IBIS Macromodel Task Group

Meeting date: 22 March 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
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:

- AR: Arpad to send draft 18 of BIRD213.1 to the ATM list.
  - 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 March 15th
meeting.  Randy moved to approve the minutes.  Ambrish seconded the motion.
There were no objections.

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New Discussion:

BIRD213.1 draft 19, PAMn:
Arpad shared draft 19.  He had looked through IBIS 7.1 to find mentions of the
existing PAM4 parameters, possible contradictions, etc.  Based on that
investigation, he had emailed ATM a list of suggestions and created a draft 19
including them.

On page 273, in the Description of Rx_Receiver_Sensitivity, the existing PAM4
Threshold parameters are mentioned.  Arpad had added the new PAM_Thresholds
parameter to the sentence.  The group agreed with the change.  Ambrish asked
whether we could consider making the existing PAM4 parameters illegal, since the
new PAMn support parameters are being added.  Bob, Walter and others said that
making the PAM4 parameters illegal is not possible because of the longstanding
IBIS policy of maintaining forward compatibility (you can take a file with an
older version and increase the version value and still have a legal model).

Ambrish then asked whether we should create a blanket statement that the new
parameters are preferred over the existing PAM4 parameters.  Could we then avoid
having to enumerate the new and old parameters in multiple locations?  The group
considered this but ultimately decided that it wasn't necessary.  There weren't
enough places in the text where we had to enumerate both the existing and new
parameters to make it worthwhile to create new more general language.

Randy said that we planned to add a sentence encouraging usage of the new
parameters, but we hadn't yet drafted it.  He said we should do it if we want
model makers to transition to the new parameters.

On page 278, in the Usage Rules for the existing parameter Modulation, Arpad had
added a copy of the sentence stating that Modulation and Modulation_Levels shall
not both be present.

On page 280, in the Usage Rules for the PAM4_Mapping, Arpad had extended the
list of conditions under which PAM4_Mapping is ignored to include when
Modulation_Levels is declared.  The group agreed with the extension of the
existing language for now.  Ambrish asked whether we should consider allowing
the use of PAM4_Mapping with the new Modulation_Levels because there is nothing
analogous to the PAM4_Mapping parameter in the new PAMn parameters.  Arpad
agreed that mapping is the one area where the new parameters are not a superset
of the PAM4 parameters.  Ambrish said someone who wants to specify Gray code
will be inclined to use the old parameters instead of the new ones.  Bob and
Arpad said that if a model maker wants to specify Gray code they must use the
old parameters.  Arpad added a note to the draft stating that we should think
about this issue later:  Should we allow PAM4_Mapping to be used with the new
modulation parameters?

The group then returned to rewriting the introduction paragraphs in 10.7.  Arpad
added a new sentence extending the historical sequence and stating that IBIS 7.2
introduced (will introduce) PAMn support.  Arpad and the group added sentences
stating that the new parameters are preferred, and encoding is not specified
with the new parameters because it is expected to be provided by the EDA tools.

Ambrish noted that the sentences related to waveform data, transitions, etc.,
were generally applicable to NRZ, PAM4, and PAMn.  Randy suggested that these
sentences could be moved to page 223 in the section that defines the symbol_time
parameter for AMI_Init() (and possibly also in the AMI_GetWave() section).

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

AR: Arpad to send an updated draft 19 of BIRD213.1 to the ATM list.
    
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Next meeting: 29 March 2022 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives
