Although differential signaling generally provides for all return path currents, the GSSG geometry can support common-mode signals with a well-controlled return current path.Any common-mode signals that get
coupled or generated can propagate through the via (rather than being scattered) and along the transmission line to the receiver where it is terminated.
GSSG 一般只在serdes(1Gbps以上)走线中使用,如XFP,XAUI,pci expres。
而一般的差分走线因为速率较低(1Gbps以下),密度大(如SFI4.2总线),不会使用GSSG过孔。