustments to get reasonable results. A brief discussion about possible issues associated with fabrication tolerances is presented in the last chapter.