Paul, I need all the freqs at the same time. 5 psec jitter means that if one examines the rising edge of a particular source and examines the rising edge of any other source in the same distribution, one will not see the riding edge move by more than a certain amount. In essence, I am interested in the RMS jitter, but that implies that that the peak to peak jitter is also under control. For example, I measured the jitter of some commercial sources using a TEK scope using several techniques. This showed me that some extra frequency spectrum leaked through and this caused circa 50% of the jitter! This topic is really a mix of SI and of good oscillator design...so I was hoping someone had to tackle this problem. The only way I can solve this problem with a commercial oscillator is at the high frequency end -- here I measure less than a picosecond of jitter. In phase, this shows a 0.5 degrees of RMS jitter. Which is about accurate to 0.3%. At the low end, Cypris makes a good chip that can do about 5 psecs...which is tolerable. I am just curious if anything else is out there that I might try. Thanks, Craig Paul Levin wrote: > Dear Craig, > > Do you need all of these frequencies at the same time, or just a few of > them at any given time? What do you mean by 5 psec jitter? RMS? Peak- > to-peak, and if so, at what probability? The answer probably lies in > voltage controlled oscillators and phase-locked loops. By the way, how > good a sinewave do you need? > > Regards, > > Paul > _____________________ > > C Deibele wrote: > >> Hi, >> >> I have a problem to solve, and am looking for a few pointers to help. >> >> I need to generate several frequencies and keep them locked together. >> The frequencies need to be stable -- which is to say to keep the jitter >> of each signal minimally low...on the order of a fraction of a >> picosecond. >> >> The frequencies I need to generate are the following: >> 2.5 MHz, >> 50 MHz, >> 350 MHz, >> 400 MHz, >> 750 MHz, & >> 800 MHz. >> >> I need sinusoids. I am nervous about the rather tight constraints on >> the jitter. Most of the parts I've used are circa 5 psecs of jitter. >> Does anyone have any pointers or perhaps a special part that can >> handle this constraint? >> >> thanks, >> >> Craig Deibele ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu