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Mitigating the effects of cavity resonance in ceramic millimetre wave packages

by William Sitch, B.Eng.

A Master of Applied Science thesis submitted to the Ottawa-Carleton Institute of Electrical and Computer Engineering at Carleton University

Abstract:

This thesis presents an evaluation of practical resonance mitigation techniques in complex millimetre-wave ceramic packages. The fundamental aspects of cavity resonance are examined and analytic solutions are reviewed. Four resonance mitigation techniques are proposed and developed: modifying package geometry or materials, introducing microwave absorber or resistive films, relocating excitation sources, and disturbing resonance field distributions. Ansoft's HFSS, a three-dimensional finite element method simulator, is used to model the cavity resonance problems. The obtained results are compared to analytic solutions and experimental measurements.

The mitigation techniques are evaluated in two packages designed by Nortel Networks' Modules and Advanced Packaging group. The four techniques are considered with emphasis on cost and time effective application in a post-design automated manufacturing process. Modifications are applied to the package models and the effectiveness of each technique is determined. Two of the techniques are physically implemented and both successfully eliminate resonance-induced amplifier oscillations. Simulation and measurement data are summarized and pre- and post-design resonance mitigation techniques are recommended.