Re: [SI-LIST] : IBIS models at Gbit speeds

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From: Ron Miller ([email protected])
Date: Fri Dec 10 1999 - 11:26:13 PST

Hi Brad

I am using HP ADS a frequency domain simulator with Impulse, a real time convolution
to the time domain with time domain models mixed in. I started using this because of the
problem with spice not modeling frequency dependent losses properly for some cable losses.

The ADS simulations matched the measured results very nicely. However, the problem
with ADS is that the simulations take a long time to run when converting back to the time
domain, so they are a bit slow and expecially when having large spice circuits driving and
receiving the signals.

My question is, does the W element simulations closely match the measured results of
 cable and long PCB traces?

Thanks

Ron Miller

Bradley S Henson wrote:

> Let me further propose we discuss the overall reliability of all of our tools
> and techniques for gigabit digital. Like many of you, I found out the hard way
> that the old HSPICE models (prior to "W" elements) could be very wrong at
> microwave frequencies. Consequently, I think we all need to question, and
> discuss, the efficacy of our present SI tools and techniques. We need to all be
> thinking about including frequency dependent dielectric as well as conductor
> losses. SI tools that use lossless approximations break at these rates, etc.
> Could make for some fun since many of us are already out on the edge dealing
> with multiboard bit rates in the GHz range. Hey, even the dreaded trace
> corner-mitering topic has a completely new context for 2GHz digital rates ;) For
> the sake of the list, we'll leave that one lay...
>
> Brad Henson, Engineering Fellow
> Raytheon Systems Co.
>
> "zanella, fabrizio" <[email protected]> on 12/08/99 01:21:45 PM
>
> Please respond to [email protected]
>
>
>
>
>
>
>
> To: "'SIList'" <[email protected]>
>
> cc: (bcc: Bradley S Henson/RWS/Raytheon/US)
>
>
>
> Subject: [SI-LIST] : IBIS models at Gbit speeds
>
>
> > Hello SI engineers,
> > Does anyone have experience using IBIS models to simulate serial
> signals at
> > frequencies of 1GHz and above? I have an IBIS model for a SERDES
> device,
> > and I'm concerned about its behavior and accuracy at these
> frequencies.
>
> > Thanks and regards,
> Fabrizio Zanella
> Hardware Engineering
> EMC Corporation
> 508-435-2075, x14645
> FAX: 508-497-8027
> [email protected]
>
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--
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017
     ==========0000-(_)0000===========
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
[email protected],  [email protected]

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