[ibis-macro] Minutes from the 19 Mar 2013 ibis-atm meeting

  • From: Mike LaBonte <mike@xxxxxxxxxxx>
  • To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
  • Date: Tue, 19 Mar 2013 16:29:15 -0400

Minutes from the 19 Mar 2013 ibis-atm meeting are attached.

IBIS Macromodel Task Group

Meeting date: 19 Mar 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


- Walter: Would like to discuss BIRD adoption plan for IBIS 6.0

Call for patent disclosure:

- None

Review of ARs:

- Walter write new BIRD for repeater/retimer pin keywords
  - In progress

- Arpad try to apply BIRD 158 shortcut language to his BIRDs 116-118
  - In progress

New Discussion:

Analog BIRDs:
- Arpad showed a list of BIRDs that have been converted to the new BIRD format
- Arpad: The content has not changed.
  - This may be easier once my AR has been done

- Arpad showed presentation "Analog BIRD Overview":
- slide 3:
  - Arpad: The first four BIRDs would have to be voted in to implement the 
    - The other two are optional.

- Arpad: A BIRD-like document has been uploaded but not yet announced
  - This combines four BIRDs
  - We should read it
  - It could be submitted as an official BIRD if that helps
- Ambrish motioned to submit the combined BIRD incorporating BIRDs 
- Bob seconded
- There were no objections
- Bob: We should look at them first
  - I have some technical comments, one about parameters and the other about 
parsing logic
- Arpad: We can have those discussions next week

Arpad showed presentation BIRD 159 Discussion:
- slide 2:
  - Arpad: There was a question about the receiver threshold voltage
    - Mike Steinberger and Walter had replied about this
    - The IBIS specification has clear language
  - Walter: We should decide that the waveform is centered around 0V
  - Michael M: What is the reference location?
  - Arpad: Let's get to questions at the end
- slide 3:
  - Arpad: The specification says there is a single waveform
    - It does not assume it is differential
- slide 4:
  - Arpad: On page 123 the interface is said to be differential
- slide 5:
  - Arpad: How do we resolve this?

- Michael M: Any common mode effect is outside the scope of AMI
- Walter: Agree
- Michael M: Most flows are statistical
  - It still needs to be known if the common mode bias is correct
  - AMI models are not helpful for that
- David: So a DC bias will not be modeled correctly?
- Todd: We are only saying the network characterization produces a
  differential waveform
  - Nothing is said about common mode
- Walter: The impulse response is based on the differential output
  - This uses the TX analog model
- David: The channel has even and odd mode propagation
  - The RX input will never know about common mode
  - The question is if the differential behavior of the TX can be affected
- Arpad: We pass to the algorithmic model an impulse response, not a waveform
- Ambrish: GetWave receives a waveform
- Arpad: It says "centered nominally around zero volts"
- Walter: A stream of ones will not be centered around zero
  - We transmit only the differential part of the waveform
- Todd: David was asking if the mode conversions affect the differential 
- David: Michael asked if loading that is not nominal changes the result
  - Can that happen with a Ramp-only TX?
- Todd: Yes
- Arpad: It can if the differential buffer uses two different models
- Todd: Non-linear curves can create those effects
- David: So Ramp-only models do not preclude us from catching those effects
- Walter: Edge timing skews can cause this effect too
  - EDA tools with proper analog models will model it
- Arpad: The algorithmic model will not care about non-differential effects
  - I thought we were supporting both single ended and differential models
- Walter: I could create an S2P just to represent the differential part of a 
  - The intent was not to do single ended DDR4
  - AMI does not really support it
- Arpad: Are we restricting ourselves unnecessarily?
- Walter: We can fix it in the future if the need arises
  - At that point an RX receiver threshold fix would be needed
- Todd: The specification we have now is about differential
- Arpad: What about the page 123 language?
- Radek: That should be eliminated
- David: The model only knows it is receiving a series of numbers
- Todd: It won't be right if the channel has not been handled correctly
- Walter: I think the answer to "Is it clear to everyone" is no
  - This BIRD proposal should be withdrawn
- Bob: The assumption of centering on 0V is still a problem
- Walter moved to recommend voting down BIRD 159
- David seconded
- No one objected

- David: Does Michael have any thoughts about his questions?
- Michael M: Statistical analysis does not account for common mode
  - That's OK, but it needs to be clearly documented

Walter: We should discuss a BIRD plan in a future meeting
- Michael M: Agree, we have 18 or 19 open BIRDs now
  - Members should submit their preferred lists
- Michael M: Speaking as an Intel employee for a moment, a repeater 
  is very important
- Walter: I will send a spreadsheet

Next meeting: 26 Mar 2013 12:00pm PT

Next agenda:
1) Task list item discussions

IBIS Interconnect SPICE Wish List:

1) Simulator directives

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