Subject: Minutes of 4/1 Meeting

From: "Hobbs, Will" <[email-masked]>
Date: Wed, 06 Apr 94 13:30:31 PST

Date:    April 6, 1994

From:    Will Hobbs (503) 696-4369, fax (503) 696-4210
         [email-masked]
         XTG Modeling Manager, Intel Corp., Chairperson, IBIS Open Forum
         Intel Corporation
         5200 NE Elam Young Pkwy, Hillsboro, Oregon 97124 USA
         and
         Derrick Duehren (503) 696-4299, fax (503) 696-4904
         Intel Program Manager

Subject: Minutes from IBIS Open Forum 4/1/94

To:
Anacad                        Steffen Rochel
Ansoft                        Henri Maramis
Atmel Corporation             Dan Terry
Cadence Design                Sandeep Khanna, Chris Reed,
                              Pawel Chadzynski, Kumar*
Contec                        Maah Sango*, Clark Cochran
Digital Equipment Corp.       Barry Katz*
High Design Technology        Michael Smith
HyperLynx                     Steve Kaufer, Kellee Crisafulli*
IBM                           Jay Diepenbrock
IBM-Motorola alliance         Lynn Warriner, Hoa Quoc, John Burnett
Integrity Engineering         Greg Doyle, Wayne Olhoft
Intel Corporation             Stephen Peters*, Don Telian, Will Hobbs*
                              Arpad Muranyi*, D. Duehren, Lisa Huang*
Interconnectix, Inc.          Bob Ross*
Intergraph                    Ian Dodd*, David Wiens
IntuSoft                      Charles Hymowitz
Logic Modeling Corp.          Randy Harr
Mentor Graphics               Greg Seltzer, Ravender Goyal
Meta-Software                 Mei Wong, Mei-Ling Wei
MicroSim                      Arthur Wong, Jerry Brown, Graham Bell
National Semiconductor        Syed Huq
North Carolina State U.       Paul Franzon, Michael Steer, Steve Lipa
Performance Signal Integrity  Vivek Raghawan, Eric Bracken*
Quad Design                   Jon Powell*
Quantic Labs                  Mike Ventham, Zhen Mu
Racal-Redac                   John Berrie
Siemens Nixdorf               Werner Rissiek, Olaf Rethmeier
Texas Instruments             Bob Ward
Thomson-CSF/SCTF              Jean Lebrun
Zeelan Technology             Hiro Moriyasu, George Opsahl

CC:
Intel Corporation             Randy Wilhelm, Jerry Budelman,
                              Intel IBIS team

In the list above, attendees at the 4/1/94 meeting are indicated by *

Upcoming Meetings: The room and bridge numbers for future IBIS 
teleconferences are listed below:
                     Date       Bridge Number   Reservation #
                    4/15/94    (415) 904-8944,  721615
                    4/29/94    (415) 904-8944,  721618
                    5/13/94    (415) 904-8944,  721619
                    5/20/94    Face-to-face, editing committee

All meetings are 8:00 AM to 10:00 AM PST (16:00 to 18:00 UTC).  We try 
to have agendas out 7 days before each open forum and meeting minutes 
out within 7 days after.  When you call into the meeting, ask for the 
IBIS Open Forum and give the bridge operator the reservation number.

PLEASE NOTE:  Because of the current large number of open issues, we 
decided at the 4/1 meeting to hold meetings on a bi-weekly basis until 
ratification of IBIS 2.0 is achieved.

If you know of someone new who wants to join the e-mail reflector 
([email-masked]) send e-mail to [email-masked].

