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

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From: Bradley S Henson (bhenson@notes.west.raytheon.com)
Date: Mon Dec 13 1999 - 07:25:21 PST


Hi Ron,

I can only speak to the fact that the frequency dependent parameters are now
included and look substantially more real. I have not stayed put in one job long
enough to actually have my folks characterize this for me! We have some work
going on now, but nothing as well designed as I'd specify. The results will
likely not be sharable due to the funding source :( Again, I don't think anyone
will miss this data much at all since it appears to me to be way too superficial
and poorly designed from an experimental viewpoint.

If I get a chance to compare 'W' elements to measured data I'll share with the
list anything publishable. Unfortunately, I have nothing in the works right
now...

Brad Henson

Ron Miller <rmiller@Brocade.COM> on 12/10/99 11:26:13 AM

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

                                                              
                                                              
                                                              
 To: si-list@silab.eng.sun.com
                                                              
 cc: (bcc: Bradley S Henson/RWS/Raytheon/US)
                                                              
                                                              
                                                              
 Subject: Re: [SI-LIST] : IBIS models at Gbit speeds
                                                              

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
     ==========0000-(_)0000===========
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net


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