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" <zanella_fabrizio@emc.com> on 12/08/99 01:21:45 PM

Please respond to si-list@silab.eng.sun.com
 
 
 
 
 
 

 To:      "'SIList'" <si-list@silab.eng.sun.com>

 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
fzanella@emc.com

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-- 
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017                 
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