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Simulators >> Circuit Simulators >> Spectre Turbo - Parasitic Reduction - Fmax
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Message started by Berti on Feb 4^th, 2011, 7:07am

Title: Spectre Turbo - Parasitic Reduction - Fmax
Post by Berti on Feb 4^th, 2011, 7:07am

When I enter a value smaller than 1 (e.g. 0.1) into the fmax option field of the spectre turbo parasitic reduction (using icfb 5.10.41), it get an error warning: "Invalid value specified for Fmax. Switching to default parasitic reduction mode."

Can the value of fmax be smaller than 1GHz? Is my formating wrong or is that just another bug? As usual, I haven't found anything in the documentation.

Thanks for help, Cheers

Title: Re: Spectre Turbo - Parasitic Reduction - Fmax
Post by Geoffrey_Coram on Feb 4^th, 2011, 10:57am

Are you sure that field has units of GHz, not Hz?

Title: Re: Spectre Turbo - Parasitic Reduction - Fmax
Post by sheldon on Feb 5^th, 2011, 8:47am

Berti,

Originally the minimum value of fmax was limited to 1GHz. In more
recent versions of MMSIM/IC, fractional values are supported.

Best Regards,

Sheldon

Title: Re: Spectre Turbo - Parasitic Reduction - Fmax
Post by Berti on Feb 6^th, 2011, 11:45pm

Thanks a lot Sheldon!

By the way, what is the actual meaning of fmax? What I mean is: Is the simulation accuracy guarantied for ≤fmax, or is fmax the maximum frequencies where parasitcs are taken into account (what would mean that my fmax in the simulation should be smaller)?

Thanks

Title: Re: Spectre Turbo - Parasitic Reduction - Fmax
Post by boe on Mar 7^th, 2011, 9:39am

Berti,
"An important input to the parasitic reduction technology is the relevant frequency of interest. The parasitic reduction algorithm tries to preserve circuit accuracy up to this frequency."
-- Cadence® Virtuoso® Spectre® Circuit Simulator and Accelerated Parallel Simulator User Guide, Product Version 10.1 (Sept 2010)

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