RE: [SI-LIST] : Proposal: Rs correlation/collaboration for W-Elem ents

Ray Anderson (
Tue, 3 Aug 1999 10:18:17 -0700 (PDT)

A slight clarification on the numbers reported by Apsim RLGC:

The tool calculated Rdc = 1.358E-4 ohms/mil . (That is equivalent to
5.346 ohms/meter).

The numbers I reported were for the frequency dependent resistance (Rs),
that is, the component that is in _addition_ to Rdc .

I assume (but don't know for a fact) that the values calculated are
magnitude values, not just the Real part. I noticed that I labeled
the values as Re(Rs) and that may have been (probably was) an error
on my part.

The tool put out numbers as ohms/mil . I converted to ohms/meter and
divided by sqrt(f) prior to presenting the results. As a sanity check,
here are the raw numbers reported by the tool prior to my manual post

2.777E-4 ohms/mil @ 100MHz
9.857E-4 ohms/mil @ 1GHz
2.372E-3 ohms/mil @ 5GHz


Rich said:
> Ok here's what I did. I ignored your 1MHz. I converted your numbers back to
> Re(rs) and subtracted the DC component, 4.449 ohms/meter. Then I curve fit
> these results back to a sqrt(f) function. The value I then come up with is
> 1.289E-3 Ohms/(sqrt(Hz)*meter). If I multiply by sqrt(2) I get
> Mag(Rs)=1.823E-3 Ohms/(sqrt(Hz)*meter). It looks pretty close to the closed
> from equation to me.
> ... Rich

Ray said:
> I ran Richard's microstrip example under Apsim RLGC 1.500.0
> (a spectral domain solver) and came up with the following
> results:
> Evaluated @ Re(Rs)
> ----------- --------------------------------
> @1MHz 1.4874E-3 Ohms/(sqrt(Hz)*meter)
> @100MHz 1.0933E-3 Ohms/(sqrt(Hz)*meter)
> @1GHz 1.2272E-3 Ohms/(sqrt(Hz)*meter)
> @5GHz 1.3207E-3 Ohms/(sqrt(Hz)*meter)
> The value at 1 MHz is curious in that it is larger than the
> values at higher frequencies which seem to fall on a
> frequency dependent monotonic line.
> Ray Anderson
> Sun Microsystems Inc.

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