## [SI-LIST] Re: Need your Opinion and expertise

• From: "Xilei Liu" <xileil@xxxxxxxxxxx>
• To: ariazi@xxxxxxxxxxxx
• Date: Wed, 19 Jul 2006 21:21:30 +0000

```Abe,

I have to clarify that Pade' approximation is not a new method from the
popular approches you stated. If you have commercial simulators or field
solvers that can extract RGLC from S-parameters available, just use it. Many
simulators employ Pade' approximation method to implement the extraction. If
you want to extract RGLC from S-parameters or voltage/current by yourself,
you may refer to "R. Nakhla and R. Achar. Model-Reduction
Algorithms(Principles, AWE, CFH and Macromodeling)"

If you work out Z, Y matrice or z, y from S-parameters or V/I, then use a
Pade' approximation routine that deals with complex numbers to get a
relationship f(s)=b0+b1(s)+b2(s^2)+.../1+a1(s)+a2(s)+..., where s=jw. If the
order of s is small (1 or 2), then it's possible for you to work out a
simple circuit model by hand, otherwise you will need a micromodel. Any way
you still need to evaluate the stability.

Many field solvers obtain RGLC from Z, Y matrice with N dimension, and for a
commercial software, they run 3D mesh to do many other things you don't
really need. If you do this by yourself, it can be faster than running a
full field solver but more accurate than the analytical method.

Regards,
Celine

>From: "Abe (Abbas) Riazi" <ariazi@xxxxxxxxxxxx>
>To: "Xilei Liu" <xileil@xxxxxxxxxxx>
>CC: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: Need your Opinion and expertise
>Date: Wed, 19 Jul 2006 11:30:49 -0700
>
>=20
>=20
> >A basic way is to use Pade'=20
> >approximation to extract RLC and incorporate them into most available
>circuit simulators.
>
>Dear Celine,
>
>There are several effective approaches for RLC modeling of interconnect
>elements. =20
>One popular way is using a TDR in conjunction with IConnect software.
>There also exist mathematical formulae for ascertaining "approximate"
>RLC
>models for a via, connector, PCB trace, etc. Field solvers can be
>applied
>to extract models which are more accurate than by analytical techniques.
>
>Can you furnish a good reference related to use of Pade' approximation
>for RLC modeling
>of IC packages, vias, or connectors?
>
>
>Abe
>
>
>  =20
>
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