( ESNUG 470 Item 5 ) -------------------------------------------- [10/31/07]
From Fei Yan <fyan=user domain=via-telecom not calm>
Subject: Why we switched from Synopsys PrimeTime to Incentia TimeCraft
Hi John,
I'm an ASIC Design Engineer at Via Telecom. Instead of PrimeTime, I've used
Incentia's TimeCraft for the past 6 years. Prior to TimeCraft, I had used
PrimeTime and Motive for about 4 years.
The reason I switched from PrimeTime was that it was too slow in running on
our 2 million gate design. It would take me 35 minutes with PrimeTime to
load my design database, then each time I added a constraint it took 5-10
minutes for my design database to be updated. To speed this up, I had used
10 PrimeTime licenses in parallel at the same time.
In comparison, TimeCraft was really fast. It took ~5 minutes for it to load
the same design database, instead of the 35 min it took PrimeTime! When I
added a constraint, I got the updated results within 1-2 seconds.
For accuracy, when I compared TimeCraft timing results to PrimeTime's, they
were identical. They both showed the same timing violations, for example,
a -.2 timing slack for a particular flip-flop.
Even in gate-level sim, we got a good correlation between TimeCraft and
ModelSim. TimeCraft gives us exactly the same timing results as ModelSim.
We're so comfortable with TimeCraft's results, sometimes we send our designs
straight to the manufacturer instead of waiting for all our 200 gate-level
sims to complete.
In the beginning, I had used PrimeTime as my main timing tool, and used
TimeCraft as a back-up. Because of its agreement with PT, I eventually
switched completely over to TimeCraft; I have taped-out 8 designs using
TimeCraft so far. And 10's of millions of these chips have been shipped
out to our customer's hands.
It takes 1-3 days to set up TimeCraft, depending on my design's complexity.
We need to set up the clock definition, timing constraints, multi-clock
paths, case analysis, and I/O definitions. You can ask Incentia to get an
example script. If you have PrimeTime scripts on your design, you can run
Incentia's converter scripts to transfer your PrimeTime scripts to TimeCraft
scripts. It's very easy.
Stuff I like in TimeCraft:
- Instead of writing long Perl scripts to get the delay of 2 particular
points for clock latency calculation, TimeCraft has a command in that
does that.
- Multi-task for multi-corner multi-mode analysis. Our designs have
multiple modes, e.g. function mode, reset mode, 2 scan modes (shift
and capture). TimeCraft lets us check for each mode.
- Multiple clock analysis. We have 100 clocks and TimeCraft handles
them easily, meaning that we load the design and get the correct
results immediately. Having multiple clocks doesn't slow down the
tool nor give incorrect results.
I can't comment on it's GUI; I only use it in batch mode.
Incentia's support has always been good; patches in 1-2 days, or at the most
3 days. The tool is mature now so I don't have issues with bugs anymore.
BTW, I had a patent approved on a technique using TimeCraft. The title is
"Static Timing Analyzer approach for Multi-Clock Domain" (#7134062).
- Fei Yan
VIA Telecom San Diego, CA
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