Re: [SI-LIST] : w element

Mike Degerstrom (degerstrom.michael@mayo.edu)
Wed, 21 Jul 1999 08:32:44 -0500

Scott,

As I posted several days earlier - make sure you play with
the ".option risetime=xx" parameter. We were a beta test
site for the w-element model a couple of years ago. The
transient model only gives an approximation to the real lossy
line response. However, for most applications, I contend that
you are far better off using the w-element than any of the other
HSPICE transmission line models. Also the w-element model
is extremely efficient when simulating large numbers of coupled
conductors.

Mike

On Jul 20, 10:46pm, Scott McMorrow wrote:
> Subject: Re: [SI-LIST] : w element
> It will be interesting to see where this thread leads. We are currently
> performing some very basic simulation tests with w-elements and
> are discovering some extremely unsettling behavior.
>
> scott
>
> SiQual
>
> Larry Smith wrote:
>
> > Tanmoy - did you see the discussion on SI list pertaining to w element?
> > Look under the thread: even-odd mode influence.
> >
> > Larry
> >
> > > From: "John Williamson" <williamj@nortelnetworks.com>
> > > To: "'si-list@silab.eng.sun.com'" <si-list@silab.eng.sun.com>
> > > Subject: RE: [SI-LIST] : even-odd mode influence
> > > Date: Fri, 16 Jul 1999 08:57:05 -0500
> > > MIME-Version: 1.0
> > > X-Orig: <williamj@americasm01.nt.com>
> > >
> > > Folks,
> > >
> > > A comment on HSPICE lossy coupled T-line accuracy. Be careful when using
the
> > > W-element.
> > > We've found that the time and frequency domains do not agree. For
example, a
> > > set of extracted
> > > RLGC parameters resulted in a frequency domain attenuation of -25dB at
> > > 10GHz. However when
> > > the same model was used in the time domain driven by a 10GHz sine wave,
the
> > > attenuation was
> > > only -8dB. We've found that this can be corrected by dividing the model
up
> > > into several shorter
> > > ones. It's not computationally efficient, but it works fairly well.
> > >
> > > Regards,
> > >
> > > jw
> > >
> > > John M. Williamson, 0V30, Electromagnetic & interconnect technology
> > > Nortel Networks
> > > (613) 763 3198, ESN 393-3198 E-mail: williamj@nortel.ca
> > >
> > > > -----Original Message-----
> > > > From: jaydiep@us.ibm.com [SMTP:jaydiep@us.ibm.com]
> > > > Sent: Thursday, July 15, 1999 4:49 PM
> > > > To: si-list@silab.eng.sun.com
> > > > Subject: [SI-LIST] : even-odd mode influence
> > > >
> > > >
> > > >
> > > > Weber,
> > > >
> > > > To be able to simulate even-odd mode effects, you'll have to model the
> > > > conductors as a system of coupled transmission lines. There are not
many
> > > > simulators that can do it, and even the ones that can are pretty
limited
> > > > to the
> > > > number of conductors they can handle. Many of them can only handle
lumped
> > > > models, where what you really need to see what's going on is a true
> > > > distributed
> > > > model. You'll need a field solver to extract the coupled transmission
> > > > line
> > > > matrices - it's not easily done analytically. Take a look at Ansoft,
> > > > Applied
> > > > Simulation Technology, and Pacific Numerix. HSPICE can model coupled
> > > > lines
> > > > using geometric input (conductor size, spacing, etc.), but I can't
vouch
> > > > for its
> > > > accuracy.
> > > >
> > > > Jay Diepenbrock
> > > >
> > > > Senior Engineer
> > > > Interconnect Technology & Qualification
> > > > IBM Global Procurement, B8UA/061, RTP, NC
> > > > Phone: 919-543-8804 Fax: 919-543-3642
> > > > Email: jaydiep@us.ibm.com
> > > >
> > > >
> > > >
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>-- End of excerpt from Scott McMorrow

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