RE: [SI-LIST] : Different IBIS question

tomda (tom_dagostino@mentorg.com)
Mon, 30 Aug 1999 16:46:34 -0700

Doug

We have measured thousands of IC's from most IC manufacturers. I have done
some limited study on these measurements to look at this issue. Though I
cannot vouch for the families you are interested in I have noticed some
encouraging trends in more recent fab technology.

For a given logic family from a given manufacturer buffer consistency has
improved. IV characteristics may have had +/- 50% variations in older
families (ABT, F, etc.) but have smaller (+/-10 to 20%) variations in newer
logic families such as LVT. Transition times may have varied by 3 to one
now look like +/- 50% or so.

This seems to apply to more complex chips such as FPGA's or microprocessors
in a given family as well.

I would not try to extend this between different vendors of the same logic
family. For example TI, National and Philips ABT part have drastically
different IV characteristics.

Tom Dagostino
Mentor Graphics
ICX Modeling Group

-----Original Message-----
From: Doug Brooks [SMTP:doug@eskimo.com]
Sent: Monday, August 30, 1999 2:36 PM
To: si-list@silab.eng.sun.com
Subject: [SI-LIST] : Different IBIS question

There are specific IBIS models for individual part numbers, and then there
are general IBIS models that represent a family of devices made from the
same technology. Presumably, these generic models work as well (or almost
as well) as their specific counterparts.

Has anyone had any experience that would indicate (1) that the generic
models are "pretty close" to their specific counterparts, or (2) that the
generic models can be so different that they can lead you into real trouble
if you use them?

Doug Brooks
.
****************************************************
Doug Brooks, President doug@eskimo.com
UltraCAD Design, Inc. http://www.ultracad.com

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