[10GMMF] JTOL test proposal per TP3 teleconference today
After today's TP3 conference call, there appears to be some
support for a compromise on the rx jitter tolerance (JTOL)
test (D2.0 comments 22, 225, 246 and 247).
As per Jim Mcvey's request, I would like to propose a
specific 3-point test as follows:
I propose that the test would otherwise be as specified in
the standard, i.e. there would be no stress test pulses
involved in the test.
Some of the discussion points from today's call were:
1. that the transmitter test in fact permits jitter up to
4MHz, since the CDR used in the tx test is specified to
have a 4MHz corner frequency.
2. what jitter spectra and levels are present in a "typical"
transmitter, whether these are different from what the tx
eye mask permits, and in turn whether we can rely on such
"typical" numbers as basis for an rx JTOL test.
3. the difference between qualification test for a given
module and edc chip, and manufacturing tests performed on
each produced module.
4. whether a single point at a low frequency (i.e. 40kHz) is
sufficient to ensure that the *combination* of CDR and
EDC is robust over a range of frequencies.
5. the level of difficulty involved in calibrating low levels of
6. existence of instruments capable of calibrating low levels of jitter
(microwave transition analyzer was mentioned).
7. mechanisms that may cause jitter in the 40kHz-4MHz range, including
switching power supplies and spread-spectrum clocking.
8. whether a multi-point JTOL test could or should be
combined with the rx stress test, using stress test pulses.
Lars E. Thon <firstname.lastname@example.org>
Aeluros Inc., 201 San Antonio Circle, Suite 172
Mountain View, CA 94040-1254
650-917-4113(w) 650-917-7394(f) 408-439-5914(c)