[SI-LIST] Re: rational function approximation
- From: Ray Anderson <Raymond.Anderson@xxxxxxx>
- To: bhadhua@xxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Thu, 15 Apr 2004 16:26:09 -0700
Amitava-
Question: Did you extrapolate your s-parameter data down to DC (or
otherwise define the s-parameters at zero frequency)? I have been told
that when creating rational function approximations from s-parameters
that the s-parameter behavior at DC can effect the passivity of the
resultant model. Did you go through the eigenvalue drill to prove or
disprove passivity or does Spectre check it for you?
Does Spectre actually do a rational function approximation internally
with Laplace type elements or is it creating a model using a frequency
response table ?
I'm not familiar with the nport element in Spectre. Do you know if it
is it similar to the Hspice s-element ?
Maybe some of the modeling gurus from the CAD tool companies will
respond with a better answer.
-Ray Anderson
Sun Microsystems Inc.
Amitava Bhaduri wrote:
>
> Hi,
>
> Using a full-wave tool I have been able to generate an impedance matrix of
> an N-port interconnect and later converted the Z matrix into S-parameters.
> Using "nport" from spectre I tried connecting the generated parametric
> data to the remaining device netlist of the circuit. But the simulation
> doesn't work due to stability and passivity problem. I have generated the
> impedance data for 10 frquency points.
> I have learnt that using rational function approximation the passivity of
> the network can be ensured, but I am not sure how to proceed with that
> with Z-matrix (or S-matrix) in hand. Can anyone suggest ways or the
> necessary steps that I have to folow in order to make the interconnect
> network passive and use it with spectre circuit simulator. Is it possible
> to use MATLAB to do this rational function approximation and if it is,
> then how do I do it?
>
> Thanks in advance,
> Amitava
>
> Amitava Bhaduri
> Research Assistant
> 527 ERC
> University of Cincinnati
> OH - 45220
> ph(lab) : 513-556-3025
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