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

  • From: Mike LaBonte <mike@xxxxxxxxxxx>
  • To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
  • Date: Tue, 19 Feb 2013 22:32:25 -0500

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

IBIS Macromodel Task Group

Meeting date: 19 Feb 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


- Arpad: I may not make it next week
  - Someone else could run the meeting

Call for patent disclosure:

- None

Review of ARs:

- Walter write new BIRD 122 replacement draft
  - Done

- Ambrish email reflector regarding BIRD 147 status
  - Ambrish: There is confusion over this, but working on it

New Discussion:

Interconnect Task Group report:
- There was no meeting

Arpad: Walter will introduce a new BIRD proposal and immediately table it
- Arpad showed new BIRD draft "Support PAM4 in AMI Modeling"
- Walter:
  - Mainly PAM4 has 4 signal levels
  - NRZ is also known as PAM2, but that is not commonly used
  - We should only have to tell the tool it is PAM4
- Arpad: PAM can have various signal level counts, could we just have a number?
- Walter: That is possible
- Arpad: Should this be in IBIS, not AMI?
- Walter: [Model] is very much dedicated to binary buffers
- Arpad: Should analog models be in IBIS or in AMI?
- Walter: PAM is tied to SerDes, therefore it should be AMI
- Bob: Should we wait for 802.3bj to be approved?
- Walter: That is well under way, but we can table until then
- Michael M: When will that be finalized?
- Walter: Probably a year
- Arpad: It would be best to spend our time on other BIRDs right now
- Arpad moved to table
- Walter seconded
- No one objected

Arpad showed BIRD draft "AMI Touchstonefile Analog Buffer Models"
- Walter: This uses the Tstonefile AMI parameter to call for an s4p on-die model
  - Circuit diagrams show the other elements required for TX and RX
  - Last week there was a question about whether we should specify how to
    generate the impulse response
- Radek: That was for legacy IBIS
- Walter: We could specify reference methods, not normative
  - An alternative would be to use the arithmetic recommended by James
  - I do not think either normative or reference methods could be described
- Todd: This is not related to BIRDs 116-188
- Arpad: There were some emails about this
  - Immediately after the summit we had a discussion and agreed to have this 
  - The other proposal is BIRDs 116-118
  - This proposal uses a template and solve the issue only for AMI
- Bob: The proposal did not mention [External Model]
  - This seems like it works only with [Model] does not interfere with 
[External Model]
  - I don't see conflict
- Arpad: At DesignCON I suggested we could have both proposals
  - They do not conflict
  - Walter said vendors are already doing this and models exist
- Ambrish: Is that good enough?
  - Can Walter's proposal be done with BIRDs 116-118?
- Walter: Yes, but a subckt and other unnecessary work is required
- Todd: We wrote the AMI file as though those BIRDs were in effect
- Ambrish: Does this replace BIRDs 116-118?
- Todd: No, we wrote it as though that ISS subckt existed, and just used the
  - There may be a disconnect because this is differential and [Model] is 
single ended

- Arpad: There is mention of subckts
- Michael M: Examples would help
- Todd explained this using the circuit diagrams
- Walter: Clarification: the subckt does not include the voltage supplies
- Todd: Once the circuit in IBIS declares parameters they can be used from AMI
  - We simply assumed the circuit existed
- Walter: We could wait for BIRD 116 to be approved, then add in the other stuff
  - That would be IBIS 6.0 compliant
  - Meanwhile we can do it this way and there is no illegal syntax
- Radek: We do not necessarily want it, but the parameters could become reserved
  - That would take precedence over the legacy IBIS model
- Ambrish: That would be mandating BIRD 122
- Todd: I agree with Radek, these parameters technically should be reserved
- Arpad: After BIRDs 116-118 are approved we might be required to have the 
actual circuits
- Bob: Bypassing BIRDs 116-188 makes sense
- Radek: It is also necessary that we cover how source impedances are treated
- Ambrish: That can be done with the circuits
- Radek: This shortcut is useful
- Todd: We all agreed to have this proposal
  - This is not to undermine BIRD 116
- Ambrish: We have gone from model specific to reserved, to just for discussion,
  to a real BIRD
- Walter: We can have both solutions
  - This does not preclude BIRD 116
  - The only question is whether to support the shortcut

- David: Walter said non-straight-line IV curves could not be used
- Walter: They can be used but there will be accuracy problems
- David: Do BIRDs 116-188 allow those non-straight-line features?
- Walter: Since IBIS-ISS is LTI, we will not have that problem
- Todd: You can't model non-linear with it
- Walter: With the AMS languages and SPICE you can

- Arpad: For this we would want reserved, for BIRDs 116-118 model specific
  - Other than that they are identical
  - I don't mind this interim solution
  - There are a few details we would have to go over
    - An analog simulator can't have zero time edges, etc.
- Todd: The time is "practically zero"
- David: Something is wrong if touchstone depends on how it is driven
- Todd: The output changes
  - Driving with a square wave then a ramp will have different outputs
- David: Is "close to zero" ramp the right approach?
- Todd: It is the best we have right now
- Walter: Impulse responses are all die to die s4ps, that is how they are
  doing it?
- Bob: We can:
  - Accept this
  - Accept BIRDs 116-118
  - Accept both
- Arpad: The other BIRDs could also be modified to include this
- Bob: The diff circuit might not be centered around zero
  - Only BIRDs 116-118 are general enough for that
- Walter: IBIS-ISS would not handle that either
  - IBIS-BSS could do non-LTI
  - BIRD 116 should wait for that
- Arpad: That would be an interim solution
- Ambrish: In what order should we discuss these?
- Radek: We should discuss both approaches
- Arpad: We should try adding the shortcut idea to BIRD 116
- Radek: There was a BIRD to add Touchstone as a language
  - But that would require specifying the termination conditions
  - There is nothing to be done here
- Bob: The press release referred to BIRDs 116-118 as though they are supported
  - Are those supported yet?
- Radek: No, but there would be no difficulty doing that

AR: Arpad try to add shortcut language to his BIRDs

Bob: About the PAM4 BIRD, Range would allow it to support any number of levels

Next meeting: 19 Feb 2013 12:00pm PT

Next agenda:
1) Task list item discussions

IBIS Interconnect SPICE Wish List:

1) Simulator directives

Other related posts:

  • » [ibis-macro] Minutes from the 19 Feb 2013 ibis-atm meeting - Mike LaBonte