[SI-LIST] Re: Simple Rational Model Estimation Method Given Transfer

From: "Dmitriev-Zdorov, Vladimir" <vladimir_dmitriev-zdorov@xxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Date: Thu, 8 Apr 2010 09:44:53 -0600

Charlie,

Think of your transfer function as 1-port (1x1) S-parameter matrix. Find
poles/residues, then implement it as a transfer function (i.e. Laplace
or Pole E-element).

Vladimir

On Wed, 7 Apr 2010 11:36:40 -0400
Charlie Sweet wrote:

Hi Yuriy,
Thanks for your feedback, I looked into the vectfit Matlab / Octave
script
and found it focuses on fits to Y or S parameter matrices.
I am interested in pole-zero fits to a transfer function, not full 2
port Y
or S parameter matrices.
Can I assume S11=S22=0 and S12=S21 with magnitude of S21 = transfer
function
gain and phase of S21 = transfer function phase to obtain a reasonable
pole-zero fit or is more required to obtain a causal, stable model?  The
transfer functions typically are smooth functions with no
discontinuities in
magnitude or phase versus frequency.  The actual networks are not
passive
and I am primarily interested in the forward direction, not reflections.

Thanks,

Charlie

On Wed, Mar 31, 2010 at 2:52 PM, Yuriy Shlepnev
<shlepnev@xxxxxxxxxxxxx>wrote:

> Charlie,
>
> VECTFIT is the software for rational macro-modeling developed by Bjorn
> Gustavsen - available at
> http://www.energy.sintef.no/Produkt/VECTFIT/downloads.htm
> Pretty much all fitting or rational macro-modeling tools in the
industry
> are
> based on the vectfit algorithm (though the performance and
capabilities are
> very different in each implementation).
>
> Our free tool Simbeor 2008.01 L0 can be also used to build rational
> macro-models for 2-port structures (available at
> www.simberian.com/Downloads.php - item 2, the download requires
> registration
> at our web site).
>
>
> Best regards,
> Yuriy Shlepnev
> www.simberian.com
>
>

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[SI-LIST] Re: Simple Rational Model Estimation Method Given Transfer

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