[time-nuts] another Ebay mixup, 5370

SAIDJACK at aol.com SAIDJACK at aol.com
Thu Jun 14 13:34:35 EDT 2007


 
In a message dated 6/14/2007 10:03:40 Pacific Daylight Time,  
peterawson at earthlink.net writes:

>Just  a quick note about the HP 54720D. If you have 2 of the 4Gs plugins  
>installed & are measuring a differential ECL signal; this  combination yields
><2pS rms jitter. I spent many hours  characterizing clock gen/dist circuits 
>for the HP PARisc family of  processors; periodic noise floor confirmation
>was essential for high  confidence results.

>Regards,
>Pete Rawson  



Hi Pete,
 
That's pretty good performance!
 
I have the 2G, 4G, and the 8Gs/s plug-ins, and use the 54701A probes, but I  
only get down to about 60ps jitter even after calibrating the mainframe and  
plug-ins.
 
I typically measure single-ended outputs, but could also measure the  FireFox 
Signal Generator differential LVDS outputs. Is measuring differentially  the 
trick? Or not using the FET probes?
 
How can you get that low? What's the setup you use for this  measurement?
 
thanks,
Said



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