What do you mean by 1 psec jitter? Do you mean Rj, Dj, Tj? Are you measuring Time Interval error, cycle-to-cycle, or something else?
I would recommend doing some reading. You can start at
Scroll down to "Key Library Information" and download (and read) all of the White Papers and Application notes.
One of the first things you'll find is that it's probably impossible to measure 1psec of jitter. As with any other measurement, there is the concept of the smallest measureable unit. In the jitter world, this is the Jitter Measurement Floor, and typical values are 80 fsec to 2 psec.
I personally can't imagine anything going on in an FPGA that would be affected by 1 psec of jitter. More info would be advisable.
GS