Re: S-Parameter to SPICE Model Converter

Rudi ZURBUCHEN (Rudiz@cn.msm.cern.ch)
Thu, 7 Nov 1996 18:35 +0100

Thanks a lot for your information Ray, I'll follow up these leads.

We are still at the beginnings of using SI tools and are currently
using Maxwell SI from Ansoft and HFSS from HP, partly because
these codes are also in use for our accelerator cavity designs.

At the PCB level, we are going to evaluate BoardQuest from
Cadence (Allegro is currently our main PCB layout tool).

I'm not personally using the tools, but my impression is that modelling
interconnects with Maxwell and HFSS is very tedious, may be this
is because we still have to learn a lot.

As a next step, we would like to use an S-parameter to SPICE
converter as a bridge to our analog simulators Saber and PSpice
(our microelectronics group also has a Hspice license).

Best regards,

Rudi Zurbuchen

----------
> From: Ray Anderson
> To: Rudiz
> Cc: si-list
> Subject: Re: S-Parameter to SPICE Model Converter
> Date: Wednesday, November 06, 1996 10:44AM
>
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> Date: Wed, 6 Nov 1996 10:44:01 -0800
> From: raymond.anderson@Eng.Sun.COM (Ray Anderson)
> Message-Id: <199611061844.KAA13685@radium.eng.sun.com>
> To: Rudiz@cn.msm.cern.ch
> Subject: Re: S-Parameter to SPICE Model Converter
> Cc: si-list@silab.Eng
> X-Sun-Charset: US-ASCII
>
> >
> > Hello SI experts,
> >
> > I am looking for a tool capable of converting
> > S-parameter sets into 2G6 SPICE models.
> >
> > Information on availability and practical experience
> > in the context of interconnect modeling would be
> > highly appreciated.
> >
> > Rudi Zurbuchen
>
> There are 2 tools that come to mind. One is ContecSPAR from
> CONTEC (Now Applied Simulation Technology) and the other is part of
> the picosecond modeling option for HP MDS.
>
>
> I've only used the Contec program. It does a Pade' approximation to
> create a 'black box' model subcircuit that is the ratio of two polynomial
> controlled sources. The user has the option of specifying how complex (how
> many terms) to use. The complexity is dictated by how 'well behaved' the
> input s-parameters are and by how wide a bandwidth you want the model to
be
> useful over. You need to watch out for certain cases where you may end up
> with an unstable model due to poles in the RHP, but that is true of the
> Pade'technique in general.
>
> The resulting model always works in Contec Spice but if you use
> the resulting model in Hspice you can run into problems where Hspice's
> ability to handle very small and very large exponents is exceeded. This
> problem is seen when numbers are < 1e-38 and >1e+38 . This problem was
> evident in Hspice 95.2 and as far as I know they haven't fixed it in the
> current release.
>
>
> HP's version ends up creating a lumped element model with user
> selectable topology. I don't remeber the technique that HP is using. I did
> run some sample evaluation problems on both Contec and HP a while back
and
> as I recall the resulting spice simulation results produced by the Contec
> Pade' model and the HP lumped model were very nearly indistinguishable
from
> each other.
>
>
> Ray Anderson
> Sun Microsystems
> Advanced Component Engineering
>
>