[SI-LIST] Jitter Analysis
- From: Khalid Ansari <khalida@xxxxxxxxxxx>
- To: si_list <si-list@xxxxxxxxxxxxx>
- Date: Mon, 11 Feb 2002 15:07:03 -0800
Hi all,
I have a driver and receiver talking in an asynchronous
fashion at 2.64 Gbps. The driver is sending out random
data over 64 inches of PCB trace (5 mil of around 10" LC
and 8 mil rest on Backplane). There are a lot of SMAs
on the path too for connecting traces to each other. Using
TDR I determined each to be around 1.5 pF of discontinuity.
My receiver is able to pick this up even though the eye looks
completely closed due to excessive ISI (thanks to the
equilization circuitry). I am trying to look at the content of
the jitter on a WaveCrest jitter analyzer. The WaveCrest
keeps on complaining, "Measured DCD+DDJ data does not
appear to match user specified pattern. Sample:2.57e-289
Limit: 5.00e-001". When I reduce the trace length by about
20 inches then a distinguished eye can be seen due to lesser
losses. This eye I am being able to analyze using the
WaveCrest.
In past experiences has anyone seen similar behavior.
What are the limitations of the Wavecrest? I can measure
the random jitter by cutting down the trace and using the
Wavecrest but for DJ what should I do? The eye is so closed
that I can't even get a meaningful result using the histogram
on the Tek 11801 B scope.
In short, what is the best way for me to find out the amount
of deterministic jitter on my data. Any ideas will be appreciated.
Thanks in advance,
Khalid
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