[time-nuts] femtosecond jitter anyone?

[Chris Mack / N1SKY]

Hello fellow time nuts,

Have a project here with an OCXO from Vectron at 38.88MHz being the  
"jitter reference" for a DSP based PLL.

The Vectron part has a little bit of close-in phase noise below 12kHz  
of BW.   Is there a way to filter this, say by driving an external  
(temperature stabilized) crystal "backwards" (in the non-traditional  
sense rather than using the crystal to provide a clock for a system)  
and recovering the signal?

Also the output of the Vectron part is square and it would be ideal  
to distribute a sine wave....

I cannot find traditional crystal filters that have a direct center  
at 38.88MHz also with any usable bandwidth (for the close-in skirt)  
for this application.

The DSP PLL has "femtosecond" jitter capabilities depending on how it  
is applied, e.g., for SONET and the like and also depending upon  
measurement BW used.  Also the jitter reference comes into play here  
as well....

For the sampling application this is being used for, it would be  
ideal (by design) to keep the timing uncertainty below 0.45ps or so...

Any thoughts?

Cheers,
-chris
N1SKY
--
Chris Mack
Electrical Engineer / RF Engineer / Software Engineer / Mastering  
Engineer
Temple, NH