SMD Footprint Optimization - SMD Footprint Optimization - XAPP1392

PCB Channel Design Guidelines for 112 Gbps GTM Transceivers (XAPP1392)

Document ID
XAPP1392
Release Date
2023-05-23
Revision
1.0 English
  • Another significant discontinuity on the link is the footprint of the SMD, such as AC coupling capacitors, board-to-board connectors, and BGA pads.
  • Generally, the footprints show excess capacitance with the combination of dielectric thickness to the reference plane and footprint geometries. Thus, the reference plane beneath the SMD pads should be voided to remove the capacitance.
  • Both an optimal cut-out depth and cut-out size (width, length, and radius) that minimize the return loss of the structure should be identified.