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Spectre vs Hspice for VerilogA (Read 7882 times)
newic
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Posts: 138
Spectre vs Hspice for VerilogA
May 20
th
, 2011, 6:03pm
I tried out both Spectre & Hspice to simulate a close loop system that written in VerilogA (using cadence ADE). The results are difference. Do you think spectre result is more accurate than hspice result. Why the results have such difference?
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boe
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Re: Spectre vs Hspice for VerilogA
Reply #1 -
May 23
rd
, 2011, 10:11am
Newic,
please be more specific (see also forum guidelines). E.g. how big is the difference, what kind of system did you model, ...
B O E
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newic
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Re: Spectre vs Hspice for VerilogA
Reply #2 -
May 23
rd
, 2011, 5:22pm
since it is a close loop system( PI CDR), the difference is actually quite big (hspice default accurate setting).
Tried out several methods on hspice accuracy setting. I only able to get matched results when i set hspice RUNLVL=6 & METHOD=Gear.
There is a mismatch even i set RUNLVL=6 & METHOD=TRAP.
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Geoffrey_Coram
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Massachusetts, USA
Re: Spectre vs Hspice for VerilogA
Reply #3 -
May 24
th
, 2011, 6:58am
Some behavioral models simulate poorly because the variables the author chose aren't scaled properly, so the tolerances (appropriate for V's and I's) allow gross inaccuracies in the model variables.
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If at first you do succeed, STOP, raise your standards, and stop wasting your time.
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newic
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Re: Spectre vs Hspice for VerilogA
Reply #4 -
May 24
th
, 2011, 7:24am
I got to check my ttol setting.
Besides the ttol setting, what else could cause the difference?
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boe
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Re: Spectre vs Hspice for VerilogA
Reply #5 -
May 25
th
, 2011, 2:24am
Newic,
E.g., a simulation of a system that is close to the stability boundary may depend on the solver algorithm used and its implementation.
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newic
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Re: Spectre vs Hspice for VerilogA
Reply #6 -
May 25
th
, 2011, 2:38am
thx for the feedback. There is no stability issue here (a lot of margin).
At least for now, spectre is more accurate for a given ttol.
I think the difference can be reduced if tightening the ttol.
No time to verify this yet.
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boe
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Re: Spectre vs Hspice for VerilogA
Reply #7 -
May 25
th
, 2011, 4:52am
Newic,
A model bug can of course cause this as well.
BTW, plots would be nice...
B O E
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