[ibis-macro] Minutes from the December 2, 2008 ibis-atm meeting
- From: <rrwolff@xxxxxxxxxx>
- To: <ibis-macro@xxxxxxxxxxxxx>
- Date: Thu, 4 Dec 2008 09:01:31 -0700
Minutes from the Dec. 2, 2008 IBIS ATM meeting are attached.
Randy
IBIS Macromodel Task Group
Meeting date: 2 December 2008
Members (asterisk for those attending):
Ambrish Varma, Cadence Design Systems
Anders Ekholm, Ericsson
* Arpad Muranyi, Mentor Graphics Corp.
Barry Katz, SiSoft
* Bob Ross, Teraspeed Consulting Group
Brad Brim, Sigrity
Brad Griffin, Cadence Design Systems
* David Banas, Xilinx
Donald Telian, consultant
Doug White, Cisco Systems
Essaid Bensoudane, ST Microelectronics
Fangyi Rao, Agilent
Ganesh Narayanaswamy, ST Micro
Gang Kang, Sigrity
Hemant Shah, Cadence Design Systems
* Ian Dodd, Agilent
Joe Abler, IBM
* John Angulo, Mentor Graphics
John Shields, Mentor Graphics
Ken Willis, Cadence Design Systems
Kumar
Lance Wang, Cadence Design Systems
Luis Boluna, Cisco Systems
* Michael Mirmak, Intel Corp.
Mike LaBonte, Cisco Systems
Mike Steinberger, SiSoft
Mustansir Fanaswalla, Xilinx
Patrick O'Halloran, Tiburon Design Automation
Paul Fernando, NCSU
* Pavani Jella, TI
* Radek Biernacki, Agilent (EESof)
* Randy Wolff, Micron Technology
Ray Comeau, Cadence Design Systems
Richard Mellitz, Intel
Richard Ward, Texas Instruments
Sam Chitwood, Sigrity
Sanjeev Gupta, Agilent
Shangli Wu, Cadence Design Systems
Sid Singh, Extreme Networks
Stephen Scearce, Cisco Systems
Steve Pytel, Ansoft
Syed Huq, Cisco Systems
Syed Sadeghi, ST Micro
* Terry Jernberg, Cadence Design Systems
Todd Westerhoff, SiSoft
Vikas Gupta, Xilinx
Vuk Borich, Agilent
Walter Katz, SiSoft
Zhen Mu, Cadence Design Systems
------------------------------------------------------------------------
Opens:
- None
--------------------------
Call for patent disclosure:
- No one declared a patent.
-------------
Review of ARs:
- Michael M: Confirm with Synopsys whether "used by permission" can be used
as the official indicator on relevant documents.
- Michael wrote another email to Synopsys with no response back yet
- Arpad: Write parameter passing syntax proposal (BIRD draft)
for *-AMS models in IBIS that is consistent with the
parameter passing syntax of the AMI models
- TBD
- TBD: Propose a parameter passing syntax for the SPICE
- [External ...] also?
- TBD
- Arpad: Review the documentation (annotation) in the macro libraries.
- Deferred until a demand arises or we have nothing else to do
-------------
New Discussion:
Brain storming session on what the majorly overhauled IBIS specification should
look like.
Bob: Initially was reluctant to overhauling IBIS
- Arpad: Clarify your statement from the last set of minutes about opposing
a major change for C_comp
- Bob: If a new feature requires restructuring fundamental structures of IBIS,
making old versions of IBIS incompatible, he is opposed to this
- Arpad: We should focus on the idea of starting over with a new IBIS spec,
maybe with a different name
- Bob: Ok with this idea.
- Lots of companies with current IBIS solutions will maintain support for
current IBIS. New IBIS would need link to old IBIS.
Michael: It is helpful to clarify assumptions of things we like about existing
IBIS and what we need a new IBIS for.
- Arpad: What would be the general feel of new IBIS?
- I-V and V-t curves still or equations?
Michael: We must look at a higher level, what is needed?
- Pin information, measurement info, modeling info, packaging info?
