IBIS Macromodel Task Group

Meeting date: 24 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 BIRD213.1 draft 25 to the ATM list.
  - Done.
  
- Walter to alter draft 25 by creating a list of combinations and behaviors for
  PAM_Offsets Usage Rules.
  - 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 17th
meeting.  Randy moved to approve the minutes.  Walter seconded the motion.
There were no objections.

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New Discussion:

PAMn BIRD 213.1 draft 25 (plus Walter's proposed changes):
The group resumed discussion of the PAM_Offsets Usage Rules by reviewing the new
language proposed by Walter.  Walter said the point of the section is to
eliminate confusion about PAM_Offsets' interaction with other parameters.
Walter said there's a nominal sample time based on all of our methodologies, and
with PAM_Offsets we adjust the sample time of the kth eye by the kth value in
PAM_Offsets.  The issue here is how to carefully define the nominal sample time.

The group reviewed Walter's proposed order of precedence in determining the
nominal sample time in statistical flow.  It noted that if Rx_Decision_Time is
provided, then it takes precedence over Rx_Clock_Recovery_Mean (this is per the
Usage Rules for Rx_Decision_Time in IBIS 7.1).

Fangyi reviewed some differences in this new proposal relative to previous
drafts.  In the new draft, Rx_Clock_Recovery_Mean and the PAM_Offsets values
would both be used at the same time (unless Rx_Decision_Time is specified, in
which case it overrides Rx_Clock_Recovery_Mean).  Fangyi also observed that the
language stating that PAM_Offsets' value is ignored for NRZ had been removed.
After discussing these points, the group decided to reverse the decisions it
had made in past meetings.  The special case for NRZ is removed, which
simplifies the specification.  The PAM_Offsets values are applied in addition to
Rx_Clock_Recovery_Mean, which makes the handling analogous to the legacy
PAM4_XXXEyeOffsets.

Ambrish noted that "nominal sample time" is a newly defined concept, but not a
new parameter.  After discussion, the group agreed to use nominal_sample_time,
which is similar in syntax to the ideal_time terminology used in the
Rx_Clock_Recovery_XXX parameters.  Fangyi asked whether the statement, "EDA tool
determines sample time", which was used in cases when neither Rx_Decision_Time
nor Rx_Clock_Recovery_Mean were specified, was clear enough.  Ambrish suggested
using the existing ideal_time terminology and definition in this context too.
The group rewrote the expressions for nominal_sample_time in terms of ideal_time
where appropriate.  For example (case 2 and case 5):
  nominal_sample_time = ideal_time + Rx_Clock_Recovery_Mean
  
Arpad captured these changes and other grammatical and syntax corrections in a
new draft 26.
   
Ambrish suggested we consider replacing the actual_time terminology in the
Rx_Clock_Recovery_XXX parameter definitions with the new nominal_sample_time
terminology.  Others suggested this might be a good idea for a different BIRD.

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

AR: Arpad to send BIRD213.1 draft 26 to the ATM list.
    
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Next meeting: 31 May 2022 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives