**From:** Leo Yuan (*[email protected]*)

**Date:** Tue Nov 28 2000 - 16:10:12 PST

**Next message:**Ray Anderson: "Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Previous message:**Haller, Robert: "RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Maybe in reply to:**Ray Anderson: "FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Next in thread:**Ray Anderson: "Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"

Hi Ray,

Can you add Robert Wu and Albert Chen to the alias?

Thanks

-Leo

*> From: Chung-hsiao Wu <[email protected]>
*

*> Subject: Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

lines

*> To: [email protected]
*

*> Cc: [email protected]
*

*> MIME-Version: 1.0
*

*> Content-MD5: 83bzSSE5JTegVKSpa43Kew==
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*>
*

*> No, I'm not. Can someone add me ?
*

*>
*

*> Thanks,
*

*> -Robert
*

*>
*

*> > Date: Tue, 28 Nov 2000 15:44:21 -0800 (PST)
*

*> > From: Leo Yuan <[email protected]>
*

*> > Subject: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

*> lines
*

*> > To: [email protected], [email protected], [email protected]
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*> > Cc: [email protected], [email protected]
*

*> > MIME-Version: 1.0
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*> > Content-MD5: jbQ+X/xamIzhPie9spGjxA==
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*> >
*

*> > Are you on this alias?
*

*> >
*

*> >
*

*> > ------------- Begin Forwarded Message -------------
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*> >
*

*> > From: Ray Anderson <[email protected]>
*

*> > Subject: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

*> lines
*

*> > To: [email protected], [email protected]
*

*> > MIME-Version: 1.0
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*> > Content-MD5: ruLZY1y3nu7A/k6+l3ffvA==
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*> >
*

*> >
*

*> > Recently there has been an ongoing discussion on si-list
*

*> > regarding the accuracy of the Hspice W element. I am forwarding
*

*> > the most recent message posted by Avanti's developer currently in
*

*> charge
*

*> > of the W element (the 3rd or 4th guy in the past 3 years) in which
*

*> > he addresses 4 of the open issues known to exist with the W element.
*

*> >
*

*> > -Ray Anderson
*

*> >
*

*> > ECIT SI Group
*

*> >
*

*> >
*

*> >
*

*> > ------------- Begin Forwarded Message -------------
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*> >
*

*> > To: [email protected]
*

*> > Cc: [email protected], [email protected],
*

*> > [email protected]
*

*> > Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

*> lines
*

*> > Mime-Version: 1.0
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*> > Content-Transfer-Encoding: 7bit
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*> > Date: Mon, 27 Nov 2000 17:58:30 -0800
*

*> > From: Ted Mido <[email protected]>
*

*> > X-Dispatcher: imput version 990905(IM130)
*

*> >
*

*> >
*

*> > Dear SIers,
*

*> >
*

*> > I am a developper of hspice and currently taking in charge of
*

*> W-element.
*

*> > You may have seen following information on W element feature from
*

*> > the person who had been taking in charge of W element. But for those
*

*> who
*

*> > haven't read seen it I would like to resend this by adding up to date
*

*> > information. Please take a look at this.
*

*> >
*

*> > ---
*

*> >
*

*> > I would like to clarify the four Hspice issues which have been
*

*> > actively discussed:
*

*> >
*

*> > 1) Accuracy of the field solver for computing the skin-effect
*

*> > matrix Rs.
*

*> > 2) Discussion of the inclusion of the imaginary term for Rs:
*

*> > SQRT(f)*Rs [eq1] vs. SQRT(f)*Rs*(1+j) [eq2].
*

*> > 3) Discrepancy between the transient and ac analysis results for
*

*> > the cases with non-zero Gd values.
*

*> > 4) Discrepancy between the transient analysis results using
*

*> > a single long line versus several short lines.
*

*> >
*

*> > (1) It is clearly stated in the Hspice manual that the computation
*

*> > of Rs does NOT account for any proximity or edge effects; hence,
*

*> > the resulting value is significantly smaller than the actual value.
*

*> > This is consistent with the computed data by Richard Mellitz.
*

*> > We are currently working on implementing a new solver which
*

*> > accurately models the skin, proximity and edge effects.
*

*> > For 2000.4 release, we have implemented a new field solver which
*

*> > is for skin effect resistance and inductance which have following
*

*> > features.
*

*> >
*

*> > Advantage:
*

*> >
*

*> > 1. Effects due to magnetic coupling such as skin effect
*

*> > and proximity effect can be modeled.
*

*> > 2. Resistive ground plane is taken into account (but not in C and
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*> G).
*

