Investigation on Degradation of Common Mode Noise Suppression with Electrostatic Discharge Protection Array

In this paper, it is proposed that the electrostatic discharge protection devices may degrade the common-mode noise suppression. The mode conversion of ESD protection devices for single and multiple differential transmission lines are investigated. Experiments are set up to measure the scattering parameters and common-mode current of common-mode filter cascading different ESD protection devices. From the experimental results, the cases with four-line ESD protection array perform worse mode conversion and common-mode noise suppression.