IBIS Macromodel Task Group

Meeting date: 19 Jun 2012

Members (asterisk for those attending):
Agilent:                    * Fangyi Rao
                              Radek Biernacki
Altera:                       David Banas
Andrew Joy Consulting:      * Andy Joy
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:

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Call for patent disclosure:

- None

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Review of ARs:

- Arpad & Walter to propose alternative to "Labels" as Dependency Table control
  - in progress

- Arpad to write a new revision of BIRD 117 and 118 to generalize references
  to parameters in files (.ami or any)
  - in progress

- Bob to propose a simpler way for addressing the needs of parameter passing
  under [External Model] and [External Circuit]
 - not done

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New Discussion:

Parameter Tree Keyword BIRD draft 4 discussion:

- Arpad: The draft now contains the fixed parenthesis and description.
  - These changes were made during last week's meeting, nothing new.
  - I would like to discuss this and perhaps vote to send it to the Open Forum.
  - Get an official BIRD # assigned.
- <no discussion or questions forthcoming>
- Eckhard: motion to vote to submit it to the Open Forum.
- Arpad: second the motion.
- Walter: I have no objections to this proposal.
- Arpad: Are there any objections?
- <none forthcoming> Unanimous approval.

BIRD 117.4 draft 6 and BIRD 118.3 draft 5 discussion:

- Arpad: The draft now contains the fixed parenthesis and description.
  - Summarize the overall changes:
  - Generalized parameter file references.  No longer exclusive to AMI models.
  - Generalized [External Model] and [External Circuit] parameters from AMI
    style parameter trees.
  - This led to another idea, submitted in the BIRD draft we just voted on,
    to allow the tree in the IBIS file.
  - <no discussion or questions forthcoming>
- Curtis: motion to vote to submit them to the Open Forum.
- Eckhard: second the motion.
- Arpad: Are there any objections?
- <none forthcoming> Unanimous approval.

BIRD 116 discussion:

- Arpad: Summarize the changes:
  - Simply added IBIS-ISS as a supported language.
  - We call it "IBIS-ISS" in the description, but use "ISS" in language names.
  - Should we call it "IBIS-ISS" or "ISS"?
- Walter: I'd like to restate:
  - I fully support this proposal.
  - At some point in the Open Forum process I will draft ISS reference circuits.
  - These will correspond to the reference topologies from BIRD 122.
  - At that point I will then recommend that BIRD 122 be rejected.
- Walter: I think we should use "IBIS-ISS"
- Arpad: I'll make a version with the "IBIS-ISS" change.
  - Could we vote to submit that version I will create?
- Walter: motion to vote on the modified version.
- Dan: second the motion.
- Arpad: Are there any objections?
- <none forthcoming> Unanimous approval.

BIRD 150 discussion:
- Arpad: Walter mentioned before the meeting that he was not quite ready.
  - I'll keep this on the agenda for next week.
- Walter: Hopefully I'll have something ready by then.

BIRD 125 Package Modeling discussion:
- Arpad: <shared "IBIS-AMI Analog Modeling" power point presentation>
  - I've pulled together enough to get started.
  - We should get started as this is our next big topic.
  - This can be used to document our discussions.
  - I've updated this to reflect the latest parameter tree and file BIRDs.
  - Grayed out the AMI keyword section.
  - BIRD 116 introduced use of IBIS-ISS.
  - BIRD 125 also uses IBIS-ISS.
  - Summarizes legacy package model handling.  "Miraculous" connections rely on:
    - Implicit die pads with a one-to-one pin to pad relationship.
    - [Pin] names in IBIS file must match [Pin Numbers] names in .pkg file.
  - BIRD 125 proposes a second column under [Pin Numbers] for die pad.
  - IDP_<pin name> is an implicit die pad.  ISS subcircuit needs a die node.
  - Explicit pad2 example.  Node on die declared by [Node Declaration] keyword
    in legacy IBIS.
  - [Package Circuit] keyword defines the ISS circuit.
  - Simple Example, all implicit pads.
    - nodes 5, 6, 7, 8 on one side and IDP_8, IDP_7, IDP_6, IDP_5 on the other.
  - More complicated example, number of pads and pins don't match.
    - Use [Node Declaration] to define pad node names.
- Walter: I think I understand what you're doing, and I think it is okay.
  - I'd like to describe what I think we need to deal with:
  - Signal line might have one pin to multiple buffers.
  - Power, however, might have 10 pins to 20 pads and vice-versa.
  - In reality it might be even more like 100 pins to 500 pads.
  - Need a power distribution model for the package.
  - On die, high frequency, wavelength < chip size.
  - Package power distribution model for certain subsets of the pads.
  - On die power models between pads.
  - Extend the scheme to handle:
    - which buffers attach to which ports on the on-die model
    - which die pads go to which ports on the power distribution package.
- Arpad: I agree.
  - I have one problem to highlight that is not yet written up here.
  - Problem: Legacy IBIS the [Pin] goes to the buffer model.
  - Okay with a one-to-one pin to pad mapping.
  - Two different pads might have two entirely different buffer models.
  - If we need the signal on a pin to join or split to get to a pad... trouble.
- Walter: I believe there is a solution available.
  - We could introduce a Model Connection Protocol wrapper.
  - We could use a parameter tree syntax to define connections such as:
  - One port on a subcircuit goes to -> these pins on the package.
  - One port on a subcircuit goes to -> these ports on die side.
  - One more layer of abstraction.
    - On die power distribution defines buffers attached.
  - Port info in wrappers for package and on-die models.
  - MCP by Brad Brim, while I have objections to its format, could be applied.
- Arpad: Introduce a Pad keyword similar to the [Pin] keyword.
  - It would associate a pad on the die with a buffer.
  - Simpler?
- Walter: Perhaps.
  - Let's make real examples.
  - Then we can try various techniques on the real examples.
  - We can look at on-die power and go to IC vendors for their input.
  - We can look at package power modeling and go to package vendors and others.
  - Get their input on whether the models are buildable and useful.
- Arpad: If we go to buffers <-> pad then we need a new keyword.
- Walter: I think changes to legacy IBIS should be very conservative.
  - If we can stay outside IBIS in the package model it is preferable.
  - Creating power distribution models these days is a science project.
    - expensive, may not want to give out the details
    - that information might not belong in the IBIS file.
- Arpad: Okay, I think this is a good stopping point for this week.
- Walter: I think we should ask Brad Brim to join in.
- Arpad: Good idea.
- Walter: I've described what SiSoft wants.
- Arpad: Oh, I see, get early feedback from people.
- Walter: We need to see other opinions.
  - We might all be myopic in seeing only our customer's needs.
- Arpad: I will create an "invitation" email to encourage people to attend.

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Next meeting: 26 Jun 2012 12:00pm PT

Next agenda:
1) Task list item discussions

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IBIS Interconnect SPICE Wish List:

1) Simulator directives