RE: Jitter method for serial PMDs
Hi Rohit
For the 2^23-1 PRBS pattern and DJ, you probably need a TimeIntervalAnalyzer
or a CDR with large bandwidth and measure on the recovered clock. However,
the CDR spectrum will onsly show jitter within the PLL bandwidth.
You may as well try with a a shorter pattern, then you can sometime se
multiple traces on the oscilloscope (using color persistence).
Benny
-----Original Message-----
From: Rohit Mittal [mailto:RMittal@oni.com]
Sent: 9. april 2001 23:44
To: 'Christensen, Benny'; _Serial PMD Ad Hoc Reflector (E-mail)
Subject: RE: Jitter method for serial PMDs
Thanks, Christensen for your reply. In answer to one of your questions
below, yes I was measuring broadband jitter (ie with a scope) and not
narrowband jitter.
I am also interested in finding out the frequency characteristics of these
jitters. I can easily find RJ using the spectrum analyzer by putting in
1010...FYI, the spectrum, as expected, is like a VCO spectrum, sloping down
from the center. Hence, it is concentrated at low frequencies.
Now, I wanted to do the same for DJ. However, it doesn't seem possible using
a spectrum analyzer, right? Firstly, its a large scale phenemonon.
Secondlyh, I am inputting 2^23-1, which does not have a spectrum which is
easy to quantify accurately.
Any ideas? A theoretical analaysis would be welcome too otherwise I can do
the experiment and feed the results back to this group
thanks
Rohit