[ibis-macro] Minutes from the 17 Jan 2012 ibis-atm meeting
- From: Mike LaBonte <mike@xxxxxxxxxxx>
- To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
- Date: Sat, 11 Feb 2012 13:52:03 -0500
Minutes from the 17 Jan 2012 ibis-atm meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 17 Jan 2012
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: Mike LaBonte
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
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:
--------------------------
Call for patent disclosure:
- None
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Review of ARs:
- None
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New Discussion:
Quick question from Arpad regarding which BIRDS to discuss:
- Arpad: Should we focus entirely on Analog BIRD proposals or look at
121.1 and 124.1, which might require less discussion?
- Walter: 121.1 is ready for review. 124.1 will be resubmitted.
- Arpad: Resubmitted as 124.2?
- Walter: yes.
- Bob: Does it involve substantial changes? Should it be a new BIRD?
- Walter: Agree with Bob, it will be submitted as a new BIRD.
- Arpad: We may slip 121.1 in at some point, but we'll defer the other.
Analog BIRD discussion:
- Arpad: Last week we agreed to table Walter's new tree syntax proposal.
- Arpad: Continuing the discussion... (shared his BIRD comparison slides).
- These slides will be used to capture our discussions/questions/info.
- Two new slides:
- one for SiSoft intrinsic models, one for Cadence's BIRD 144
- Walter, do you want to discuss your proposals?
- Walter: (sharing draft email with proposed template models)
- s4p example covers On Die S params.
- Thevenin examples Tx/Rx can replace typical BIRD 122 models.
- Thevenin examples can handle the classic I/V IBIS models.
- Reserved Model templates get their values from model specific
parameters with pre-defined names.
- If these are included in BIRD 116, BIRD122 would be withdrawn.
- Bob: This is a lot to absorb.
- Are there predefined reserved parameters for Thevenin templates?
- Aren't these "reserved" names for model specific parameters?
- This is a hard coded topology, right?
- Walter: Agreed, these are 4 hardcoded shortcuts to BIRD 116 circuits.
- Arpad: Shouldn't these be reserved parameters?
- How can you have model specific parameters with reserved names?
- Ambrish: So you're introducing a Reserved Model concept.
- Walter: Yes, but BIRD 144 also contains a list of allowed Touchstone files.
- Ambrish: They're two separate issues.
- Can you use a Reserved Model without AMI?
- Walter: We can remove "AMI" from Reserved Model names.
- The proposal is general.
- Ambrish: We could theoretically end up with many new Reserved Models.
- Walter: Yes, over time more could be added if they're justified.
- Ambrish: BIRD 116 can already handle all of this.
- Walter: The usage of Reserved Models is optional.
- The model maker can build their own general model if they want.
- Radek: I question the need for this predefined subcircuit model.
- Walter: They're simply 4 templates.
- Radek: The concept is clear, however,
- Reserved Models may not be sufficient in the future.
- The concept is not necessary
- Arpad: (returning to his summary slides and reviewing bullet points)
- Proposal could reduce file management burden.
- Proposal provides a shorthand notation.
- No one has yet discussed one additional issue - performance.
- Performance advantage because the tool knows it's a fixed topology?
- Closed form solution, etc., for fixed topology?
- Radek: No real performance advantage for these small LTI circuits.
- Ken: When we go "hard-coded" we end up with an explosion of new things.
- We've been on this path before.
- Original IBIS models -> insufficient -> invented External Models.
- This would follow the same path.
- Walter: AMI assumptions are all covered.
- AMI assumes impulse response which assumes LTI.
- These Reserved Models could describe all such models.
- Ken: If we support these we'll be adding them forever.
- Arpad: We had two solutions - general and hard coded topology.
- Is there an intermediate solution with a Reserved subcircuit name?
- Ken: Circuit descriptions are essentially a solved problem.
- We have ISS support, so why should this committee reinvent the wheel?
- Bob: Is this Reserved Modeling optional?
- Walter: Yes, the Reserved Models are just templates.
- Ken: This is not optional for the EDA tool.
- The EDA tool would have to support these hard coded models.
- Bob: Reserved Models need not be related to AMI?
- Arpad (back to Walter's email)
- This works when the parameters are there in the AMI file.
- How does it work if not tied to AMI?
- Doesn't it assume the params come from the AMI file?
- Walter: Yes, that is correct. I forgot about that.
- This shortcut is only for AMI use.
- Walter: The Thevenin circuits can cover every LTI, constant diff impedance.
- Complete representation of any classic IBIS LTI model.
- Vendors are doing this already, they're using S4P for On Die S-params.
- Randy: Where is the topology defined?
- Ken: The EDA tools have to know what it is.
- Arpad: We would have to define it in the spec.
- Arpad: (Comparing Walter's proposal and BIRD 144)
- Neither approach gives a functional advantage (BIRD 116 is general).
- Both offer reductions in file management issues for model makers.
- Both offer syntax shortcuts.
- Corner issues might still need to be addressed.
- BIRD 144 is a short cut to a Touchstone file.
- So, you can't reject one proposal but not the other for "hard coding."
- Ambrish: Touchstone is more general.
- Radek: Arpad is right (regarding both proposals being shortcuts).
- Bob: The direct connection to Touchstone is general.
- But knowing it's a direct connection to a Touchstone file is better.
- Radek: The best shortcut proposal is direct to Touchstone.
- Bob: Shortcut to Touchstone supports s6P, s8P, etc.
- Radek: Solution should be more general than to rely on the AMI file.
- Walter: These Reserved Models are optional.
- Radek/Ken: The tools would "have" to support these hard coded Models.
- Arpad: Walter, could you summarize the benefits of your proposal?
- Walter: Arpad, your slide covered the advantages nicely.
- Covers all On Die S-params.
- Gets rid of redundant files (simplifies model maker's life)
- Model maker need only add one small section to the IBIS file.
- Ambrish: I suggest we keep this proposal separate from BIRD 116.
- As Walter said, BIRD 116 is the most general.
- Walter: I'm fine with a separate approval process.
- Arpad: I agree.
- Bob: question for Walter
- We have a pre-defined model but it uses model specific variables?
- Randy: Only the topology itself is hard coded.
- James: We shouldn't have model specific parameters with reserved names.
- Radek: This is a misuse of "model specific."
- Walter: When someone programs an AMI model, chooses strength, tap
coefficients, registers on Tx or Rx model, there becomes a dependency
table (BIRD124) where for each programming it determines the impedances,
C_comps, etc. that go into the analog model.
- So, with Tx with 128 strengths, must create 128 models with 128
model selectors and 128 AMI files.
- Ambrish: Shouldn't the parameters be reserved?
- Walter: Making these parameters reserved makes them only useful with these 4
reserved models, so doesn't see the need.
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Next meeting: 24 Jan 2012 12:00pm PT
Next agenda:
1) Task list item discussions
-------------
IBIS Interconnect SPICE Wish List:
1) Simulator directives
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- » [ibis-macro] Minutes from the 17 Jan 2012 ibis-atm meeting - Mike LaBonte
