IBIS Macromodel Task Group

Meeting date: 09 July 2019

Members (asterisk for those attending):
ANSYS:                        Dan Dvorscak
                              Curtis Clark
Cadence Design Systems:     * Ambrish Varma
                              Ken Willis
Intel:                        Michael Mirmak
Keysight Technologies:      * Fangyi Rao
                              Radek Biernacki
                              Ming Yan
                              Stephen Slater
                              Maziar Farahmand
Mentor, A Siemens Business: * Arpad Muranyi
Micron Technology:          * Randy Wolff
                              Justin Butterfield
SiSoft (Mathworks):           Walter Katz
                            * Mike LaBonte
SPISim:                     * Wei-hsing Huang
Teraspeed Labs:             * Bob Ross

The meeting was led by Arpad Muranyi.  Mike LaBonte took the minutes.

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Opens:

- None

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Review of ARs:
- Ambrish to produce a draft of BIRD197.4 incorporating NRZ_Threshold and DC_Offset clarifications.
  - Done
- Randy to create a new [C Comp Model] BIRD draft incorporating the changes discussed in the meeting.
  - Done.
    

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Call for patent disclosure:

- None.

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Review of Meeting Minutes:

Arpad asked for any comments or corrections to the minutes of the July 2
meeting.  Bob moved to approve the minutes.  Randy seconded the motion. There
were no objections.

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New Discussion:

DDR5 related topics (bin list #11):
Arpad asked if there were comments. Randy said he and Michael Mirmak were
still researching.


Complex C_comp modeling (bin list #6):
Randy showed the draft BIRD.  He said the only change was the insertion of a
sentence to clarify that [C Comp Corner] could be ignored in non-driving mode.
Arpad asked if it was ready for submission. Bob Ross moved to submit the
BIRD to the Open Forum. Randy Wolff seconded. No one opposed, and the motion
carried. Arpad will submit the BIRD.

AR: Arpad Muranyi to submit [C Comp Corner] BIRD to Open Forum


DC_Offset BIRD draft 197.4:
Arpad showed a draft BIRD197.4 and an email from Fangyi Rao.  Ambrish said
BIRD197.4 had been drafted to clarify a few things.  He noted that Fangyi
had responded by email. There was confusion about if and when the model
would change the waveform.  Fangyi asked how the EDA tool would know if the
waveform had been shifted by the model.  Ambrish said the model would provide
a threshold value indicating the amount of shift.  Fangyi said the model
could have both shifted and unshifted waveforms.  He said the language was not
completely clear that it was about the output waveform, not the input waveform.
Arpad said the model could add its own offset even if it did not use the EDA
tool value.  Fangyi asked why we would shift the input waveform.  Ambrish
said it could be either input or output.  Fangyi asked why we would need to
know if it was shifted.  Ambrish said it was to know not to shift it again.
Fangyi said that was mixing two different things, DC offset and NRZ_Threshold
were separate.  He said it was confusing to use the input DC offset to shift
the output.  Ambrish said the model would choose how much it wants to shift,
that it could ignore the DC offset.  Fangyi said the model doesn't shift,
it just processes the waveform.  Arpad said we make the assumption is that
GetWave output always would be centered around NRZ_Threshold, but Fangyi is
saying it may not be.  Ambrish disagreed, feeling that if there were differing
DC offsets we would be doomed.  Arpad said we might have an output that is
not centered around the correct value.  Fangyi asked how a shifted output
could be physical.  Ambrish said the model output waveform can be whatever
it wants.  Fangyi suggested the new sentences were not needed.  He said it
would help if DC_Offset was InOut.  Arpad noted Walter and Fangyi were out on
vacation at times when changes were made.  Ambrish said he would be out the
next few weeks.  Fangyi said the threshold had to apply to the output waveform.

Arpad noted that Walter Katz was the BIRD author, but Walter had indicated
disapproval of some proposed changes.  Maybe a new BIRD should be drafted.
Ambrish asked if fixing the input vs. output waveform ambiguity would help.
Fangyi pointed out the problematic sentence.  Ambrish agreed that "input
waveform" could cause confusion there.  Fangyi asked why the output would
be shifted by the input offset.  Ambrish said the same offset applied at
both ends.  Fangyi asked who had suggested shifting the output waveform.
Randy said it was a way of visualizing the actual waveform.  Fangyi asked
why the model would give the amount of shift.  Ambrish felt it would be
better for the model to do it, rather than provide the shift.  Arpad said the
output would be zero centered if DC offset equaled the threshold.  When they
are different the model gives the physical waveform.  Fangyi said it was
unnecessary.  Ambrish said most models would not find a differing offset.
Arpad agreed that we should not corner ourselves into an unlikely scenario.
Ambrish said the model could still shift even if they were the same.
Arpad said differing input and output offset precluded returning a zero
centered waveform from the model.  Ambrish agreed the model would have
to shift, but he did not see that as a limitation.  Fangyi just it should
only be necessary to add the offset to the waveform.  Arpad asked if it was
InOut, would NRZ Threshold go away?  Fangyi said it would still be needed/.
Arpad again asked if a new BIRD was needed. He read portions of the BIRD
draft, noted there was an ambiguity about "Rx pad".  He said the definition
should be improved for clarity about which Rx waveform we were talking about.
Bob noted that 197.3 was introduced, but we probably would not agree on 197.4.
Arpad said we should not take the BIRD out of Walter's hands, suggesting a
new competing BIRD should be written.  Bob said we should not have an early
vote on BIRD197.3.  Fangyi agreed to write a new BIRD.

AR: Fangyi Rao to write new BIRD for DC offset.

- Randy: Motion to adjourn.
- Bob: Second.
- Arpad: Thank you all for joining.


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Next meeting: 16 July 2019 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives
