# Re: [SI-LIST] : Incorporating 3-d passive circuit models into SPICE

Fred Balistreri (*fred@apsimtech.com*)

*Fri, 24 Apr 1998 15:56:04 -0700*

Mike Degerstrom wrote:

*> *

*> The recent post by Julia and the response from Dmitri (I've included*

*> the messages below) are very closely related to a modeling capability*

*> that I've been seeking.*

*> *

*> Most specifically, we are able to take both s-parameter TDR*

*> measurements of structures such as vias, connectors, packages*

*> and so on to determine the electrical characteristics for these structures.*

*> We next want to extract from those measurements a suitable model*

*> with which to perform a transient simulation.*

*> *

*> Now one could certainly develop an equivalent circuit representation*

*> composed of passive elements (R, L, and C) for the structure, then*

*> simulate to compare to the measured data to validate the model. But*

*> in practice this becomes more difficult - especially as applications*

*> begin to require multi-Ghz clock rates.*

*> *

*> Therefore, I am wondering if anyone has taken frequency measurements*

*> such as s-parameters and found a reliable method to approximate the*

*> poles and zeros? If so, do you use the Laplace approach mentioned by*

*> Dmitri to incorporate the model into a transient circuit simulation?*

*> *

*> Mike*

*> *

*> On Apr 23, 4:23pm, Dmitri Kuznetsov wrote:*

*> > Subject: Re: [SI-LIST] : Ferrite Beads in HSPICE*

*> > Julia Nekrylova wrote:*

*> > >*

*> > > Hi,*

*> > >*

*> > > Does anybody know the easy way to incorporate ferrite beads*

*> > > (frequency-dependent resistors/inductors) into HSPICE*

*> > > transient analysis?*

*> > >*

*> > > Thanks*

*> > >*

*> > > Julia Nekrylova*

*> > > N.E.T.*

*> >*

*> >*

*> > Hi Julia,*

*> >*

*> > You can implement frequency-dependent resistors and inductors in Hspice*

*> > using frequency-dependent controlled current or voltage sources, the*

*> > LAPLACE function in G or E elements. It lets you specify the frequency*

*> > dependence in a pole-zero form or as a frequency table. The pole-zero*

*> > form is simulated faster and more accurately.*

*> >*

*> > There is also magnetic core model for L elements (inductors). That one*

*> > accounts not only for the frequency dependence but also for the*

*> > nonlinear hysteresis effects in ferromagnetics.*

*> >*

*> > Dmitri*

*> >*

*> > =======================================================*

*> > Dmitri Kuznetsov, Ph.D.*

*> > R&D Engineer, Hspice Group*

*> > Avant! Corporation*

*> > e-mail: vdm@avanticorp.com*

*> > =======================================================*

*> >-- End of excerpt from Dmitri Kuznetsov*

*> *

*> --*

*> _______________________________________________________________*

*> Mike Degerstrom Email: degerstrom.michael@mayo.edu*

*> Mayo Clinic - Gugg. Bldg. RM 1011-B Phone: (507) 284-3292*

*> Rochester, MN 55905 FAX: (507) 284-9171*

*> WWW: http://www.mayo.edu/sppdg/sppdg_home_page.html*

*> _______________________________________________________________*

We do the same approach as Hspice using Laplace transfer functions. We

have a tool that reads in the S parameters, does a curve fit and then

automactically makes the Laplace transfer functions for you that run

in Spice.

Best Regards,

--
Fred Balistreri
fred@apsimtech.com
http://www.apsimtech.com