k5nwa schrieb: > At 01:57 PM 4/20/2008, you wrote: > >> Hi Dave and others - >> >> After thinking about what is going on, my question is: >> Is the 400ps spec in the datasheet another way of a spur definition? Can >> I simply see the jitter as a short-term time-delay at the output? This >> will translate the programmed nominal output frequency to another >> frequency... >> >> The CY22393 is a PLL-type system. One can set the PLL loop-bandwidth in >> a register. Unfortunately the data sheet doesn't cover this area, nor >> where optimum jitter performance would be possible. Maybe a good >> relation between quartz- and programmed output frequencies will drive >> jitter considerable down? >> >> Someone knows more? > > Depends on the nature of the jitter if its repeatable it shows up as > spurs if it's random it shows and a higher noise floor.
At the moment I think it is more spurs than noise floor. I will try to contact the electronics department on the local university. Maybe they have and allow me to use their SA. > > Took bad they didn't use the SI570 chip, it has .4 ps jitter not 400 > or approximately 1000 times less. Maybe someone will modify it someday. > I ordered samples of the SI571. Unfortunately even after weeks no response from silabs :-( On datasheet the rf spec of the SI57x devices look very good. The other side of the coin is price and power consumption. Both really heavy. That would kick them out of most mobile apps. Other comparable devices? I need at least two PLL on the chip. regards - Henry > > Cecil > K5NWA > www.softrockradio.org www.qrpradio.com > > "Blessed are the cracked, for they shall let in the light." > > > ------------------------------------ > > Yahoo! Groups Links > > > >
