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https://designers-guide.org/forum/YaBB.pl Simulators >> Circuit Simulators >> impedance measurement problem https://designers-guide.org/forum/YaBB.pl?num=1208181777 Message started by Pavel on Apr 14th, 2008, 7:02am |
Title: impedance measurement problem Post by Pavel on Apr 14th, 2008, 7:02am Hello, For my simulation I need to modelize my block as blackbox. In order to measure interface pin impedances, I used Z-parameter measurement technique provided by Eldo (the same thig exists also in Spectre) and based on AC analysis. From this measurement I extracted equivalent schema of my blackbox - R(Vin) and C(Vin) in parallel. Then I did DC analysis of this blackbox. From this analysis I've get also R(Vin). Once compared the results of 2 analysis - AC and DC, I discovered that R(Vin) is different in each case. Where is my error? Thanks in advance. Pavel. |
Title: Re: impedance measurement problem Post by didac on Apr 15th, 2008, 6:57am Hi, Not sure about this one, but how do you know it's an error? I think that you have a frequency dependant impedance, so it's not strange to have a real part different in AC an in DC. Probably the simple R in parallel with C isn't suitable and you need a more complex lumped model to capture the behaviour, or if you are interested only on a limited set of frequency you must calculate the R and C for each frequency and use a different parallel for each sim. Hope it helps, |
Title: Re: impedance measurement problem Post by Pavel on Apr 22nd, 2008, 4:42am Thank you for response, Didac. For my simulation I need equivalent schema for only one frequency. So in my AC simulation setup there was one frequency and Vin was a parameter. If I properly understood you, I can use C(Vin), R(Vin), extracted from AC analysis, for my transistion analysis? And these values (I mean AC-measured C(Vin), R(Vin)) will properly represent my "blackbox"? Thanks. Pavel. |
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