01-11-2009 09:48 PM
From the MGT user guide, I know we can use the digital CDR to recover the serial data whose date rate is between 0.622Gbps and 1.25Gbps.
It looks like the serial date is sampled by 8 times(if the serial data rate is 1G, the sample rate is 8G), then the sampled 8X datas are diveded into 32/40 parreled channel, then they go into a Sample Processor and Data Tracking modul. After that, the original datas are recovered.
From the xapp225, I know the 4X oversampling is a good way to recover serial data, especailly the burst data in the GPON/EPON or the OBS(Optical Burst Switches) net system. I want to know wether the digital CDR could support to recover the burst datas in GPON/EPON or the OBS(Optical Burst Switches) net system? In another word, wether the digital CDR could reover the coming high-speed serial data in the first bit? Wehter the digital CDR is useful for recovering the burst data?
02-07-2012 06:55 AM
I have the same question, except, that I want to know about XTP and GTX Receiver in Spartan-6 and Virtex-6 devices. Those devices use phase rotation CDR.
GPON requires fast locking to incoming burst frame because it increases usable timeslot.Dedicated GPON CDR ICs can do it in 12 transitions.
I need to know if GTX/GTP CDR mechanism can lock to burst data transfer after for example 20 bit transitions or less.
Is it written somewhere?