Subject: Re: pspice problem
Date: Sat, 28 Dec 2002 00:08:20 +0100
Organization: Worldonline Belgium
References: <3E0C8548.A5FBAFBC@n.zgs.de> <3E0C8EE4.F5C1362E@ieee.org>
NNTP-Posting-Date: Fri, 27 Dec 2002 23:03:12 +0000 (UTC)
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Kevin Aylward wrote:
> analog wrote:
>>Reiner Goetz wrote in part:
>>>I want to simulate a resistance depending of frequencies Rx=Rx(f).
>>>I can't find any way to do this with spice.
>>Anything that is realizable is generally possible to model in spice.
> However, this particular function is not available in basic
> Spice3/XSpice. I think this is doable in PSpice which has some
> anditional features.
>>Troubles building a model can sometimes be a red flag that the concept
>>for the model is too unrealistic. And if you are not at least
>>attempting to model reality then what's the point?
>>Specifically, what real world device has the characteristic you are
>>trying to model?
>>>I tried it with the current behaviour sources, but "f" as an Input
>>>(variable) is not possible.
>>To construct a non-linear resistor, one can set up a voltage dependent
>>current source as a non-linear function of its own terminal voltage.
>>I've never tried it, but believe a behavioral source's describing
>>function can include frequency. But even if you could, why would you
>>wish to model a non realizable component?
> Its not a non-linear resistor. This is a resistor which varies with
> frequency, and as you note, is not really physically realisable , except
> as an approximation.
> Kevin Aylward
> SuperSpice, a very affordable Mixed-Mode
> Windows Simulator with Schematic Capture,
> Waveform Display, FFT's and Filter Design.
In my opinion every conductor is a frequency dependend resistor. This
phenomenon is also known as skin effect (increasing resistance with