EMI Analysis of Multilayer PCB Power/Ground Planes and Radiation Suppression Design by Shorting Vias
Date Issued
2009
Date
2009
Author(s)
Chang, Fu-Sheng
Abstract
This thesis focuses on the problem of Electromagnetic Interference（EMI）of Printed Circuit Board（PCB）power/ground planes, which is a crucial issue to the whole system stability in high speed digital circuit. The primary noise of power/ground planes which arises from current flowing through a via or the signal trace crossing slot lines is the ground bounce. The electromagnetic waves reflecting back and forth from edges of the substrate generate a standing wave, which gives rise to radiated emission, and is often identified as EMI. The cavity resonator model together with a new even/odd mode radiation model is proposed to explain the radiated emission mechanism. The maximum power suppression between even and odd mode radiation is derived. This thesis then employs one way of using the shorting vias to suppress the odd mode radiation resulting from the PCB edges. By analytical methods, several designing methods of shorting vias placement, including 1-column vias, 2-column parallel vias and 2-column interlacing vias are presented. EMI suppression is above 40dB and 66dB for 1-column and 2-column vias design respectively. Finally, EM simulation tool “HFSS” and GTEM Cell measurement are used to validate the accuracy of the design.
Subjects
electromagnetic interference
ground bounce
shorting vias
cavity resonator model
Type
thesis
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