*> >
*

*> > Side Effect: (*important*)
*

*> >
*

*> > 1. Rs has off diagonal components due to magnetic coupling
*

*> > 2. Lo becomes bigger than previous extraction because of
*

*> > proximity effect especially under the condition of high
*

*> > resistive ground plane.
*

*> >
*

*> > Limitation:
*

*> >
*

*> > 1. due to the limitation of "RLGC" model input (only real value),
*

*> > imaginary part of Rs is ignored. this may cause error in
*

*> > high frequency R,L value. In fact Rs is computed to fit
*

*> > the formula [eq.2] which models skin effect resistance.
*

*> > (in future release, this will be solved by changing the
*

*> > output to "frequency tabular RLGC model" which is
*

*> > implemented in 2000.4 described below.)
*

*> >
*

*> >
*

*> > (2) The main issue for this second problem is that while including
*

*> > the imaginary term [eq2] models the skin effect (marginally) better
*

*> > at high frequencies, it may introduce a significant error at low
*

*> > frequencies. Some people, especially those working on high
*

*> > frequency applications, are accustomed to use [eq2] while others
*

*> > prefer [eq1].
*

*> >
*

*> > I prefer to use [eq2] since it is mathematically more valid solution
*

*> > at the high frequency range where the SQRT(f) dependency is valid,
*

*> > and furthermore, both equations are not accurate at low frequencies
*

*> > anyway. I ran some test cases using both equations and observed no
*

*> > significant differences in ac analysis. However, the accuracy of
*

*> > the transient analysis is slightly degraded when [eq1] is used.
*

*> >
*

*> > Nonetheless, we will change the implementation so that you can
*

*> > optionally exclude the imaginary term.
*

*> >
*

*> > (The ultimate solution to this Rs problem, as it has been pointed
*

*> > out by Michael Tsuk, could be to use a better modeling equation
*

*> > or even tabular data.)
*

*> >
*

*> > (3) The difference in attenuation between transient and ac analyses
*

*> > with non-zero Gd values is a rather subtle problem. The cause of
*

*> > this problem is mainly due to the limitation of the dielectric
*

*> > model equation based on f*Gd as has been pointed out by Dmitri.
*

*> >
*

*> > (4) The discrepancy between the transient results using a single
*

*> > line versus several cascaded short lines is mainly due to the
*

*> > limitations on the difference approximation routine used in
*

*> > W-element for the frequency-dependent cases. Recently, we have
*

*> > significantly improved the difference approximation routine, and
*

*> > and this discrepancy has been eliminated. (No risetime parameter
*

*> > setting is necessary anymore.)
*

*> >
*

*> >
*

*> > All of these improvements will be available for the next release
*

*> > of Hspice (version 99.4). We will soon make a beta version available
*

*> > (approximately 1 month); however, the new solver mentioned in (1)
*

*> > won't be implemented in this beta version.
*

*> >
*

*> > I hope this note clarifies all the issues related to the W-element
*

*> > and field solver in Hspice.
*

*> > I apologize for a somewhat late response.
*

*> >
*

*> > Regards,
*

*> >
*

*> >
*

*> >
*

*> > : Ted Mido
*

*> > : Avant! Corporation (Oregon R&D)
*

*> > : 9205 SW Gemini Drive
*

*> > : Beaverton, Oregon 97008
*

*> >
*

*> >
*

*> > From: David Kaiser <[email protected]>
*

*> > Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

*> lines
*

*> > Date: Mon, 27 Nov 2000 17:28:12 -0700
*

*> >
*

*> > > Nope. This is conjecture based on my expectations and experience. But
*

*> > > when I confronted a support person at Avanti, he addmitted that there
*

*> > > may be limitations above 1GHz.
*

*> > >
*

*> > > David
*

*> > >
*

*> > > -----Original Message-----
*

*> > > From: Larry Miller [mailto:[email protected]]
*

*> > > Sent: Monday, November 27, 2000 11:53 AM
*

