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AR# 65838

LogiCORE DisplayPort v6.1 - Can the UltraScale DisplayPort Sink support sources using Spread Spectrum Clocking (SSC) when receiving at 1.62 Gbps?

Description

Can the UltraScale DisplayPort Sink support sources using Spread Spectrum Clocking (SSC) when receiving at 1.62 Gbps?

Solution

Starting with the DisplayPort v6.1 Sink, it is required to use the DP159 retimer so that sources with Spread Spectrum Clocking (SSC) can be supported.

Without DP159, the DisplayPort Sink will see inconsistent results when receiving video from GPUs at all line rates that have low-frequency jitter that cannot be tracked by the GTs.

Because of the internal CPLL limitation in UltraScale devices, the documentation shows that for 1.62Gbps, using the forwarded clock by the DP159 is not supported.

Instead, an external fixed clock of 162MHz is required.

For an UltraScale device in 1.62 Gbps mode:

  • The DP159 retimer is still used to clean the random jitter on the incoming data.
  • A Local Ref Clock (270 MHz) is used instead of the clock forwarded clock by the DP159 retimer
  • The CRD has been specifically tuned for 1.62 Gbps

Please see the DisplayPort product guide PG064 for more details.

AR# 65838
Date Created 11/03/2015
Last Updated 11/17/2015
Status Active
Type General Article
Devices
  • Kintex UltraScale
  • Virtex UltraScale
Tools
  • Vivado Design Suite - 2015.3
IP
  • DisplayPort