RE: [IBIS] Package model question

-----Original Message-----
> Hello everyone,

> I wonder what the intent was for the matrix syntax of the
> package descriptions in the IBIS specification.

> In the non-matrix syntax we described in great detail that
> if the Len parameter is zero, the simulator tool supposed
> to build a lumped circuit using the LRC parameters, and
> when it is non-zero it should use distributed T-lines.

> I can't find anything similar when we describe the matrix
> format, yet it seems that the RLC matrix parameters could
> still be used in a lumped or distributed fashion.  I mean,
> just because these are matrixes, it doesn't mean that they
> must automatically be distributed T-lines...  (Or does it?)

> Can anyone clarify this to me?  Does anyone remember what
> the intent was?

> Thanks,

> Arpad
===========================================================

Arpad-

I can't speak to the intent of the spec writers when the matrix format
for package data was specified, however the use of the matrix data is
generally dependent on the transmission line models implemented by the
simulator developers.

The RLC data specified in the matrix can be used to specify W-element
type distributed models, or the data can be distributed across a
multi-section lumped RLC transmission line model. I would suspect that
no simulator uses the RLC values to just specify a single lumped t-line
as the bandwidth would be too small to be useful.

There doesn't appear to be a need to specify the use in the IBIS model
as it is really up to the implementers of the simulator.

-Ray

Raymond Anderson
Senior Signal Integrity Staff Engineer
Product Technology Department
Advanced Package R&D
Xilinx Inc.



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