Managing Differential Via Crosstalk and Ground Via Placement for 40+ Gbps Signaling

The use of higher frequency signaling in PCBs has brought Ground Return Via (GRV) placement to a crossroads. Signal-induced waves interacting in ground structures begin to constructively interfere, causing dramatic changes in loss, impedance, and crosstalk. After years of assuming “more is better,” the juxtaposition of wavelengths, PCB dimensions, GRV gridding, and noise concerns suggest it is time to remove GRVs instead of adding them. This session extends the authors’ DesignCon 2022 paper to the analysis of differential vias, helping attendees understand how and where to place GRVs to ensure robust signaling above 40 Gbps.

This paper was presented at DesignCon 2022.