Re: [SI-LIST] : RE: Edge rates

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From: D. C. Sessions (si-list@lumbercartel.com)
Date: Mon Apr 30 2001 - 09:56:12 PDT


On Monday 30 April 2001 09:15, Dagostino, Tom wrote:

> Rates of 180 psec for 0.7 volts is really not that fast. The faster parts
> that I have seen are more like 50 psec for that voltage change.

Time to recalibrate. For the last few days I've been working on some
1.8 volt I/Os. I've tried to slow them down as much as I can, but past
about 200 ps 20%-80% they get ugly. As in, they have to be that fast
to work right. So figure (1.8 v)(0.6)/200p = 5.4 v/ns

Of course, in the fast corner the times get lower.

Alternately, you can look at the Infiniband specs, which call for swings
of 1600 mV (funny counting: the single-ended swings are 800 mV p-p)
with edge times of 125 ps 20%-80%. And that's for a cabled signal.
(This may be out of date. Infiniband is still mutating, and the specs are
not openly published.)

-- 
| The race is not always to the swift, nor the battle to the strong. |
| Because the slow, feeble old codgers like me cheat.                |
+--------------- D. C. Sessions <dcs@lumbercartel.com> --------------+

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