Subject: Re[2]: Connector spec swathing

From: [email-masked]
Date: Wed, 14 Jun 2000 10:09:11 -0500

An important point in using a "swath".

The initial swath matrix MUST be large enough (i.e. represent enough pins) such
that the appropriate number of coupling effects can be observed.

That being said... the swath was created to make a single large "matrix" out of
a smaller "matrix".  The goal being to automatically create a banded matrix.

The swath really wasn't created to DIRECTLY pick a pin (or multiple random pins)
out of a connector for simulations.  (Although it might be possible, I just
haven;'t thought it through).

Would it be easier if the original matrix (assuming it is initially wide enough)
is swathed to represent a banded  matrix first ? 

Basically, using the small matrix, incorporating matrix symmetry, and
disregarding a given number of coupling effects to create a banded matrix.

The then resultant banded matrix would be a part of the simulation deck  (not
the original small matrix)

Am I way out on this one?

_gus: 630-527-4617

Also, for what it is worth...  for this example, I would suggest that the
starting PIN matrix would be at least 3 x 9.

____________________Reply Separator____________________
Subject:    Re: Connector spec swathing
Author: Mike LaBonte <[email-masked]>
Date:       6/14/00 10:38 AM

I would like to add an illustration of Chris Reid's point, as I see it.
Here is an ASCII picture of a connector. The pins marked as 'X'
are those carrying the signals that the simulation product has
determined MUST be characterized and simulated. The '0' pins are
the other pins of the connector:

0 0 0 0 0 X O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 0 0 0 0 X 0 0 0 0 0 0 0 X 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 X 0 0 0 0 0 0

Assume that the connector model uses a 3x3 swath with 1 left edge
and 1 right edge (5x3 total matrix size). Here is one possible
pattern for using the swath, where 'M' represents matrix middle pins,
and 'E' represents pins in an edge column, which must be terminated
by Cn_Z. The '?' pins are those that could be either an edge or a
middle, depending on which nearby swath it is considered to be "in":

0 0 E M M X E 0 0 0 E M M ? ? M M E 0 0 0 0
 0 0 E M X M E 0 0 0 E M X ? ? M M E 0 0 0 
0 0 E M M M E 0 0 0 E M M ? ? X M E 0 0 0 0

There is no single swath that can contain the 2 pins on the right.
But 2 swaths, each centered around one pin, will overlap. Most likely
the simulator will have to make some choice that does not fulfill the
intent of the model developer. Even the 2 pins on the left have some
ambiguity; I chose the pin in the middle row as my center point, but
the choice is not always obvious.

On the subject of centering a swath around a pin, a swath with an even
number of columns has four possible locations, giving four possible
simulation results, depending on which is chosen. This is because the
swath has no pin at the center, but has 4 pins equally close to the center.

Since simulators have to handle a full matrix anyway, I would have to
join Chris Rokusek in hoping for a solution that turns a connector model
into a full matrix.

Mike LaBonte
Cadence
<SNIPPED to save BW>

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From: chris <[email-masked]>
Date: Wed, 14 Jun 2000 09:13:20 -0700

Mike,

Thanks for your illustration of my point.  Clearly we have
exactly the same concern.

Gus,

Yes, including the larger matrix that is supposed to be expandable
to a full banded matrix would be useful, but it should also include
instructions on just how that smaller matrix is supposed to be used
to get the full banded matrix.

Thanks,

Chris