From: S. Weir (firstname.lastname@example.org)
Date: Sat Mar 24 2001 - 13:47:36 PST
As mentioned earlier this week, Amherst's offers software that works with
the better Tek, and HP scopes to analyze jitter spectra that is way down
from the clock. It can be very helpful for finding problems coming from
the power system, or RF interference from other sources.
At 04:22 PM 3/23/01 -0500, you wrote:
I may as well add my view for comments, so here goes.
In today's systems, switching voltage regulator modules (VRMs) or switching
DC/DC power modules are typically used. Note that these switching modules may
or may not employ frequency dithering techniques to pass their own EMI
criteria. Unfortunately for higher frequency clocks, buffers (clock
distrubution chips), PLLs, and SERDES systems in general, the instantaneous
voltage perturbations in the delivered DC voltage will cause phase jitter.
So, while your power delivery system may allow you to pass EMC required
levels, your SERDES system may exhibit an unacceptable bit error rate (BER).
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