[SI-LIST] Re: Spectre S-parameter based modeling- Stability issues
- From: "Dmitriev-Zdorov, Vladimir" <vladimir_dmitriev-zdorov@xxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Sun, 3 Dec 2006 11:30:35 -0800
Hi Madhu,
We do have a tool that can solve the problem you describe, unless your
original touchstone files are of an extremely bad quality (in terms of
resolution, causality, passivity etc.) For example, if instead of having
L2 norm of the matrix below one, it reaches 1.1...1.5, it is possible to
make the model passive without changing the dependences too much.
However, if the norm goes up to hundreds, this is less likely.
Anyway, we may produce either passive/causal/smooth data in a form of
the touchstone file, re-sampled with sufficient resolution, or, in a
form of an equivalent SPICE-compatible circuit, whichever you prefer.
Please contact off-line for more technical details.
Vladimir
------------------------------
Msg: #5 in digest
Date: Sat, 02 Dec 2006 00:16:01 -0500
From: Madhusudanan K Sampath <mkeezhve@xxxxxx>
Subject: [SI-LIST] Spectre S-parameter based modeling- Stability issues
Hi All,=20
I am using n-port component in spectre to perform time domain simulation
using touchstone s-parameter files for power planes which are obtained
from
measurement/full wave tools. In many cases, the simulation explodes due
to
stability reasons. What are the possible causes of this and how can one
solve this issue. I think Spectre n-port component uses convolution
methods
to perform time domain simulation from frequency domain s-parameter data
and
hence are prone to convergence issues. If so how does it enforce
passivity
in the model. I verified the s-parameter matrix for eigenvalues and it
proves the data is not passive. I would like to compensate for passivity
and
then re-try the time domain simulation. There are quite a few
interesting
passivity enforcements techniques in literature by Dr. B. Gustavsen and
Dr
S.G. Talocia . However they are applied on the rational functions which
are
obtained by vector fitting the data. My question is if I vector fit the
data, enforce the passivity using these techniques and then calculate
the
S-parameter matrix for each frequency point from the passive rational
function model. Will spectre give stable results with this new data ?=20
Please share your ideas and views on this. Thanks in advance.=20
Madhu=20
=20
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