( ESNUG 394 Item 12 ) -------------------------------------------- [05/29/02]
Subject: ( ESNUG 389 #12 ) Silicon Metrics 'Path' PrimeTime/SPICE Analysis
> We used Hspice to model the effects of crosstalk on a part of our design
> and a simple testcase from Synopsys. We first compared our Hspice results
> to our regular Primetime results (no crosstalk), and once those numbers
> were verified, we compared PrimeTime-SI and Hspice results.
>
> We used the new write_spice_deck command to write out a SPICE deck for a
> specific timing path in our design. This SPICE deck included all of the
> nets and cells in the timing path as well as the nets and drivers for the
> crosstalk aggressors affecting this path. Unfortunately, this testcase
> was much too complicated. There were too many aggressors on the same net,
> and a comparison with the PrimeTime-SI results would not be practical. A
> simpler testcase was needed.
>
> - Ryan Hyma
> AMD Austin, TX
From: Art Arizpe <aarizpe@banderacom.com>
Hi John,
I noticed that Ryan Hyma uses a manual process for comparing STA results
with SPICE. We use a tool from Silicon Metrics called Path that does the
same thing but it's automatic.
Path runs with Primetime. After I select my critical paths using PrimeTime
TCL, Path spits out SPICE decks, sends them to multiple machines for
simulation, and brings the results back into PrimeTime. It has reports to
compare STA to SPICE for delay and slew. I know PrimeTime has a
write_spice_deck command, but this is much better.
It's easy to use and the incremental and debug analysis capability really
helps during tapeout crunch. It's the first release, so it doesn't have
lots of bells and whistles. But it looks like the they are working on the
right set of features like SPICE level SI analysis.
One place we found it very useful was for catching a tricky hold problem.
In Primetime, several hold paths showed about +10 ps of slack. On the
other hand, SPICE analysis (which included IR drop) from Path show nearly
-150 ps hold slack.
Had we not caught these before tapeout, it would have been bad.
- Art Arizpe
Banderacom Austin, TX
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