Re: [SI-LIST] : Frequency or time domain for componentcharacterization

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From: Aubrey Keith Sparkman (asparky@SparkRight-Solutions.com)
Date: Mon Feb 28 2000 - 18:37:57 PST


Ron,
YOUR "preference" for frequency domain is showing... Either you believe
in FFT our you don't.

There are some situations where frequency domain is more natural such as
narrow band microwave; others where time domain is the easiest to
apply. Ever had any aliasing problems in the time domain? Can you tell
me of any VNA that collects energy both above 10 GHZ and below 10 MHz in
the same measurement. Both frequency and time domain instruments have
their challenges.

Regards,
Aubrey Sparkman

Ron Miller wrote:

> Hi Kai
>
> Im from the microwave origin in SI now.
>
> You cannot get more accurate measurements than from a
> network analyzer measuring the s-parameters.
>
> FFT and convolution are not tricks and have been around for
> many moons.
>
> ADS can be used with an optimization routine to generate values
> for an assumed schematic using curve fitting quite nicely.
>
> Your question should have been "how close to s-parameters can
> a TDR measure? The answer given me by NIST Don Degroot
> in bolder Colorado is that TDNA a time domain program that
> converts a TDR/TDT to s-parameters comes within about .5 db of
> the network analyzer(standard) out to about 10 Ghz.
>
> Ron Miller
>
> Kai Keskinen wrote:
>
>>
>>
>> Hi Folks:
>>
>> I'm in the interconnect group where connectors are our thing. I'm
>> the high speed modeling guy. I take those connector spice models and
>> make sure the connector will work with our drivers/signal
>> paths/receivers. I have a lot of experience with connector models
>> made using TDR measurements. I have recently been sent some models
>> that appear somewhat dubious. The vendor group that made the
>> measurements says they only use a network analyzer and then do the
>> inverse fft and some other tricks to get the time domain. They have
>> some way to fit parameters to a model to get a match to their
>> measurements. My question is, is the frequency domain method as good
>> as using the TDR at various edge rates?
>>
>> Thanks in advance for your comments.
>>
>> Kai Keskinen
>> Equipment and Network Interconnect
>> Nortel Subsystems and Performance Networks (NSPaN)
>> (613)-765-3506 (ESN 395)
>> keskinen@nortelnetworks.com
>>
>
> --
> 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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