- Arpad: Behavioral models are useful for circuit designers, but need to cover
the level of entire systems
- John: There are three issues: assigning models to the system, how do you
simulate them and how to interpret the simulation results
- Michael: Agrees with John.
- One needs to assign a model, but represent models of devices and whole
systems.
- Solution must be truly universal, work close to the same in multiple tools.
- Randy: Need to model buffers separately from packages and system level models
that need netlists
Arpad: What is IBIS lacking right now?
- Michael: At a low level: not enough controllability - example is coefficients
for equalization. Data is too hard to extract.
- At a high level: three major assumptions in current spec that aren't
appropriate anymore:
- typ/min/max concept, with three corner format defining an envelope - having
waveform correlation with exact overlays is not needed in SerDes
- post layout is not as strong an interest to many people
- IBIS is not setup well for pre-layout simulation.
- Arpad: Tables make it difficult to deviate away from corner concept, while
equations are better suited to allowing more control over PVT
variation.
Arpad: Is this the right group of people to do the work, or should we just make
the list in this group and form a new subcommittee?
- Michael: Sending this to the Open Forum will end up back in the same group
to implement.
Arpad: Let's form a list of what we need.
- Pavani: Most models at TI are differential. It is inconvenient correlating to
SPICE. Most buffers they have been able to model ok.
- Several power supplies on a single buffer are difficult to model.
- Customers currently don't express interest in accuracy, ok with IBIS
models.
- Arpad: Why is there still a concept of IBIS being inaccurate?
- Pavani: Due to limitations such as the difficulty of modeling a buffer with
several pullup structures to different power supplies.
- Arpad: There are limited keywords now to describe this situation.
Pavani: IBIS serves its purpose for her customers.
- Arpad: What is its purpose?
- Bob: New IBIS could embrace existing IBIS applications but expand to include
others.
- New IBIS could be directed towards some advanced technologies, but may be a
buffer only spec.
- Other formats could handle package, etc.
- Would like to let IBIS remain supported forever for low end technology.
Arpad: If we come up with a new IBIS, it feels like it may end up looking like
an AMS language. Is it worthwhile to come up with a new language from
scratch when there are languages existing?
- Radek: IBIS describes acceptable limits as well as buffers.
- Moving forward need eye masks, etc. to address the measurement side while
still focusing on the behavior side.
- Arpad: You can not add eye diagram specs without a new keyword currently. In
AMS, you can define this easily.
- Michael: Whatever we decide on has to be easy to use and easy to extract.
- It is no longer IBIS vs SPICE, behavioral has won, but IBIS is losing as
the behavioral choice.
- There are great advantages with IBIS like measurement point that are easily
described in the model and left up to the tool to measure.
- May be easy to extract new data in a company with an AMS type flow, but
other companies will have difficulty extracting new models.
Arpad: The problem with AMS is it is unfamiliar, right?
- Michael: It is hard to use.
- Arpad: Yes, VHDL-AMS is hard. But do we benefit from studying these
languages?
- Take the best of everything and make a new language.
- Bob: Need to look at linking models such as making executables.
- AMS is just not part of the design stream for most of the tools.
- Mathcad or C may be more appropriate.
- If using a language based format, how do you turn a silicon model into the
right equations?
Arpad: SPICE is familiar, maybe start with a SPICE-like syntax but expand it.
Would this be reasonable?
- Michael: Does this address our list of needs?
- Arpad: A new SPICE must be expanded to cover the list such as to add pin lists
or measurement specs.
- Bob: We just started with a subset of a SPICE language. How to now extend it?
- Arpad: Starting with SPICE-like syntax might just be best because it is
familiar.
- Bob: You must understand how the model will be processed.
- You must have motivation for EDA vendors to support it because it does
what we need it to.
- Radek: IBIS allowed you to match simulations to measurements, it maps
components,
and it provides measurements.
- We must follow a path of standardization.
- You need to be able to run batch simulations, so this requires many
standardized parameters, temp vs. temperature, Farenheit vs. Celcius.
Arpad: We will continue this topic next week. He will come up with other
questions.
Next meeting: 09 December 2008 12:00pm PT
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