[SI-LIST] Re: Simple Rational Model Estimation Method Given Transfer Function
- From: Charlie Sweet <csweet@xxxxxxxxxxxxxxx>
- To: shlepnev@xxxxxxxxxxxxx
- Date: Wed, 7 Apr 2010 11:36:40 -0400
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
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On
> Behalf Of eenville
> Sent: Wednesday, March 31, 2010 11:31 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Simple Rational Model Estimation Method Given Transfer
> Function
>
> Any suggestions appreciated on simple, preferably open-source, tools to
> develop a good (e.g., in a least-squares sense for both real and imaginary
> components) low order rational model (i.e., pole/zero) given magnitude and
> phase of a transfer function vs. frequency? The phase info is relatively
> smooth but the roll-off and passband do not look like a second or even 3rd
> order model would suffice.
>
> Any ideas appreciated!
>
> Thanks,
>
> Charlie
>
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--
- Charlie
----
Charlie Sweet | Principal Engineer
Sunrise Labs | 5 Dartmouth Drive | Auburn | NH | 03032
Tel: 603-644-4500 | Fax: 603-622-9797 |
csweet@xxxxxxxxxxxxxxx | http://www.sunriselabs.com
New Product Development "from mind to market"
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