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The Designer's Guide Community Forum › Design Languages › Verilog-AMS › Spectre vs Hspice for VerilogA

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Spectre vs Hspice for VerilogA (Read 7832 times)

newic Senior Member Offline 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 Community Fellow Offline Posts: 615	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 Senior Member Offline Posts: 138	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 Senior Fellow Offline Posts: 1999 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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newic Senior Member Offline Posts: 138	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 Community Fellow Offline Posts: 615	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. B O E
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newic Senior Member Offline Posts: 138	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 Community Fellow Offline Posts: 615	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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