[SI-LIST] Re: HSPICE W element field solver model

  • From: Larry Miller <ldmiller@xxxxxxxxxxxxxxxxxxxx>
  • To: "'si-list@xxxxxxxxxxxxx'" <si-list@xxxxxxxxxxxxx>
  • Date: Fri, 8 Jun 2001 10:38:21 -0700

The backplane companies like Tyco seem confident about it, and they have
been building back- and mid-planes for telcos for years.

It will be interesting to see where this goes.

Larry Miller

-----Original Message-----
From: Alex Horvath [mailto:alexh@xxxxxxxxxxxxxxxx]
Sent: Friday, June 08, 2001 10:31 AM
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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