( ESNUG 349 Item 3 ) --------------------------------------------- [4/18/00]
Subject: ( ESNUG 348 #6 ) Hey, Avanti Mars XTalk Is Crap On Cross-Cap, Too
> So now we know we've got a cross-capacitance problem, and we know we can't
> just blindly jam buffers in to fix it, so what do we do? We go check out
> the signal integrity option on Cadence Silicon Ensemble.
> ...
> 2. Its flagging over 1000 noise violations in a few hundred K gates
> of logic. Over 1K noise violations in < 9mm^^2 of randomly
> routed die? Gimme a break! Simulation showed that SE was
> over-estimating noise by > 100%. It was using a slew rate
> less than half of the actual slew rate. Its hard to say how many
> real noise violations are in there, but my simulations are saying
> my usual layout topologies ought to give me < 10 noise violations
> per 100K gates *usually*. Not 1000!
> ...
>
> All in all, I feel a lot of bad silicon coming on...
>
> - [ Born To Run ]
From: [ Born To Lose ]
John, please keep me anon.
So [ Born To Run ] thinks Cadence's Silicon Ensemble is clueless on
cross-cap? Just tell him to be glad he's not trying to run Avanti's Mars
XTalk Router. Mars XTalk also has a rinky-dink noise model that comes up
with over a thousand violations for a few hundred K gates. But then it
rips them up and tries to re-route them. Oh yeah, that's gonna close.
Not!
Between what I've seen of Avanti on cross-cap and what I read in his letter
about Cadence, it really makes me wonder how good these guys are at deep
sub-micron design. I mean, if I can run a noise simulation and find out
they're over-reporting noise, why can't they figure that out? Did they not
run the simulations, or did they set them up wrong? Both options are a
little scarey.
Anybody out there seen anything working on cross-cap? I hear Frequency's
got some Copernicus thing that's supposed to handle cross cap. Does it
work? Does it take forever? Any stories anyone can share on ESNUG?
- [ Born To Lose ]
|
|
