                                             
IBIS Macromodel Task Group

Meeting date: 25 Oct 2011

Members (asterisk for those attending):
Agilent:                    * Fangyi Rao
                            * Radek Biernacki
Altera:                     * David Banas
Ansys:                        Samuel Mertens
                            * Dan Dvorscak
                            * Curtis Clark
Arrow Electronics:            Ian Dodd
Cadence Design Systems:       Terry Jernberg
                              Ambrish Varma
Celsionix:                    Kellee Crisafulli
Cisco Systems:                Ashwin Vasudevan
                              Syed Huq
Ericsson:                     Anders Ekholm
IBM:                          Greg Edlund
Intel:                        Michael Mirmak
LSI Logic:                    Wenyi Jin
Mentor Graphics:            * John Angulo
                              Zhen Mu
                            * Arpad Muranyi
			      Vladimir Dmitriev-Zdorov
Micron Technology:            Randy Wolff
NetLogic Microsystems:        Ryan Couts
Nokia-Siemens Networks:     * Eckhard Lenski
QLogic Corp.                  James Zhou
Sigrity:                      Brad Brim
                            * Kumar Keshavan
                              Ken Willis
SiSoft:                     * Walter Katz
                              Todd Westerhoff
                              Doug Burns
			    * Mike LaBonte
Snowbush IP:                  Marcus Van Ierssel
ST Micro:                     Syed Sadeghi
Teraspeed Consulting Group:   Scott McMorrow
                            * Bob Ross
TI:                           Casey Morrison
                              Alfred Chong
Vitesse Semiconductor:        Eric Sweetman
Xilinx:                       Mustansir Fanaswalla

The meeting was lead by Arpad Muranyi

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Opens:

- Mike: Europe DST change is this weekend, US Nov 6

--------------------------
Call for patent disclosure:

- None

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Review of ARs:

- Arpad prepare slides for today on corners
  - Done

- Mike post Jitter BIRD
  - Done

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New Discussion:

Meeting schedule:
- Arpad showed a list of future meeting dates
- Some conflict with summits
- We will not meet Nov 15 and 22, Dec 27

Arpad showed Notes on Corners in IBIS (BIRD 140):
- Slide 2:
  - IBIS 1.1 note on data derivation of corners
  - Arpad: It was felt that min/max could be scaled from typical
- Slide 3:
  - IBIS 2.1 relaxed the rules
- Slide 4:
  - Page 174 requires min and max values "for all remaining keywords"
  - Examine which keywords fall after that statement
  - Arpad: We can't go by that strictly
    - Recent spec changes may not have observed it
- Slide 5:
  - Arpad: C_Comp is independent even where correlation is known
  - Defines "conservative approach" as max=slow, min=fast
- Slide 6:
  - Arpad: More ringing could slow down effective performance
    - We avoided defining it for that reason
- Slide 7:
  - Arpad: Does IBIS min = AMI slow and IBIS max = AMI fast?
  - C_comp is not the only questionable parameter
- Slide 8:
  - BIRD 133 [C Comp Corner]
  - Walter's proposal: let EDA tool decide until BIRD 133 approved
    - Use new keyword after that
    - Kumar: Does AMI Corner format define this?
    - Walter: It is typ/slow/fast, not typ/min/max
    - Bob: There are no GT/LT requirements
  - Problems:
    - [C Comp Corner] is optional
      - What does tool do if absent?
    - There are other independent parameters
- Slide 9:
  - Other independent keywords:
    - [Diff Pin] tdelay_***
    - [Rgnd], [Rpower], [Rac], [Cac]
    - [* Series]
    - [External Model], [External Circuit]
- Slide 10:
  - Arpad proposes extending IBIS to 5 corners, adding slow and fast
- Slide 11:
  - When slow not present max is used for slow
  - When fast not present min is used for fast
- Slide 12:
  - Why have a default that is opposite of the intuitive approach?
- Slide 13:
  - We may need 6 corners because AMI_typ may not equal IBIS_typ
- Slide 14:
  - Summary

- David: On slide 5 it is fundamental that the tool makes the choice
  - IBIS is a datasheet, not a model
  - We are getting away from our roots
- Walter: People generally have a good idea of slow and fast
- David: We know that min is faster for C_comp
- Walter: Sometimes C_comp is larger for the fast corner

- Walter: Disagree on using min for slow and max for fast
  - Model makers should document what they are doing
- David: This would have us using reverse order of current practice for C_comp
- Bob: IBISCHK will warn for min > max
- David: On slide 11 is say min is fast corner

- Walter: People want more than three corners
  - We should do this in a general way
- Arpad: Simulators can't just do what they do now because the spec is not clear
- Walter: In 5.1 they can use [C Comp Corner]

- Kumar: Min/typ/max is a numerical concept
  - It doesn't map to typ/slow/fast
  - With 5 corners do I simulate all 5 or just three?
- David: Complexity creates more work
- Walter: In 5.1 there should at least be a comment
  - Should this be done so the program can read it?
- Kumar: A comment is not a major, fundamental change
- Walter: We should solve the fundamental C_comp problem with BIRD 133
- Radek: We should consider a long term solution
  - This needs to address all parameters, not just C_comp
  - Extending BIRD 133 to other parameters would require more keywords
  - In Arpad's proposal 4th and 5th columns would only be needed for C_comp
  - Comments are welcome but users might not see them in large IBIS files
- Arpad: We could use 5 columns for C_comp for now
  - The overwriting mechanism is confusing
- Bob: I oppose adding the 2 more corners
  - Tools would have to handle it forever
- Kumar: A new keyword could document the C_comp mapping
- Arpad: What about the other problem parameters?
- Bob: Params like [R Series] not derived from silicon are a problem
  - We will not solve those with new keywords
- Walter: Associating ISS subckts with typ/slow/fast would be better
  - We should vote to use either Bob's approach or Arpad's
- Bob: I'm prepared to move forward on the C_comp BIRD

- Arpad: What does AMI Corner align with?
- Walter: It aligns with data derivation
- Arpad: C_comp is still needed for AMI models
- Walter: [C Comp Corner] fixes that

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Minutes by Mike LaBonte

Next meeting: 01 Nov 2011 12:00pm PT

Next agenda:
1) Task list item discussions

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IBIS Interconnect SPICE Wish List:

1) Simulator directives
