**From:** Ron Miller (*rmiller@Brocade.COM*)

**Date:** Wed Dec 22 1999 - 16:23:24 PST

**Next message:**Shah, Nilesh N: "RE: [SI-LIST] : Frequency dependence and all that jazz"**Previous message:**Steve Corey: "Re: [SI-LIST] : Frequency dependence and all that jazz"**In reply to:**Steve Corey: "Re: [SI-LIST] : Frequency dependence and all that jazz"**Next in thread:**Jian Zheng: "RE: [SI-LIST] : Frequency dependence and all that jazz"**Reply:**Jian Zheng: "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
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*> capacitors/inductors and the derivatives of the voltage/current variables at each node/branch. A time-domain simulator has no concept of frequency.
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*>
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*> 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
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*> impedances/admittances and can be shown, when used in conjunction with R's (and inductance coupling coeffficients) to accurately represent any well-behaved
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*> 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
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*> number of lumped elements is required to represent the delay.
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*>
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*> 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
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*> without going to such great lengths -- you have to evaluate what frequency-dependent effects you are trying to model. /* begin brazen advertising */ We
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*> 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
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*> 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
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*> this time.
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*>
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*> Hope this helps,
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*>
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*> -- Steve
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*>
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*> -------------------------------------------
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*> Steven D. Corey, Ph.D.
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*> Time Domain Analysis Systems, Inc.
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*> "The Interconnect Modeling Company."
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*> http://www.tdasystems.com
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*>
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*> email: steve@tdasystems.com
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*> phone/fax: (206) 417-3439
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*> -------------------------------------------
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*>
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*> "Shah, Nilesh N" wrote:
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*>
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*> > Hi:
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*> > I have a question:
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*> > It's all well and fine to build frequency dependent MODELS,
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*> > but what about the simulator(ex Hspice) itself?
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*> > For example, if I feed the output of a simple inverter to an
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*> > L,C, R network, (and I'm doing a simple time domain transient analysis)
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*> >
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*> > INVERTER------LRC NETWORK----OUTPUT
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*> >
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*> > does the simulator decompose the output waveform of the inverter
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*> > into it's frequency components before feeding it into the LC network?(i
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*> > don't think so)
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*> > For example, if the output of my buffer looks like a repeating square pulse
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*> > running at 400Mhz 50% duty cycle with a finite rise time, does the LRC
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*> > network "see"
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*> > the input wave as
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*> > Asin(w1t)+Bsin(w2t)+..... etc
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*> > where w1=400Mhz and w2,w3 etc are the harmonics?Or does one have to
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*> > explicitly
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*> > take the output of the waveform, decompose it and then feed it artificially
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*> > to the LRC network?
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*> >
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*> > or does the LRC network "see" as it's input,a bunch of dc points for
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*> > which the simulator solves the nodal matrix using difference or differential
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*> > equations? i.e. does the LRC network "see" only 1 frequency coming in which
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*> > is the fundamental?
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*> >
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*> > How does this work?How is the frequency content of the output waveform of
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*> > the buffer conveyed to the LCR network?
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*> > I was planning to investigate this but I thought some of
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*> > you experts out there might have the answer at the top of your head...
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*> >
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*> > Also, tools like Ansoft Q3d extract models only at 1 frequency(I think), so
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*> > unless you use HFSS, how do you get a true frequency dependent model?
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*> > I've generated R,L versus frequency and other parameter versus frequency
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*> > curves, but this is with 2 d models using TEM assumptions.what about 3-d
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*> > models?
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*> > is ther ANY way at all except for using a full wave solver like HFSS to
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*> > generate true frequency
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*> > dependent models and simulate in the time domain?
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*> >
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*> > Thanks for your ideas in advance.
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*> > Nilesh
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*> >
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*> >
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*> > Nilesh N Shah,
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*> > Package Electrical Design Engineer,
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*> > PCG, Folsom, CA.
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*> > Intel Corporation.
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*> > tel:916-356 1129.
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*> >
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*> > **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.
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*> > si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list
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*> > ****
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*>
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*> **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP.
*

*> si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list
*

*> ****
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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**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

**Next message:**Shah, Nilesh N: "RE: [SI-LIST] : Frequency dependence and all that jazz"**Previous message:**Steve Corey: "Re: [SI-LIST] : Frequency dependence and all that jazz"**In reply to:**Steve Corey: "Re: [SI-LIST] : Frequency dependence and all that jazz"**Next in thread:**Jian Zheng: "RE: [SI-LIST] : Frequency dependence and all that jazz"**Reply:**Jian Zheng: "RE: [SI-LIST] : Frequency dependence and all that jazz"

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