------------------------------------------------------------------------

4/1/94 Meeting Agenda
----------------------

Check-in
Intros of new IBIS participants                 Hobbs
Review of 3/11/94 minutes                       Hobbs
Miscellany/Announcements                        Hobbs
Opens for new issues                            All
Press updates                                   Hobbs/All
New Models Available                            All
IBIS 2.0 Ratification                           Hobbs
-  DAC Conference 6/6 - 6/10
-  Editing Committee
IBIS Cookbook                                   Hobbs
Spice-to-IBIS Converter                         Lipa (NCSU)
Sign of Current checking                        Chrisafulli, All
BIRD 8, Spec. of V/I data monotonicity          Crisafulli
BIRD 9, Other model types                       Ross
BIRD 10, Coupling Effects in Package Models     Bracken
BIRD 2, VIH, VIL Thresholds for Inputs          Powell
Egg 1, mutual pin coupling (ready to hatch?)    Bracken
Simulation temperatures (new BIRD?)             Warriner
Ramp measurement                                Reid, Ross, et. al.
Egg 2, ramp table?                              Hobbs
Canright paper                                  Ward
Formal BNF notation (BIRD?)                     Reed, Harr
High freq. and EMI                              Goyal, et. al.
Phased turn-on/off of multiple devices          Powell
Wrap-up, Next Meeting Plans                     Hobbs

1.  Intros of new IBIS participants
New participants: None.  In fact, due to the meeting taking place on 
Good Friday, attendance was 30% lower than normal.

2.  Review of 3/11 Minutes
There were no corrections made to last month's minutes.

3.  Miscellany/Announcements
No new announcements.

4.  Opens for new issues
Jon Powell has questions regarding a new model developed by Intel for 
the Neptune 3.3v PCMC chip set which exhibits non-monotonic behavior 
with the pulldown when the voltage goes below ground.  Kellee also has a 
customer that is using it and agrees that this is a probable problem.  
We agreed to discuss this issue later in the meeting.

Kellee would also like to defer discussion of Bird 8 to a future meeting 
in favor of the new BIRD 11, IBIS_CHK checks for table sign.

5.  Press updates
There is an article on IBIS about to come out in EDA and ASIC magazine 
and the March issue of Computer Design, on page 38, devotes a couple of 
paragraphs to IBIS.

6.  New Model Availability
New models:  Intel's 486DX4 model is about to go on BBS.  Expect it in 
about a week.  Arpad also has some new models that are ready for 
posting.

AR, Stephen, Arpad, get models up on the vhdl.org BBS.

7.  IBIS 2.0 Ratification: DAC Meeting, Editing Committee
Jon Powell proposed the meeting take place on Sunday, from 1-6, with 
Monday as an overflow day.  Jon could provide facilities that day.  
Various members preferred not to meet on Sunday and Kumar offered for 
Cadence to provide a room on any day, and needs the number of 
participants.  We tentatively set the meeting for 8-5 on Thursday, 6/9.

AR Will, send out notice, ask for RSVPs, for 6/9, 8-5. -- Done

Will suggested we convene an IBIS Birds of a Feather session to be held 
through DAC.  Bob Ward said that to do this only requires that 10 people 
express interest and DAC will supply a time and a room.  Bob was 
volunteered to follow through on this.

AR, Bob Ward, get Birds of a Feather session on DAC agenda.  Launch note 
to reflector to get at least 10 replies from those interested in 
attending. -- Done

Regarding the 5/20 editing get-together in Oregon, it was suggested we 
divide up tasks into controversial/non-controversial topics and quickly 
close on the non-controversial ones and tackle the remainder separately.  
Possibly work in sub-groups.

8.  IBIS Cookbook
Intel has completed its first revision of the internal IBIS Modeling 
Cookbook, and has made its first pass at a "sanitized" version for use 
by the forum.  Will solicited volunteers to help get this in shape for 
the forum, and the following individuals stepped forward: Jon Powell, 
Bob Ross, Kellee Chrisafulli, Maah Saango, Barrie Katz, Arpad Muranyi, 
Kumar and Eric Bracken.

AR Will, organize the review and editing effort for the cookbook. -- WIP

9.  Spice to IBIS
Bob Ross has used sp2ibis with Pspice and provided some feedback to 
Steve.  Bob found some differences between Pspice results and Berkeley 
Spice, gave Steve that feedback and another iteration is underway.  Bob 
judges the program usable, but more work is required.  Barrie at DEC has 
it and will be using it soon.

