                                             
IBIS Macromodel Task Group

Meeting date: 24 Jan 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
			    * Feras Al-Hawari
Celsionix:                    Kellee Crisafulli
Cisco Systems:                Ashwin Vasudevan
                              Syed Huq
Ericsson:                     Anders Ekholm
IBM:                          Greg Edlund
Intel:                        Michael Mirmak
LSI Logic:                    Wenyi Jin
Maxim Integrated Products:    Mahbubul Bari
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:

- Arpad: Minutes from last week will be sent to Mike for posting

- Arpad: There will be no meeting next week due to DesignCON

- Arpad: Can we remove the last agenda item?
  - Walter: Yes it can be removed

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Call for patent disclosure:

- None

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Review of ARs:

- None (may find some after review of minutes from last week)

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New Discussion:

IBIS 5.1 parser plans:
- Bob: The editorial committee has been discussing this
  - Use_Init_Output is deprecated
  - Not going to document executable model flow changes in 5.1
  - 5.1 rules will apply to 5.0 models
  - 5.0 models can have the relaxed syntax allowed in 5.1
  - We can discuss this at the DesignCON summit
- Arpad: If Version is absent 5.0 rules will apply?
  - Maybe it should default to 5.1
- Bob: A BIRD would be needed for that
  - BIRD 126 already covers this well
  - It mostly deprecates 5.0, with exceptions
- Arpad: I like the idea but if 5.0 rules are not used we should not default to 5.0
- Radek: It is not 100% clear what to do if Use_Init_Output is present
- Walter: If AMI_Version is 5.1 Use_Init_Output will be flagged as an error
  - In most cases we can add AMI_Version and delete Use_Init_Output

Walter showed an email about Analog Buffer Modeling:
- Walter: No one has objected to these statements

Walter showed another email with conclusions:
- Walter: Point 2 is not 100% true
  - With just [Ramp] the V-T can't be represented
  - External Model could have a D-A with a PWL to give the K(t) function
  - This will represent the behavior of any LTI driver
- Walter: Point 4 is about it being easy to accurately describe analog behavior
  - Every swing setting has a different Voh and impedance
  - An IBIS file can be generated with many [Model Selector]s, many AMI files
  - Simulators often do quadratic rounding of ramp corners
  - Would like to have four internal reference models with reserved subckts
- Feras: We don't need the new keywords
  - IBIS-ISS subckts can model it
- Walter: The reference subckt names are not new keywords
- Arpad: Is this about standard ISS files or hardcoded circuits?
- Feras: You proposed 4 keywords in an email
- Walter showed a previous email
- Walter: We can ignore the Reserved_Model keyword
  - I would only like these subcircuit names and files to be reserved
  - They would not have to be supplied with each model
- Feras: Would it be inserted in the IBIS file, not external?
  - We should be able to include an analog model with or without AMI
- Walter: The BIRD allows that
- Arpad: BIRD 118 can be extended for this purpose
- Ambrish: It should allow linking just any file to the AMI section of IBIS
- Walter: Adge Hawes will have related presentation at DesignCON
  - It will show what vendors need
- Arpad: If we allow just any file we have to spell out the allowed syntax
  - Those changes can be made though
- Feras: You have to have an AMI model present
  - The [Algorithmic Model] section should not be required
- Walter: It's OK if this is used only where AMI is present
- Ambrish: How would we handle it when there is no AMI?
- Arpad: We could have a file pointer without relying on the AMI keyword
- Feras: Users must be able to use models with or without DLLs
- Walter: There will be a presentation about a model with 128 Touchstone files in it
- Arpad: We just need a keyword other than AMIfile
  - The file format is tree format just like AMI though
- Kumar: AMI does not own the tree format
- Walters: We should listen to what IC vendors want
- Ambrish: How would corners be chosen?
- Arpad: The GUI will have to let users choose
- Walter: It could be done as an Include statement
- Radek: So this is not a reserved parameter, but a reserved name
- Walter: One problem is having two different models with the same name
  - There will be only one of each of these reserved models, no collisions
- Ambrish: That is for the user and vendors to deal with, not the spec
  - If it's hardcoded in the tool we can't change it
- Walter: Then a file can be created for anything new
- Fangyi: Why are there 4 reserved file names?
- Feras: We can publish templates and those can be copied
  - How will the user find the actual subcircuit?
- Walter: It would be in the spec
  - It would also be supplied as files
  - Tools might handle it efficiently through internal means
- Fangyi: Why can't vendors use a different file name?
- Walter: Then we will have file management problem
- Feras: There are many other circuit types needed
- Walter: Nothing prevents them from doing that
- Ambrish: Templates that only work for AMI defeat the purpose
- Walter: IBIS-ISS was created for AMI analog models and interconnect
  - The only application right now is AMI, until we have BSS
- Arpad: The 6 points are all correct
  - Why do we need a shorthand for these circuits?
- Walter: At this point I only want them as reference circuits
- Radek: A circuit file with no reserved name causes no problem
- Walter: I have a model that has 260,000 combinations
- Arpad: What benefits do the 4 circuit bring us?
- Walter: They cover all known SerDes standards and contemplated for 4 years
- Arpad: We can just supply the files
- Kumar: These circuit models are an approximation
  - The parameters are not cast in stone
- Fangyi: Why do we still need Touchstone if these are accurate?
- Walter: That is needed for broadband
  - Complicated subckts would be needed, but they are proprietary
- Fangyi: So these do not cover everything

- Feras: What if someone wants non-linear models?
- Walter: ISS only allows linear
- Feras: [External Model] allows other non-linear languages
- Walter: I have not seen a channel where a non-LTI model makes a difference
  - Industry tools all use LTI models like MatLab, HSS-CDR
- Kumar: We can't restrict ourselves to what those tools do
- Fangyi: This analog model is not just for AMI
  - Rambus did experiments showing that
- Kumar: We can't assume superposition will apply into the future
- Walter: LTI is more true as speeds go higher

- Fangyi: Can parameter names be changed for the reserved models?
- Walter: No
- Ambrish: That makes them reserved parameters
- Walter: Not by the AMI definition
  - They could be called pseudo-reserved
  - We need to remember that there are 3 groups: users, EDA vendors, IC vendors
- Ambrish: The IC vendors tend to not be well versed in these issues

Meeting ended.

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Next meeting: 7 Feb 2011 12:00pm PT

Next agenda:
1) Task list item discussions

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IBIS Interconnect SPICE Wish List:

1) Simulator directives
