Core clocks (or device clock as we call it) must be always generated with the same source as the SYSREF.
They sample SYSREF so for deterministic latency we must ensure a fixed relation between the two.
The core clock/device clock must be always an integer submultiple of the sample clock, therefore we need the 8/12 scale in case of N’12 where we use the gearbox to translate from lane rate /66 (that is not a integer submultiple of the sample clock in this case) to device clock.
Core clocks (or device clock as we call it) must be always generated with the same source as the SYSREF.
They sample SYSREF so for deterministic latency we must ensure a fixed relation between the two.
The core clock/device clock must be always an integer submultiple of the sample clock, therefore we need the 8/12 scale in case of N’12 where we use the gearbox to translate from lane rate /66 (that is not a integer submultiple of the sample clock in this case) to device clock.