IBIS Macromodel Task Group

Meeting date: 02 May 2017

Members (asterisk for those attending):
ANSYS:                        Dan Dvorscak
                            * Curtis Clark
Broadcom (Avago):             Xingdong Dai
                            * Bob Miller
Cadence Design Systems:       Ambrish Varma
                              Brad Brim
                              Kumar Keshavan
                            * Ken Willis
eASIC:                      * David Banas
                              Marc Kowalski
Ericsson:                     Anders Ekholm
GlobalFoundries:              Steve Parker
IBM                           Luis Armenta
                              Trevor Timpane
Intel:                      * Michael Mirmak
Keysight Technologies:      * Fangyi Rao
                            * Radek Biernacki
                              Ming Yan
Maxim Integrated Products:    Hassan Rafat
Mentor, A Siemens Business:   John Angulo
                            * Arpad Muranyi
Micron Technology:          * Randy Wolff
                              Justin Butterfield
QLogic Corp.:                 James Zhou
                              Andy Joy
SiSoft:                     * Walter Katz
                              Todd Westerhoff
                            * Mike LaBonte
Synopsys:                     Rita Horner
                              Kevin Li
Teraspeed Consulting Group:   Scott McMorrow
Teraspeed Labs:             * Bob Ross
TI:                           Alfred Chong


The meeting was led by Arpad Muranyi.

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Opens:

- None.

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Review of ARs:

- Radek to send BIRD 158.5 to Mike L. for posting by Friday April 28th.
  - Done.

- Walter to send BIRD 166.2 to Mike L. for posting.
  - Done.

Bob Ross and Walter to create a BIRD 186.3 draft 2.
  - Done.  It is actively being discussed in the Editorial Task Group meetings.

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Call for patent disclosure:

- None.

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Review of Meeting Minutes:

- Arpad: Does anyone have any comments or corrections? [none]
- Mike L.: Motion to approve the minutes.
- Michael M.: Second.
- Arpad: Anyone opposed? [none]

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New Discussion:


BIRD 166.2 Redriver Flow:
- Discussion: Arpad noted that he thought we had finished with this topic at the
  previous meeting.  His recollection was that Walter was to create BIRD 166.2,
  which essentially rolled back the changes introduced in BIRD 166.1 and went
  back to the original BIRD 166.  This could then be considered for inclusion
  into IBIS 7.0, and the new advanced proposal for additional IR outputs from
  the Tx and Rx could be added later.  Curtis and Walter agreed with Arpad's
  summary of events, and Curtis noted that he had captured events this way in
  the previous week's minutes.  Arpad, however, then noted that an email sent by
  Fangyi the morning of today's meeting had expressed concerns with BIRD 166.2.

  Fangyi noted that BIRD 166.2 reverted to BIRD 166, which was three years old.
  He noted that discussions when BIRD 166 was first introduced had come to the
  conclusion that it was limited.  It relied on deconvolution in certain cases
  and this could be problematic. 

  Walter noted that the basic redriver flow involved 4 devices (Tx1, Rx1, Tx2,
  Rx2).  If all four of their models were Init() only, the flow in IBIS 6.1 was
  wrong, and the flow in BIRD 166.2 was right.  Similarly, if all 4 devices'
  models were dual-mode (functional Init() and GetWave()), then the flow in IBIS
  6.1 was wrong, and the flow in BIRD 166.2 was right.  Walter noted that there
  were 81 possible flow combinations for a two channel redriver flow (4 devices,  
  each with 3 possible model types: Init() only, GetWave() only, dual).  Walter
  noted that IBIS 6.1 flows had problems (relied on convolution) even for some
  of the 9 flow combinations for a single Tx to Rx channel.

  Arpad again noted that he wanted to make sure we took an incremental approach
  in which any change we introduced would not have to be undone later.  Radek
  noted that Walter's proposal was a partial improvement that was okay for many
  situations, but that we might have to abandon it later in favor of the final
  corrections.  Walter disagreed and said that his approach was independent of
  adding the new IRs.  He said that until the new IRs were added, one couldn't
  even start to worry about the special cases for which BIRD 166.2 had issues.
  Bob R. expressed concern about maintaining backward compatibility, and asked
  if a 7.0 model would not work in a later 7.1 flow.  Walter said it would work
  fine because a 7.0 model would not advertise that it supported the additional
  IRs.  Arpad said that while he liked some of the improvements in the advanced
  proposal from Fangyi, he had heard from Vladimir that it would take
  significant time for tool developers to implement the proposal.  Therefore,
  he preferred the incremental approach (introducing BIRD 166.2 first) if
  possible.

  Fangyi said any proposed improvement should not be limited to only half the
  cases.  Mike L. asked if BIRD 166.2 would make it harder for Fangyi to
  implement the advanced proposal.  Fangyi said that the proposals went in
  different directions.  Walter disagreed and said that for the basic cases his
  BIRD was correcting, the flow and IRs would be exactly the same in the two
  proposals.

  Walter motioned for a straw poll on whether the attendees would want ATM to
  recommend to the Open Forum that BIRD 166.2 be included in IBIS 7.0
  (note: not a motion to make that recommendation, just a straw poll
  on where attendees stood on the subject).  Bob Miller seconded.  The results
  by member organization:

     ANSYS:     yes
     Broadcom:  abstain
     Cadence:   abstain
     Intel:     abstain
     Keysight:  no
     Mentor:    yes
     Micron:    abstain
     SiSoft:    yes
     Teraspeed: abstain

  Yes(3), No(1), Abstain(5)

  Those abstaining were interested in more information on the differences
  between the proposals or Fangyi's objections to BIRD 166.2.  Arpad and Michael
  Mirmak asked if Fangyi or Walter could present a side by side comparison of
  proposed flows.  Arpad mentioned slides 14 and 16 of this DesignCon
  presentation (http://www.ibis.org/summits/feb17/katz.pdf) as an example.  Bob
  M. said that he wanted the BIRD 166.2 change introduced quickly, but he also
  wanted the advanced proposal.  He noted that understanding exactly why Fangyi
  thought BIRD 166.2 would get in the way was important.  Arpad, Bob M., and
  Walter asked Fangyi if he could demonstrate specific examples in which BIRD
  166.2 would impede future progress.

- Mike L.: Motion to adjourn.
- Michael M.: Second. 
- Arpad: Thank you all for joining.

AR: Walter and Fangyi to prepare information for the continued discussion of 
    BIRD 166.2 and any effect it would have on future improvements.

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Next meeting: 09 May 2017 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives
