[ibis-macro] Minutes from the 8 Jan 2013 ibis-atm meeting
- From: Mike LaBonte <mike@xxxxxxxxxxx>
- To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
- Date: Tue, 8 Jan 2013 16:57:12 -0500
Minutes from the 8 Jan 2013 ibis-atm meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 08 Jan 2013
Members (asterisk for those attending):
Agilent: * Fangyi Rao
* Radek Biernacki
Altera: * David Banas
Julia Liu
Hazlina Ramly
Andrew Joy Consulting: Andy Joy
ANSYS: Samuel Mertens
* Dan Dvorscak
* Curtis Clark
Steve Pytel
* Luis Armenta
Arrow Electronics: Ian Dodd
Cadence Design Systems: Terry Jernberg
Ambrish Varma
Feras Al-Hawari
Brad Brim
Kumar Keshavan
Ken Willis
Cavium Networks: Johann Nittmann
Celsionix: Kellee Crisafulli
Cisco Systems: Ashwin Vasudevan
Syed Huq
Ericsson: Anders Ekholm
IBM: Greg Edlund
Intel: * Michael Mirmak
Maxim Integrated Products: Mahbubul Bari
Hassan Raghat
Ron Olisar
Mentor Graphics: * John Angulo
Zhen Mu
* Arpad Muranyi
Vladimir Dmitriev-Zdorov
Micron Technology: Randy Wolff
Justin Butterfield
NetLogic Microsystems: Ryan Couts
Nokia-Siemens Networks: Eckhard Lenski
QLogic Corp. James Zhou
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
Ray Anderson
The meeting was led by Arpad Muranyi
------------------------------------------------------------------------
Opens:
- Arpad: We will not meet Jan 29 since most of us will be at DesignCon
- Radek: Would like to discuss the latest dependency table BIRD
--------------------------
Call for patent disclosure:
- None
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Review of ARs:
- Fangyi, Ambrish, Walter to discuss merging their "Redriver" proposal with
BIRD 131.
- Fangyi: There has been no progress
- Walter believes one BIRD is generic while the other is AMI specific
- This makes it too difficult to merge them
- Arpad: Should we cancel this AR?
- Walter: Yes, we can cancel
-------------
New Discussion:
Interconnect task group report:
- Michael M: There has been no meeting since the last report
- We will continue discussion of tying AMI analog with interconnect proposals
- The next meeting will be tomorrow
- Walter: I sent a presentation in Dec reviewing that topic
- It was an email sent Dec 18
Arpad showed a presentation Analog Modeling Discussion:
- slide 2:
- Arpad: Our discussions have been going in circles
- We have too many BIRDs
- Some conceptual questions must be answered
- slide 3:
- Arpad described classic IBIS I/V behavior with regard to voltage
- Arpad: It handles only two "on" states
- Walter: Our fundamental differences are on three points shown here
- Everything here is true for [External Model] in IBIS 4.1 on, but not for
anything else
- slide 4:
- Arpad: Current flows from either of two supply nodes
- There is no direct transfer function from logic input to output
- The input stimulus is really a selector
- High and low states can have different impedance
- slide 5:
- Arpad: [Driver Schedule] describes events, the EDA tool handles the
transition
- slide 7:
- Arpad: LTI models such as s-params almost could be used directly
- But the spec says the impulse response has to be convolved
- slide 8:
- Arpad: This is the regular flow
- slide 9:
- Arpad: The alternate flow has the combined channel between the GetWaves
- Walter described the process differences
- slide 10:
- Arpad: The TX GetWave input stimulus is ideal, except maybe adjusted for
V=0 timing
- The output is semi-digital
- Walter: In this case only because the FFE is ideal
- slide 11:
- Arpad: For this flow the TX GetWave input has to be analog (semi-digital)
- The RX output is 1, 0, or X
- None of this is stated in IBIS 5.1
- Walter: There are many issues with this
- slide 12:
- Arpad: BIRD 116 proposes something similar, except a D-to-A is added
- slide 14:
- Arpad: These possible changes to [Model] may be too complicated
- slide 15:
- Arpad: Do we really need supply terminals?
- slide 16:
- Arpad: [Algorithmic Model] is always differential, but [Model] is single
ended
- It could not be used for single ended simulations
- slide 17:
- Arpad: There are many issue using [Model] for AMI
- We need a new model keyword for AMI
slide 4:
- Walter: We should focus on only Pullup and PullDown curves
- AMI assumes they are linear
- Also we can only measure in high and low states
- But the K(t) functions simulate intermediate states
- With SerDes the devices really just change current flows
- A SerDes can have many states, not just two
- It can be represented with Pullup and PullDown coefficients
- The Pullup/PullDown impedance doesn't matter because they are used
differentially
- The total impedance remains the same
- The control logic was implemented the way push-pull drivers typically
worked
- But nothing in IBIS forces it to be that way
- This is why using the IBIS buffer for the analog model is a problem
- Radek: That ignores some items in the IBIS spec
- An s-param block can't have DC sources
- I agree with Arpad
- Walter: The TX and RX models, especially above 6GHz, are s4p models
- We can do a better job describing how to generate those
- Arpad: What is used for the control input
- Walter: Effectively the GetWave output
- Radek: IBIS did not specify this well enough
- David: It was described in terms of mathematics
- We are changing the value of PUref and PDref
- The FIR output gives these values
- Michael M: Would like to hear how others are interpreting the spec
- It doesn't have to be digital vs. analog, it can be seen as real numbers
- David: It is the reference that changes, with UI granularity
- Michael M: We may need new model keywords to handle this right
- David: This also means clock-to-out for IBIS models is meaningless
- Walter: Timing is always done with standard loads
- IBIS says nothing about clock-to-out
- Values change in UI increments only with a "nice" FFE
- I have been modifying the Ramp boxes, not the PU reference
- Arpad: That relates to the idea that these are just real numbers
- slide 12:
- Arpad: The TX analog model input supplies power, so PU reference does not
- Walter: The diagram here doesn't quite work because it doesn't show
correct s-param connection to the differential driver
Michael M: We need a BIRD to address this
- Arpad: First we must settle our differences, whether a new keyword is needed
- David: We probably need to discuss the flows again to test assumptions
- Michael M: We need to see if people adhere to flow understanding A, B, or
even C
- A majority vote would not work well
- Arpad: We might need to settle Walter's assertion about pre-4.0 IBIS
- David: That may be going too far back
- Walter: We just need to be able to describe the analog model as s4p
- Arpad: Where is it connected?
- Walter: To the output of the logic block
- Arpad: We still need to determine the logic voltage level
- Walter: A document will be presented on that
- David: Each EDA vendor should present on how they handle TX GetWave
- Fangyi: We would have to get internal approval for that
-------------
Next meeting: 15 Jan 2013 12:00pm PT
Next agenda:
1) Task list item discussions
-------------
IBIS Interconnect SPICE Wish List:
1) Simulator directives
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