AR# 34138: Virtex-6 FPGA GTX Transceiver Wizard - Phase alignment not correct in hardware while using tx_sync module
Virtex-6 FPGA GTX Transceiver Wizard - Phase alignment not correct in hardware while using tx_sync module
When using the tx_sync module generated by the GTX Transceiver Wizard, phase alignment might not occur correctly with the default parameter settings. This Answer Record discusses how to work around the problem.
When implementing the example design or any other design utilizing the tx_sync module, ensure that the SIM_TXPMASETPHASE_SPEEDUP attribute is set to 0. This attribute is intended to speed up the execution of the phase alignment state machine for simulation purposes, but if left = 1, it completes too quickly and might cause unexpected phase relationships on the TX output data or even data errors.