Subject: IBIS User Group Minutes - June 25, 1998 meeting

From: Kathy Breda <[email-masked]>
Date: Thu, 09 Jul 1998 12:06:57 -0400

***Minutes of the IBIS Users Group Meeting

   held at Stratus on Thursday, June 25, 1998***

NEXT Meeting:

	Date:  Thursday, August 20, 1998

	Time:	 3:00 PM

	Place: Stratus, Marlboro, MA

Thanks to Bruce Heilbrunn of Stratus for hosting the

June meeting.  We are in the process of setting up

 a conference phone link for those who are interested

 in calling into the meetings.  Details to follow.

We are taking the month of July off and will get

back together in late August.

We plan on hosting an IBIS Summit during PCB-East

in mid October (15th)  and also providing an IBIS two hour tutorial

at that time as well.   We'd be very interested

in hearing feedback on the type of IBIS information

you would be interested in learning about.  The summit will be held in

the Marlborough Massachusetts area - Stratus has

indicated interest in letting us use their beautiful, new

amphitheater for the meeting. 

Agenda of June 25th meeting:

*  IBIS education curriculum

*  Update on Connector Modeling BIRD

*  Accuracy Specification and Test Board Update

Education:

Ed Sayre and Joe Socha are working up an education curriculum.  

We would like to use it for the IBIS tutorial at the

IBIS Summit in October.

<bold><underline>IBIS Accuracy Sub-Committee

</underline></bold>

The IBIS Accuracy specification is moving along well.  

The Sub-Committee has been meeting regularly to discuss the

specification and has been focusing on the required measurements

and the measurement techniques.

The subcommittee has decided to specify which measurements to make on 

a given I/O buffer, but not which buffers to measure on a given IC.

There are three measurement categories, IV curves, Test load waveforms,

and capacitance (frequency and time domain).  The capacitance
measurement

is the most difficult to make due to fixturing.

Regarding measurement techniques for IV Curves, sweep far enough to turn
on

the clamp diodes when they exist.  Sweep farther if no diodes exist, but 

do not exceed absolute maximum current, as cooking the parts is not
good!

Compute the cable IR drop and use a 4-point probe or another cable if

the voltage is big enough relative to your swing.  Team decided that 

the specification should include a drawing and description on how to 

use the 4-point probe.

<bold><underline>Connector Models Sub-Committee

</underline></bold>

Two members have been added to the group:  Mark Gailus and Michael
Khusid, Teradyne

Kellee Crisafulli, of HyperLynx reported the Connector Models
Sub-committee progress 

at the IBIS summit meeting at DAC.  Since he has had experience writing
IBIS BIRDs

Kellee will be writing the Connector Model BIRD.

The Sub-committee has 1 hr conference calls every other week.

The following items have been agreed to by the Connector Sub-Committee:

	<bold>*</bold>The model will have several L, C sections connected in
series

	<bold>*</bold>The matrices in each section will be the same size

	<bold>*</bold>They are adding a value defining maximum bandwidth of the
connector.

	Connector vendors will define the minimum slew rate that the connector

	is useable.  The software will flag users - if any driver on the
network

	going through the connector has a slew rate below minimum, then the
user

	will be flagged.

	<bold>*</bold>The model can be created from 2D, 3D solvers or
measurements

	<bold>*</bold>The group is discussing whether to include sliding
matrices - smaller

	 matrices that can be re-used across the board.  <bold>looking for
input!

</bold>	<bold>*</bold>The model will consist of Tline model sections,
similar to wline model

 	 from HSPICE where you define ground on each end of the connector

	<bold>*</bold>The model will support fixed return path in the connector
(shield) and

	 defining n+1 node as return within the model.  If it is just pins,

	 it will pick a pin(s) plane.