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Impedance setting for ports in Spectre

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Be aware, when using ports in Spectre simulations, a real and imaginary impedance can be defined in the properties menu for the device. When a reactance is specified, this imaginary part is valid only when running small signal analyses like sp, ac, and noise. The reactance will give erroneous results if pss, psp, and pnoise analyses are run. We are reporting this to Cadence as an action item.


Originally posted in cdnusers.org by jmedina
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  • Andrew, In theory it seems there is agreement. The reactance should be ingnored when running a time-based analysis. The documentation even states this. But, a plot of S11 after running a PSP analysis (with the PSS using shooting method) results in an incorrect result when a reactance is defined in the port element. Trying to run a PSP analysis (with PSS using flexible balance)fails because the PSP never runs stating the flexible balance is not supported. Error found by spectre during PSP analysis `psp'. FB small signal currently only handles ac, xf, noise and stb So, going back to the shooting method and removing the reactance from the port element, PSS give the proper and expected result. All we are saying is the reactance is not truly ignored as it should be. Cheers, Kris


    Originally posted in cdnusers.org by kdonate
Reply

  • Andrew, In theory it seems there is agreement. The reactance should be ingnored when running a time-based analysis. The documentation even states this. But, a plot of S11 after running a PSP analysis (with the PSS using shooting method) results in an incorrect result when a reactance is defined in the port element. Trying to run a PSP analysis (with PSS using flexible balance)fails because the PSP never runs stating the flexible balance is not supported. Error found by spectre during PSP analysis `psp'. FB small signal currently only handles ac, xf, noise and stb So, going back to the shooting method and removing the reactance from the port element, PSS give the proper and expected result. All we are saying is the reactance is not truly ignored as it should be. Cheers, Kris


    Originally posted in cdnusers.org by kdonate
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