Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission lines

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From: Leo Yuan (Leo.Yuan@eng.sun.com)
Date: Tue Nov 28 2000 - 16:10:12 PST


Hi Ray,

 Can you add Robert Wu and Albert Chen to the alias?
 
 Thanks
 
 -Leo
> From: Chung-hsiao Wu <chwu@ha1mpk-mail>
> Subject: Re: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
lines
> To: yuan@ha1mpk-mail
> Cc: chwu@eng
> MIME-Version: 1.0
> Content-MD5: 83bzSSE5JTegVKSpa43Kew==
>
> No, I'm not. Can someone add me ?
>
> Thanks,
> -Robert
>
> > Date: Tue, 28 Nov 2000 15:44:21 -0800 (PST)
> > From: Leo Yuan <yuan@ha1mpk-mail>
> > Subject: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
> lines
> > To: chwu@ha1mpk-mail, albert.chen@ha1mpk-mail, bao.ngo@ha1mpk-mail
> > Cc: jjong@ha1mpk-mail, ansu@ha1mpk-mail
> > MIME-Version: 1.0
> > Content-MD5: jbQ+X/xamIzhPie9spGjxA==
> >
> > Are you on this alias?
> >
> >
> > ------------- Begin Forwarded Message -------------
> >
> > From: Ray Anderson <Raymond.Anderson@eng.sun.com>
> > Subject: FWD: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
> lines
> > To: hspice-interest@sun.com, wgs-spice@east.sun.com
> > MIME-Version: 1.0
> > Content-MD5: ruLZY1y3nu7A/k6+l3ffvA==
> >
> >
> > 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 -------------
> >
> > To: david.kaiser@mcdata.com
> > Cc: ldmiller@nortelnetworks.com, keskinen@nortelnetworks.com,
> > si-list@silab.eng.sun.com
> > Subject: RE: [SI-LIST] : Accuracy of HSPICE W-element transmission
> lines
> > Mime-Version: 1.0
> > Content-Transfer-Encoding: 7bit
> > Date: Mon, 27 Nov 2000 17:58:30 -0800
> > From: Ted Mido <mido@avanticorp.com>
> > 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
> 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 <david.kaiser@mcdata.com>
> > 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:ldmiller@nortelnetworks.com]
> > > Sent: Monday, November 27, 2000 11:53 AM
> > > To: David Kaiser; Kai Keskinen; si-list@silab.eng.sun.com
> > > 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:david.kaiser@mcdata.com]
> > > Sent: Monday, November 27, 2000 10:17 AM
> > > To: Keskinen, Kai [KAN:0G15:EXCH]; si-list@silab.eng.sun.com
> > > 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
> > > davidk@mcdata.com
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Kai Keskinen [ mailto:keskinen@nortelnetworks.com
> > > <mailto:keskinen@nortelnetworks.com> ]
> > > Sent: Thursday, November 23, 2000 11:19 AM
> > > To: si-list@silab.eng.sun.com
> > > 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)
> > > keskinen@nortelnetworks.com
> > >
> > >
> >
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> >
> >
> > ------------- End Forwarded Message -------------
> >
> >
> >
> > ------------- End Forwarded Message -------------
> >
> >
> > #######################
> > Leo Yuan
> >
> > Phone:(650) 786-6110
> > Fax: (650) 568-9603
> > #######################
> >
>

#######################
Leo Yuan

Phone:(650) 786-6110
Fax: (650) 568-9603
#######################


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