AnsweredAssumed Answered

AD9578 has trouble locking, high jitter after lock

Question asked by vanwyk on Jul 1, 2016
Latest reply on Jul 6, 2016 by cosmolittle

I'm using the AD9578 evaluation board, and I'm experiencing what I hope is two related problems.  Once I enable the outputs, the PLLs do not lock for several minutes, if at all.  I'm unclear what does cause them to finally lock.


Even after they do lock, I'm measuring 8 ps of RMS jitter and 30ps of peak to peak jitter on a nominally 100MHz output.  I do not notice any measureable change in jitter between locked and unlocked.  I need to get that jitter down to a picosecond or less.


Is this level of jitter expected?  Do I have a faulty board?


Can you recommend a lower jitter solution?  I need two clock outputs with 1ppb resolution and >ps rms jitter.  My current plan is to keep the AD9578 and add a pair of jitter attenuators - any favorites for this application?


The two clocks will typically be within a few ppm of each other, so I'm a little worried on spurs.  Jitter situation happens without turning on the other generator though.