Re: [SI-LIST] : Frequency dependence and all that jazz

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From: Arani Sinha (sinha@cauchy.usc.edu)
Date: Wed Jan 26 2000 - 12:02:03 PST


I was going through the old e-mails on this thread and realised
that no one had mentioned frequency independent modeling of frequency
dependent effects.

For example, skin effect can be modeled by dividing the conductor
into filaments. Each filament is a conductor in its own right. The
current distribution in each filament is assumed to be the same. The
circuit representing this conductor is made up of these filaments in
parallel. Now, the filament in the center has maximum mutual inductance
contribution from neighboring filaments in the conductor, and the one
on the surface has lesser. This determines the current through each
filament. This was described in a paper by Weeks et. al in the IBM J.
Res and Dev, 1979.

Frequency independent loop inductance modeling was described in Krauter
& Mehrotra, Design Automation Conference, 1998. This paper has
references
to some earlier papers (Kim & Neikirk, Wheeler).

Regards,

Arani

>
> Nilesh-
>
> The HSPICE W-element can handle limited (but common) frequency dependence of
> just the R and G matrices (not L and C) describing a transmission line. This
> is accounted for in the time domain as well as frequency domain, but it does
> have limitations. Perhaps Dmitri Kuznetsov can comment further.
>
> HP-EEsof's MDS or ADS tools can handle a much wider range of
> frequency-dependent parameters, but while time-domain simulations can be
> performed, they are a bit contrived as the tool was really designed to perform
> frequency domain analysis.
>
> - Erik
>
> On Dec 22, 3:10pm, Shah, Nilesh N wrote:
> > Subject: RE: [SI-LIST] : Frequency dependence and all that jazz
> > Hi:
> > I have a question:
> > It's all well and fine to build frequency dependent MODELS,
> > but what about the simulator(ex Hspice) itself?
> > For example, if I feed the output of a simple inverter to an
> > L,C, R network, (and I'm doing a simple time domain transient analysis)
> >
> > INVERTER------LRC NETWORK----OUTPUT
> >
> > does the simulator decompose the output waveform of the inverter
> > into it's frequency components before feeding it into the LC network?(i
> > don't think so)
> > For example, if the output of my buffer looks like a repeating square pulse
> > running at 400Mhz 50% duty cycle with a finite rise time, does the LRC
> > network "see"
> > the input wave as
> > Asin(w1t)+Bsin(w2t)+..... etc
> > where w1=400Mhz and w2,w3 etc are the harmonics?Or does one have to
> > explicitly
> > take the output of the waveform, decompose it and then feed it artificially
> > to the LRC network?
> >
> > or does the LRC network "see" as it's input,a bunch of dc points for
> > which the simulator solves the nodal matrix using difference or differential
> > equations? i.e. does the LRC network "see" only 1 frequency coming in which
> > is the fundamental?
> >
> > How does this work?How is the frequency content of the output waveform of
> > the buffer conveyed to the LCR network?
> > I was planning to investigate this but I thought some of
> > you experts out there might have the answer at the top of your head...
> >
> > Also, tools like Ansoft Q3d extract models only at 1 frequency(I think), so
> > unless you use HFSS, how do you get a true frequency dependent model?
> > I've generated R,L versus frequency and other parameter versus frequency
> > curves, but this is with 2 d models using TEM assumptions.what about 3-d
> > models?
> > is ther ANY way at all except for using a full wave solver like HFSS to
> > generate true frequency
> > dependent models and simulate in the time domain?
> >
> > Thanks for your ideas in advance.
> > Nilesh
> >
> >
> > Nilesh N Shah,
> > Package Electrical Design Engineer,
> > PCG, Folsom, CA.
> > Intel Corporation.
> > tel:916-356 1129.
> >
> >
> >
> > **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com.
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> > ****
> >
> >-- End of excerpt from Shah, Nilesh N
>
>
>
> --
> ==================================================================
> Erik Daniel, Ph.D. Mayo Foundation
> Voice: (507) 284-1634 Guggenheim 1011B
> Fax: (507) 284-9171 200 First Street SW
> E-mail: daniel.erik@mayo.edu Rochester, MN 55905
> ==================================================================
>
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