IBIS Macromodel Task Group

Meeting date: 13 October 2015

Members (asterisk for those attending):
ANSYS:                      * Dan Dvorscak
                            * Curtis Clark
Avago (LSI)                   Xingdong Dai
                            * Bob Miller
Cadence Design Systems:       Ambrish Varma
                              Brad Brim
                              Kumar Keshavan
                              Ken Willis
eASIC                         David Banas
                              Marc Kowalski
Ericsson:                     Anders Ekholm
IBM                           Steve Parker
Intel:                        Michael Mirmak
Keysight Technologies:      * Fangyi Rao
                            * Radek Biernacki
Maxim Integrated Products:    Hassan Rafat
Mentor Graphics:            * 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
Teraspeed Consulting Group:   Scott McMorrow
Teraspeed Labs:             * Bob Ross
TI:                           Alfred Chong

(Note: Agilent has changed to Keysight)

The meeting was led by Arpad Muranyi.

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Opens:

- Walter mentioned that he had some new thoughts on the Redriver Init Flow BIRD
  and would be making a motion to untable it, time permitting.

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Call for patent disclosure:

- None.
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Review of ARs:

- Arpad to clean up draft 14 of the Special_Param_Names BIRD and send it to
  Mike L. for posting to the ATM website.
  - Done (Mike posted it, and Arpad sent an announcement to the ATM reflector).

-------------------------
Review of Meeting Minutes:

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

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New Discussion:
  
Item #6: renamed: New IBIS-AMI Reserved Parameter Special_Param_Names.
- Discussion:  Arpad reviewed draft 14 and highlighted the changes incorporated
  based on last week's meeting.  Radek expressed concern over the wording of
  the long sentence describing the Usage Rules.  After some discussion, all
  agreed that the phrase "in which this parameter appears" could be removed from
  the sentence.  Bob M. then reminded the group of a suggestion he had made that
  the BIRD might state that an EDA tool should throw a warning if it does not
  recognize any of the special parameters in the table.  He felt this was a way
  to ensure that an end user would know of the issue, which was the primary
  benefit a model maker would derive from using the new Special_Param_Names.
  David Banas and others had agreed with Bob M.'s suggestion (first made via
  email).  Attendees understood the value of Bob M.'s proposal, but Arpad and
  Bob R. pointed out that the specification generally avoids defining
  "what the tool should do."  They both stated that it was really a tool vendor
  issue, and the benefit in the BIRD was that it provided a path for model
  makers to declare their special parameters so the tools could do something
  with that information.  Todd said the benefit to the model makers was the fact
  that they could explicitly declare their special parameters.  Bob M. said that
  he had wanted to raise the issue, but was fine with the decision not to define
  what a tool should do with the information.
- Bob R: I move that we submit this BIRD, as modified here today, to the IBIS
         Open Forum with a recommendation from the ATM that they approve it.
- Walter: second.
- Arpad: I think we should take a company by company vote.
  Results of Company Vote:
  ANSYS - yes
  Avago - yes
  Keysight - yes
  Mentor - yes
  Micron - yes
  SiSoft - yes
  Teraspeed Labs - yes
  [unanimous approval]

- Bob R: Submit it to Mike L. to be uploaded as BIRD 179.
  
Item #7: Discussion of language corrections regarding "ground".
- Discussion:  Walter wanted to briefly discuss this topic in anticipation of
  full discussions in future meetings.  He restated that we had all generally
  agreed that "ground" in a buffer referred to a local ground, and that we
  needed to iron out the language of a generic statement of that fact.  He asked
  that Radek take an AR to propose such language.  Radek stated that he had
  completed a smaller AR to offer comments on some of Walter's original slides,
  but that there was some more work to be done to draft a more comprehensive
  description.  Arpad asked if we might start an email thread so we could more
  easily evaluate and comment on any proposed language.  Radek accepted the AR
  to start the email thread aimed at hashing out the ground language.
  
Item #11: New Redriver Flow BIRD.
- Walter: I move that we untable the Redriver Init() Flow BIRD.
- Arpad: Second.
  - Anyone opposed? [none]
- Discussion: Walter reviewed draft 2 of his Redriver Init Flow improvements
  proposal.  Walter reminded everyone that the current spec has a known issue
  with statistical flow for redrivers, and that earlier attempts to alter the
  flow had opened a Pandora's box of issues that he and Fangyi could not resolve
  to their mutual satisfaction.  His new proposal was more limited in scope
  and defined a new Tx_Init_EQ_Depends_On_Input_IR Boolean parameter defined
  for Tx models.  If it was false for a redriver's Tx, as would often be the
  case, that would result in a significantly simplified Init() flow that still
  provided the correct input IR to the downstream Rx.  The proposal detailed
  four distinct methods of combining the effects of both channels for the final
  Rx that would all yield identical results.  If the parameter was true,
  however, the flows get quite involved.  Todd wondered if it made sense to
  have a parameter defined for a Tx model when it was the downstream Rx that was
  the driving requirement.  Walter replied that the Rx was almost always
  initializing its equalization based on the input IR.  It was knowing that
  the Tx did not that allowed for simplifying the flow for this common case.
  Fangyi objected that cross talk was not handled properly by the proposed flow
  even if the Tx did not optimize itself.  He said that to analyze a network
  with crosstalk one needed to have the Impulse Responses handled independently
  for each channel, because crosstalk contributions could be introduced at any
  channel in the chain.  He stated that the flow currently defined in the spec
  properly dealt with this issue by treating each channel independently, but
  he acknowledged that this left the problem with the Redriver Init() flow that
  Walter was attempting to correct.  Fangyi suggested that one possible solution
  that would handle crosstalk was to pass the downstream Rx two different
  impulse responses.  If one were the combined upstream and downstream channel
  IR, and the other were simply the downstream channel's IR, the Init() could
  optimize based on the combined IR and apply those optimized settings to the
  downstream only IR.  Walter stated that he understood what Fangyi was
  proposing and why, but that he felt that his proposal could stand alone and
  offer a separate simplified flow when the parameter is false.  Fangyi said he
  and Walter could continue to discuss the topic.
- Arpad: Now is a good stopping point.
  - Thank you all for joining.

AR: Arpad to submit today's final version of the Special Parameters BIRD to 
    Mike L. to be uploaded as BIRD 179.
    
AR: Radek to start email thread regarding finalizing the language for the
    cleanup of references to "ground".
    
AR: Walter to email draft 2 of the Redriver Init Flow proposal to Mike L. to be
    posted to the ATM website.

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Next meeting: 20 October 2015 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives
