A GMSL Power over Coax (PoC) filter blocks the frequencies used by the GMSL link to allow DC power to be injected, then extracted from the cable at each end. This allows both power and data transmission over the same coax cable. The schematic below shows the PoC filter:
The GMSL coax link has a 50ohm characteristic impedance, and it is important to minimize reflections on the cable. To do that, make sure the PoC inductor and resistor that connect to the GMSL link (L1 and R1) are perpendicular to the trace. L1 and R1's pads should be right on top of the GMSL link to avoid creating stubs. Use the layout below as a reference for laying out the PoC components.