FreeLists / si-list / [SI-LIST] Re: HSPICE W element field solver model

["GARY ROSEN" <gmr@xxxxxxxxxx>]

Isn't one of the problems with FR-4 repeatability, i. e. the properties
(such as dielectric and loss tangent) are not consistent from batch
to batch or manufacturer to manufacturer?  This is aside from
(or in addition to) the fact that these properties may be less
favorable for high-speed design.

- Gary Rosen

mmunroe wrote:

> Dear Alex,
>
> I take exception to Mike's comment "Fire the consultant."  I certainly
> don't know all the details and I don't suggest that a data rate of 3
> Gigabits/second is easy to execute, within standard FR-4.  However there
> are consultants who have accomplished 3 Gigabits/second on FR-4 for more
> than a couple of projects. The signaling technology, the distances to be
> traversed, proximity to noise sources and other design requirements will be
> the factors which together will ultimately determine the feasibility of
> your effort.  However, I would not presume to say that 3 Gigabits/second on
> FR-4 is an unreasonable design goal today.
>
> Several connector manufacturer's, ERNI included, have published system
> simulations demonstrating equally data rates over significant distances
> through two connector interfaces.  Actual system demonstrations have been
> performed also demonstrating these data rates.  That is exactly why
> differential connectors and fabless IP semiconductor companies like Velio
> Communications are putting such an emphasis in this application area.  It
> is just that what was nearly impossible 24 months ago is becoming eminently
> practical now.
>
> michael munroe
> The ERNI Group
> 804-530-4283
> mmunroe@xxxxxxxxx
>
> -------------Forwarded Message-----------------
> From:   INTERNET:si-list@xxxxxxxxxxxxx, INTERNET:si-list@xxxxxxxxxxxxx
> To:     "'si-list@xxxxxxxxxxxxx'", INTERNET:si-list@xxxxxxxxxxxxx
> Date:   6/8/101 10:55 PM
> RE:     [SI-LIST] Re: HSPICE W element field solver model
>
> Fire the consultatnt.
>
> Mike.
>
> -----Original Message-----
> From: Alex Horvath [mailto:alexh@xxxxxxxxxxxxxxxx]
> Sent: Friday, June 08, 2001 1:31 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: HSPICE W element field solver model
>
> Chris,
> I found your statements below very interesting because we have a consultant
> working for us that's telling us 3 gig on a FR-4 backplane (20") is no big
> deal. I told him I had some concerns based on the chip manufacturers data
> which recommended GETEK or similar. Do any simulators take losses into
> account?
>
> Are there any publications or papers that discuss in more detail the DK and
> loss tan you mentioned below? This is the first time I have worked at
> frequencies where this is a concern.
>
> Thanks,  Alex H
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Mesibov
> Sent: Friday, June 08, 2001 4:58 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: HSPICE W element field solver model
>
> Most PCB fabricators and their lamenate suppliers don't characterize FR4
> above 1.5 GHz (i.e. for DK and loss tan).  Therefore specifying controlled
> impedance lines intended for this bandwidth should be rejected by any fab
> house worth
> their salt. The problem is that the studies of FR4 at frequencies up to
> 10Ghz show
> dramatic changes in loss tan and DK over freq and temp.  What this would
> result in
> for digital signals is group delay and rise time degradation.  Group delay
> is
> when the fourier components of the waveform propagate down the transmission
> line
> at different rates.  The rise time degrades because as the frequency
> increases,
> so does the loss tangent.  This has the effect of attenuating the harmonics
> of
> the waveform, thus slowing the rise time.
>
> Hope this sheds some light.
>
> Chris
>
> Alex March wrote:
>
> >   Dear SI experts,
> >
> >   I would like to ask about your experiences with the
> > W element field solver model in HSPICE. I am trying to
> > make some simulations in the Gigahertz range with FR4
> > material and I am not sure about what value I should
> > use for the conductivity of FR4.
> >
> > Thank you,
> >
> > Alex
> > __________________________________________________
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> --
>  Chris Mesibov
>  Sr. Hardware Engineer Fujitsu Network Communications, Inc.
>  Phone:(845)731-2037   2 Blue Hill Plaza, 6th Floor
>  Fax:  (845)731-2011   Pearl River, NY 10965
>
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