*> > > To: David Kaiser; Kai Keskinen; [email protected]
*

*> > > Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
*

*> lines
*

*> > >
*

*> > >
*

*> > >
*

*> > > Yes, but have you compared your results (either) with real hardware?
*

*> > >
*

*> > > Inquiring minds want to know....
*

*> > >
*

*> > > Thanks,
*

*> > >
*

*> > > Larry Miller
*

*> > >
*

*> > > -----Original Message-----
*

*> > > From: David Kaiser [SMTP:[email protected]]
*

*> > > Sent: Monday, November 27, 2000 10:17 AM
*

*> > > To: Keskinen, Kai [KAN:0G15:EXCH]; [email protected]
*

*> > > Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element
*

*> > > transmission lines
*

*> > >
*

*> > > I have compared the W-element with the RLGC matrix from running
*

*> > > APSIM on 100 Ohm diff'l pairs). With a 30ps pulse and 10ps rise
*

*> times,
*

*> > > the reflected pulse was very symetrical for the W-element, but showed
*

*> > > and RC roll off with APSIM. The APSIM seemed to shown a more
*

*> realistic
*

*> > > reflection pulse.
*

*> > >
*

*> > >
*

*> > > David Kaiser
*

*> > > McDATA Corp.
*

*> > > 310 Interlocken Pkwy.
*

*> > > Broomfield, CO 80021
*

*> > > (303) 460-4431
*

*> > > [email protected]
*

*> > >
*

*> > >
*

*> > >
*

*> > > -----Original Message-----
*

*> > > From: Kai Keskinen [ mailto:[email protected]
*

*> > > <mailto:[email protected]> ]
*

*> > > Sent: Thursday, November 23, 2000 11:19 AM
*

*> > > To: [email protected]
*

*> > > Subject: [SI-LIST] : Accuracy of HSPICE W-element transmission lines
*

*> > >
*

*> > >
*

*> > >
*

*> > > Hello SI-People:
*

*> > >
*

*> > > We have now several times encountered differences in results
*

*> > > from other modelling packages and results from HSPICE w-element
*

*> models
*

*> > > for applications involving fairly long striplines > 30cm on FR4 and
*

*> > > GETEK with 2.5Gbps signals with ~100ps edge rates. The W-element
*

*> model
*

*> > > appears to give lower loss than the other techniques. Typical track
*

*> > > widths are 6-8 mils with 100Ohm loosely coupled differential pairs.
*

*> > >
*

*> > > Avant! claims the W-element method is accurate without providing
*

*> > > a paper showing how it was validated.
*

*> > >
*

*> > > How does the rest of the SI community feel about the accuracy of
*

*> > > the W-element model?
*

*> > >
*

*> > > Thanks in advance,
*

*> > >
*

*> > > Kai Keskinen
*

*> > > Equipment and Network Interconnect
*

*> > > Nortel Subsystems and Performance Networks (NSPaN)
*

*> > > (613)-765-3506 (ESN 395)
*

*> > > [email protected]
*

*> > >
*

*> > >
*

*> >
*

*> > **** To unsubscribe from si-list or si-list-digest: send e-mail to
*

*> > [email protected] In the BODY of message put: UNSUBSCRIBE
*

*> > si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
*

*> > si-list archives are accessible at http://www.qsl.net/wb6tpu
*

*> > ****
*

*> >
*

*> >
*

*> > ------------- End Forwarded Message -------------
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*> >
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*> >
*

*> >
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*> > ------------- End Forwarded Message -------------
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*> >
*

*> >
*

*> > #######################
*

*> > Leo Yuan
*

*> >
*

*> > Phone:(650) 786-6110
*

*> > Fax: (650) 568-9603
*

*> > #######################
*

*> >
*

*>
*

#######################

Leo Yuan

Phone:(650) 786-6110

Fax: (650) 568-9603

#######################

**Next message:**Ray Anderson: "Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Previous message:**Haller, Robert: "RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Maybe in reply to:**Ray Anderson: "FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"**Next in thread:**Ray Anderson: "Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines"

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