Hi Charlie, you may want S12=0 and let S21=Hs. Alan Charlie Sweet <csweet@sunrisela bs.com> To Sent by: shlepnev@xxxxxxxxxxxxx si-list-bounce@fr cc eelists.org si-list@xxxxxxxxxxxxx Subject [SI-LIST] Re: Simple Rational Model 04/07/2010 08:36 Estimation Method Given Transfer AM Function 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 > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > -- - 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" ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu