AR# 33572: Spartan-6 GTP Transceiver - GTPCLKOUT must be routed through a BUFIO
Spartan-6 GTP Transceiver - GTPCLKOUT must be routed through a BUFIO
Keywords: BUFG, BUFIO, GTPCLKOUT, REFCLKOUT, global clock
The Spartan-6 GTP Transceiver has different clocking requirements than previous Xilinx transceivers.
This Answer Record discusses how to correctly provide clocks to the fabric from the GTP.
The primary output clock from the GTP Transceiver is GTPOUTCLK and can be fed from either the output divider of the PLL or directly from the reference clock input. GTPOUTCLK needs to be fed directly to a BUFIO to be used in fabric.