Re: [SI-LIST] : w element

Scott McMorrow ([email protected])
Tue, 20 Jul 1999 22:46:21 -0700

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" <[email protected]>
> > To: "'[email protected]'" <[email protected]>
> > Subject: RE: [SI-LIST] : even-odd mode influence
> > Date: Fri, 16 Jul 1999 08:57:05 -0500
> > MIME-Version: 1.0
> > X-Orig: <[email protected]>
> >
> > 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: [email protected]
> >
> > > -----Original Message-----
> > > From: [email protected] [SMTP:[email protected]]
> > > Sent: Thursday, July 15, 1999 4:49 PM
> > > To: [email protected]
> > > 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: [email protected]
> > >
> > >
> > >
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