Jon Powell:  How will it be used?  If it is to be used primarily by IC 
vendors, it does not have to be as clean; if its target is customers, it 
must be cleaner. Kellee: IC vendors are #1, because they will have the 
greatest impact.  Bob Ross: But it will be public domain, so anyone can 
use it.  Jon is concerned if there is a minor bug that might create 
major glitch, a model review would be required, so modeling and buffer 
expertise would be required to be successful, or the evaluation of 
Sp2ibis will have to be greater.  Kellee:  maybe we should ask Steve to 
add something in the program's output to indicate need to correlate 
resulting model against the original design (a disclaimer or caveat).

There was a short discussion about what to do about released IBIS models 
that had erroneous behavior.  Is there a way to resolve such issues?  
Jon suggested that models should contain the originator's name, or some 
way to get a message back to originator.

AR Jon, organize thoughts, post to reflector.

10.  New Issue: Non-Monotonic Pull-Down Behavior
Re: pulldown on Neptune, Arpad on line.  Jon feels the pulldown 
transistor becomes linear, and doesn't believe the curve.  Arpad had 
dissected the design and checked the devices and verified the behavior 
as reflected in the model.

AR Arpad, write up a discussion of this for the reflector.

Jon:  if you are right, all the other IBIS models are wrong.  Kellee: 
The question is whether in the negative region is the diode carrying the 
current or is the pulldown?  Arpad:  The models have not always been 
correlated in that region.  Earlier models are still useful, because 
they are still more accurate in the forward biased diode regions than 
many other spice models that are out there.  Arpad would like to 
continue this discussion in a forum where we can draw pictures, and 
would like to add this discussion to the cookbook.

Jon:  Quad does not model non-monotonic parts.  The model that Arpad is 
generating will not work in Quad tools.  Arpad questions whether Jon can 
use the data together-- the transistor is non-monotonic, but the diode 
and the diode/transistor combination do not.

Maah:  we're confusing 2 issues-- what does the data look like, and how 
do we model it?

ARs, Arpad, post description of his findings that led him to the new 
model data.  Specify one particular model for everyone to look at.  
psc_a2.ibs

11.  BIRD 11, IBIS_CHK Changes
Kellee Crisafulli proposes three changes in this BIRD, each related to 
the sign of VI table data, which has proven to be a common pitfall among 
new modelers.  First, the BIRD proposes adding a comment to the IBIS 
specification discussing the sign of VI table data; second, add checking 
to ibis_chk for the correct sign, using the algorithm tuned through 
reflector feedback; and third, add a note to the ibis_chk source saying 
a BIRD is required to change the source.

Proposed changes 1 and 3 appear OK to group, with the additional comment 
that source licensees are free to modify their own source, but not to 
post the result.  Only the ibis_chk czar (Jon Powell) can post modified 
versions of ibis_chk, and that requires a ratified BIRD to initiate.

Regarding change 2, there is controversy about the sign of the ECL 
example.  Kellee pulled the example out of the IBIS V1.1 spec, which was 
a CMOS example, and indicated that if this was an ECL example then there 
would be a sign error because for ECL pulldown, VI is Vcc-V per BIRD 4.

Kellee feels that right thing to do is to change the sign and use ECL 
type data and present a correct ECL table, but doesn't have ECL data.  
Kumar has ECL data which he offered to supply for inclusion in the BIRD.

AR Kumar, post ECL model to reflector, Kellee, use that data in the 
BIRD.

AR Kellee, change the proposed ibis_chk notice to indicate that it is OK 
to change your own source code, but not the global one without a 
supporting BIRD.

12.  Wrap-up
Because we ran out of time, and because a number of people did not 
attend due to the meeting taking place on Good Friday, we decided to 
convene on a bi-weekly basis until DAC so we could get 2.0 in shape.  
Thus, next meeting will be on Bad Friday, 4/15.  (For those non-U.S. 
citizens reading this, April 15 is when Americans must pay their taxes.)

AR Will-- make meeting bi-weekly until DAC, post new bridge numbers. -- 
Done.  Dates and numbers appear on the first page of these minutes.