At present there are at least 2 commercial tools that that I am aware of thatstate they enforce passivity in the models they generate. Those tools are: Sigrity's BroadBand Spice (latest version), EMWonders's EMtoSPICE. There are several other companies providing tools to generate spice models via the rational approximation approach from measured or simulated S and/or Y parameters, but I'm not aware that they have implemented passivity enforcement.. I'm sure someone will chime in if there other tools that enforce passivity that I'm not aware of. If you haven't examined the work of Dr. Gustavsen at SINTEF, I suggest you visit his Vector Fitting web site at http://www.energy.sintef.no/Produkt/VECTFIT/index.asp . You will find his papers and further info on vector fitting in general and passivity enforcement in particular including downloadable Matlab code which implements those concepts. In addition to the commercial tools available you may want to check out the work done at Georgia Tech by Dr. Swaminathan and his students on a tool called BEMP. The tool enforces passivity and is extensively discussed in several of the papers they have published. Most of the passivity enforcment work that I am aware of deals with the problem of S-parameters at DC by extrapolating the s-parameter data from the lowest frequency data points available down to DC if a value at DC is not provided in the data set. Deng, Zhichao wrote: >I am a PhD student and I am doing literature research on the topic of >rational approximation with passivity enforcement. > >It seems that the passivity enforcement are almost based on the state >space form with LMI or Hamiltonian matrices for the passivity of either >Y or S parameters. > >1) Is there any commercial tool available has passivity enforcement >capability? > >2) What is the latest trend on passivity enforcement? > >3) How to fix DC value of S parameter during vector fitting process? > >Thank you. > > > ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu