Bhyrav Mutnury, Senior Engineer, IBM
Daniel N de Araujo, Senior Technical Services Engineer, Ansys
Greg Pitner, Senior Technical Services Engineer, Ansys
Minhong Mi, Ansys
Nam Pham, IBM

Prediction of radiation from multilayer circuit boards is an important problem which is of interest to high speed digital system designers. In particular, signal mode conversion as the result of undesired imbalances in the board interconnects plays a significant role in the generation of noise emission. These undesired imbalances also eat into the signal integrity margins making the system more susceptible to failure. In this paper, we investigate methods for modeling common/differential mode conversion from relatively complex interconnection structures in a multi-Gbps system using a systematic approach. The strong correlation of good signal integrity practices to electromagnetic emission is discussed with emphasis on key structure contributors. The electrical modeling of key contributors (such as vias, connectors, traces, manufacturing techniques, etc.) to undesired mode conversion effects is also presented in a telecommunication blade environment.