RE: [SI-LIST] : Frequency dependence and all that jazz

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From: Jian Zheng (jian@zeland.com)
Date: Wed Dec 22 1999 - 18:37:02 PST


Hi, Ron:

You can also try our MDSPICE simulator which basically accept the SPICE
netlist (limited to R, L, C, K) and s-parameter files compatible with the HP
measurement results in files. We also offer accurate and efficient full wave
simulators. Thanks!

Best regards,
----------------------------------------------------------------------------
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Jian-X. Zheng, Ph.D
Zeland Software, Inc., 39676 Mission Blvd., Fremont, CA 94539, U.S.A.
Tel: 510-797-8109, Fax: 510-797-8241, Web: http://www.zeland.com
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    -----Original Message-----
    From: owner-si-list@silab.eng.sun.com
[mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Ron Miller
    Sent: Wednesday, December 22, 1999 4:23 PM
    To: si-list@silab.eng.sun.com
    Subject: Re: [SI-LIST] : Frequency dependence and all that jazz

    Nilesh
    Please contact Art Frasier at Intel, Santa Clara. He has HP MDS/ADS
which
    can used measured S-parameters together with other frequency dependent
elements
    and transfer them back into the time domain.

    Ron Miller

    Steve Corey wrote:

        Nilesh -- SPICE-like simulators doing time-domain analyses solve
their differential equations in the time domain, based on the charge/flux
stored in
        capacitors/inductors and the derivatives of the voltage/current
variables at each node/branch. A time-domain simulator has no concept of
frequency.
        It is quite possible to get frequency dependence included in a model
for a time-domain simulator, since L's and C's are frequency-dependent
        impedances/admittances and can be shown, when used in conjunction
with R's (and inductance coupling coeffficients) to accurately represent any
well-behaved
        function if used in the correct topology and with the correct
values. However, for certain structures (e.g., long cables used at high
frequencies) a large
        number of lumped elements is required to represent the delay.

        A full wave solver is one of many approaches to getting a frequency
dependent model. Other approaches, such as 2-D solvers, may be quite
sufficient
        without going to such great lengths -- you have to evaluate what
frequency-dependent effects you are trying to model. /* begin brazen
advertising */ We
        offer a tool which extracts models from measured data and handles
some effects, such as non-uniform impedance and next-door coupling, quite
well. /* end
        brazen advertising */ General full-wave modeling from measurement is
on the horizon, and is a current research topic in academia, but we do not
offer it at
        this time.

        Hope this helps,

          -- Steve

        -------------------------------------------
        Steven D. Corey, Ph.D.
        Time Domain Analysis Systems, Inc.
        "The Interconnect Modeling Company."
        http://www.tdasystems.com

        email: steve@tdasystems.com
        phone/fax: (206) 417-3439
        -------------------------------------------

        "Shah, Nilesh N" wrote:

> Hi:
> I have a question:
> It's all well and fine to build frequency dependent MODELS,
> but what about the simulator(ex Hspice) itself?
> For example, if I feed the output of a simple inverter to an
> L,C, R network, (and I'm doing a simple time domain transient
analysis)
>
> INVERTER------LRC NETWORK----OUTPUT
>
> does the simulator decompose the output waveform of the inverter
> into it's frequency components before feeding it into the LC
network?(i
> don't think so)
> For example, if the output of my buffer looks like a repeating
square pulse
> running at 400Mhz 50% duty cycle with a finite rise time, does the
LRC
> network "see"
> the input wave as
> Asin(w1t)+Bsin(w2t)+..... etc
> where w1=400Mhz and w2,w3 etc are the harmonics?Or does one have
to
> explicitly
> take the output of the waveform, decompose it and then feed it
artificially
> to the LRC network?
>
> or does the LRC network "see" as it's input,a bunch of dc points
for
> which the simulator solves the nodal matrix using difference or
differential
> equations? i.e. does the LRC network "see" only 1 frequency coming
in which
> is the fundamental?
>
> How does this work?How is the frequency content of the output
waveform of
> the buffer conveyed to the LCR network?
> I was planning to investigate this but I thought some of
> you experts out there might have the answer at the top of your
head...
>
> Also, tools like Ansoft Q3d extract models only at 1 frequency(I
think), so
> unless you use HFSS, how do you get a true frequency dependent
model?
> I've generated R,L versus frequency and other parameter versus
frequency
> curves, but this is with 2 d models using TEM assumptions.what
about 3-d
> models?
> is ther ANY way at all except for using a full wave solver like
HFSS to
> generate true frequency
> dependent models and simulate in the time domain?
>
> Thanks for your ideas in advance.
> Nilesh
>
>
> Nilesh N Shah,
> Package Electrical Design Engineer,
> PCG, Folsom, CA.
> Intel Corporation.
> tel:916-356 1129.
>
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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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