From: D. C. Sessions ([email protected])
Date: Tue Oct 26 1999 - 08:26:37 PDT
"Yehuda D. Yizraeli" wrote:
> Just wondered if someone knows the nature of the requirement for
> matching of the rise and fall slope time in the USB spec.
The rise and fall times, as well as the crossover point, need to match
for two reasons:
1) Receiver performance. Mismatch would take the receiver out of its
best common-mode range and cause increased jitter. Thanks to SE0
conditions USB can't require large receiver common-mode ranges.
2) EMI. Mismatches between the rise and fall, esp. in unshielded
cables, result in large common-mode energies that radiate like crazy.
-- D. C. Sessions [email protected]
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