[SI-LIST] Re: Rational Approximation with passivity enforcement

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
>2) What is the latest trend on passivity enforcement?
>3) How to fix DC value of S parameter during vector fitting process?
>Thank you.

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