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AR# 40810

Virtex-6 GTH - How to lock the CDR to REFCLK (local oscillator)

Description

How can I set the GTH receiver in lock to reference mode?

Solution

In normal mode, the CDR (Clock and Data Recovery) is locked to incoming data. In some cases (i.e., when the receiver is used as a simple oversampler, or when NIDRU is needed), the CDR must be locked to local oscillator.

To lock the CDR to the local reference clock, read-modify-write through the DRP interface and set RX_CDR_CTRL2_LANE[7] = '1'.
This overrides the Phase Interpolator code.

The recovered clock will now be locked to thelocal reference clock.

References:

Dynamically Programmable DRU for High-Speed Serial I/O Application Note (XAPP875):
http://www.xilinx.com/support/documentation/application_notes/xapp875.pdf

AR# 40810
Date Created 03/15/2011
Last Updated 02/08/2013
Status Active
Type General Article
Devices
  • Virtex-6 HXT