( ESNUG 455 Item 4 ) -------------------------------------------- [06/29/06]
Subject: Users on Apache PsiWinder
TIRE KICKERS -- PsiWinder is still at the evangelical sales stage where
people are trying to figure out what it is and if they really need it or
not. No biggie there; it was introduced only last year.
"In your view, how does the new (DAC'05) PsiWinder rate? What are its
competitors? Is it a useful tool or a waste of money?"
PsiWinder is an interesting tool. It allows us to take dynamic
IR-drop VDD/VSS waveform, at each node in the circuit, into
SPICE-like simulation to get a more realistic timing analysis
for clock jitter and skew. I don't know of any other tool that
can even do it.
- [ An Anon Engineer ]
We used PsiWinder to analyze the concurrent impact of SI and power
integrity for both the clock tree and critical paths. It has been very
useful in helping us get accurate delay, slack and skew information
before tapeout. Since our power integrity data comes from RedHawk, it
doesn't take extra time to prepare it for PsiWinder.
PsiWinder is based on Apache's NSPICE; we chose it for its accuracy and
performance. When we compared its results with HSPICE, the difference
was within 2%. Our design is 0.13 um.
Our clock tree information
levels # buf/inv # leaf node
CLK1 11 781 40,269
CLK2 10 316 15,714
CLK3 12 1296 76,767
CLK4 12 1004 58,096
HSPICE (golden) vs. PsiWinder NSPICE
diff. diff. diff. max. min. ave.
max. min. ave. ratio ratio ratio
CLK1 60 ps 42 ps 51.4 ps 1.84% 1.30% 1.61%
CLK2 51 ps 25 ps 38.5 ps 1.35% 1.77% 0.91%
CLK3 69 ps 23 ps 43.9 ps 2.01% 0.68% 1.29%
CLK4 67 ps 18 ps 40.1 ps 1.93% 0.53% 1.18%
For the timing path report, PsiWinder generates a PrimeTime incremental
report and appends a modified timing delay (based on their SPICE
simulation result) directly after the PT delay number. We can easily
see the differences using this report.
It generates a file which clearly lists detailed information about every
net and cell (delay, total cap, coupling cap, slew, power drop, and
ground bounce value). Because PsiWinder is integrated with RedHawk, we
can trace the path directly in RedHawk's GUI environment.
PsiWinder has a convenient way to generate SPICE deck and analyze PI and
SI noise effects on timing. It generates information on "input
sensitization", "vector generation", and "noise signal alignment through
iterative simulation", which would be time consuming to create manually.
A PsiWinder drawback is that Apache still lacks a STA engine to analyze
whole timing paths like Synopsys PrimeTime, so we need to choose which
critical paths to analyze, which can be difficult. Their STA engine is
not able to accurately interpret the timing impact combining by PI & SI
noise effect. Even so, PsiWinder's results are usually consistent with
HSPICE and PrimeTime.
- [ An Anon Engineer ]
We use PsiWinder to check critical paths. It is as if our Focused Ion
Beam (FIB) ASIC timing change was done after the issue was found in the
production of the chip. This saves a lot of money and also brings up
the mass production yield with first pass success. To use PsiWinder,
your SPEF must contain the base cap and the net node to net node
coupling capacitance for accurate SPICE modeling. The best switching
scenario can be created using the statistical algorithm and RedHawk's
timing-aware function by means of a PrimeTime report for the critical
paths. Once the Vdd and Vss waves are reviewed as accurate, and the
values applied to each cell in the critical path, your timing margin
can be reviewed and adjusted with SPICE accuracy. It should one day
replace the need for a FIB ECO timing modification.
- Lief Erickson of VikingStarTech, Inc.
I did not try it yet, but it seems to be a powerful tool as it links
power integrity, with signal and timing integrity in a more intuitive
way.
- [ An Anon Engineer ]
Will try it if I had a chance.
- [ An Anon Engineer ]
No comment yet.
- [ An Anon Engineer ]
Not used yet but we are planning on doing it
- [ An Anon Engineer ]
Seems like a useful tool but don't have it inhouse.
- [ An Anon Engineer ]
Although we don't use PsiWinder, our introduction to it piqued our
interest. We'd be even more interested if it eventually morphed into
a full-design PI-SI analyzer.
- [ An Anon Engineer ]
Didn't used it.
- [ An Anon Engineer ]
We adopted PsiWinder for PI & SI concurrent analysis on clk tree and
critical paths. It helped us get accurate delay, slack and skew
information before project tapeout.
- [ An Anon Engineer ]
Dunno
- [ An Anon Engineer ]
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