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. 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. Cecil K5NWA www.softrockradio.org www.qrpradio.com "Blessed are the cracked, for they shall let in the light."
