IBIS Macromodel Task Group

Meeting date: 10 May 2022

Members (asterisk for those attending):
Achronix Semiconductor:       Hansel Dsilva
Amazon:                       John Yan
ANSYS:                      * Curtis Clark
                            * Wei-hsing Huang
Cadence Design Systems:     * Ambrish Varma
                            * Jared James
Google:                       Zhiping Yang
Intel:                        Michael Mirmak
                              Kinger Cai
                              Alaeddin Aydiner
Keysight Technologies:      * Fangyi Rao
                              Majid Ahadi Dolatsara
                              Ming Yan
                              Radek Biernacki
                            * Rui Yang
Luminous Computing            David Banas
Marvell                       Steve Parker
Mathworks (SiSoft):           Walter Katz
                              Mike LaBonte
Micron Technology:          * Randy Wolff
                            * Justin Butterfield
Missouri S&T                  Chulsoon Hwang
SAE ITC                       Michael McNair
Siemens EDA (Mentor):       * Arpad Muranyi
Teraspeed Labs:             * Bob Ross
Zuken USA:                    Lance Wang

The meeting was led by Arpad Muranyi.  Curtis Clark took the minutes.

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Opens:

- None.

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Review of ARs:

- Arpad to send the latest draft of BIRD219.1 to Randy to be submitted to the
  Open Forum as BIRD219.1.
  - 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 May 3rd
meeting.  Ambrish moved to approve the minutes.  Bob seconded the motion.
There were no objections.

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New Discussion:

PAMn BIRD 213.1 draft 23:
Arpad reviewed the new language Ambrish had proposed in the description of
clock_times.  Ambrish had suggested:
  ...offset is defined by Reserve Parameters PAM_Offsets or PAM4_UpperEyeOffset,
  PAM4_CenterEyeOffset, and PAM4_LowerEyeOffset.
The previous version of this text has used "and" in place of "or".

Ambrish had also suggested an additional sentence.  With a slight change in
wording, the group arrived at:
  In the absence of these parameters, offset is assumed to be 0.
  
The group approved of Ambrish's proposed changes.
  
Arpad led a review of the rest of the highlighted sections that had been
modified for this draft.  The group agreed with all of the changes.

Fangyi offered a comment on the PAM_Offsets Usage Rules.  He referred to the
last sentence of the second paragraph and the first sentence of the third
paragraph:
  ... Note: This implies that PAM_Offsets already includes the
  Rx_Clock_Recovery_Mean.
  
  If the AMI Reserved Parameter Modulation_Levels is defined and these offset
  values are not declared, the EDA tool is expected to use a default value
  of 0.0 for each offset parameter...
and said that taken together these two sentences could give the impression
that Rx_Clock_Recovery_Mean is never considered.  He asked if that was the
intent.

The group spent the meeting discussing the interactions between PAM_Offsets and
Rx_Clock_Recovery_Mean.  The group noted that for the existing PAM4_XXXEyeOffset
parameters the Other Notes section stated that:
  In statistical analysis, offset from the center of the nominal eye shall
  include Rx_Clock_Recovery_Mean and either the PAM4_UpperEyeOffset,
  PAM4_CenterEyeOffset and PAM4_LowerEyeOffset.
  
However, for the new PAM_Offsets, the group decided that Rx_Clock_Recovery_Mean
is not used in addition to PAM_Offsets.  For Modulation_Levels equal to 2 (NRZ),
the PAM_Offsets value is ignored and Rx_Clock_Recovery_Mean is considered.  For
Modulation_Levels > 2, Rx_Clock_Recovery_Mean is ignored and PAM_Offsets values
should include the offset described by Rx_Clock_Recovery_Mean.

Randy then noted that Rx_Clock_Recovery_Mean is also mentioned in the
Rx_Decision_Time, so we have to consider that interaction too.  Bob said that we
have to describe everything IBIS allows, not just what we would prefer models to
do.

Arpad captured the group's modified language for the PAM_Offsets Usage Rules.
Arpad took an AR to send out draft 24, and he encouraged everyone to review it
to make sure it properly captured the intent and to see whether the phrasing
could be improved.

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

AR: Arpad to send BIRD213.1 draft 24 to the ATM list.
    
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Next meeting: 17 May 2022 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives