IBIS Macromodel Task Group

Meeting date: 14 December 2010

Members (asterisk for those attending):
Agilent:                    * Fangyi Rao
                            * Radek Biernacki
Ansoft:                       Chris Herrick
                              Danil Kirsanov
Ansys:                      * Samuel Mertens
                            * Dan Dvorjak
                              Deepak Ramaswamy
                            * Jianhua Gu
Cadence Design Systems:       Terry Jernberg
                            * Ambrish Varma
Celsionix:                    Kellee Crisafulli
Cisco Systems:              * Mike LaBonte
                              Stephen Scearce
			      Ashwin Vasudevan
Ericsson:                   * Anders Ekholm
IBM:                          Greg Edlund
Intel:                      * Michael Mirmak
LSI Logic:                    Wenyi Jin
Mentor Graphics:            * John Angulo
                              Vladimir Dmitriev-Zdorov
                              Zhen Mu
                            * Arpad Muranyi
Micron Technology:            Randy Wolff
Nokia-Siemens Networks:     * Eckhard Lenski
Sigrity:                      Brad Brim
                              Kumar Keshavan
                              Ken Willis
SiSoft:                     * Walter Katz
                              Mike Steinberger
                            * Todd Westerhoff
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:

- Arpad: We will next meet Dec 21 and Jan 4
  - Ambrish and Radek can not join

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Call for patent disclosure:

- none

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Review of ARs:

- Arpad update Versions BIRD
  - Done

- Arpad update Typos BIRD
  - Done

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New Discussion:

Introduction of Jianhua Gu:
- Working on AMI at Ansys

Version BIRD discussion:
- Arpad showed the latest draft
- Arpad: There was a comment that an AMI file should not have higher version
  than the referencing IBIS
- Bob: Any version should be allowed
  - That is why we want a separate Version keyword
- Radek: The parser may handle the IBIS version but not the AMI
- Arpad: Then the IBIS file should be updated
- Radek: It can take a while to adopt new parsers
- Walter: We are spending too much time on this
- Mike: Can AMI_Version be IBIS_Version?
- Bob: This is an AMI file, not an IBIS file
- Arpad: The AMI spec could someday be separate
- Arpad: There was a suggestion that no AMI_Version means 5.0
- Bob: That is my interpretation
  - I would oppose that
- Radek: It should stay
- Bob motioned to vote to submit this BIRD
- Mike seconded the motion
- Roll call vote:
  Agilent:        yes
  Ansys:          yes
  Cadence:        yes
  Cisco:          yes
  Ericsson:       yes
  Intel:          yes
  Intel:          yes
  Mentor:         yes
  Nokia:          yes
  SiSoft:         yes
  Teraspeed:      yes
  TI:             yes
- The motion passed

AR: Walter submit BIRD to open forum
AR: Mike post BIRD to ATM website

Arpad showed the Defaults BIRD:
- Show how an "ffe" parameter converts to DLL string
  - Is the whole thing one parameter?
- Fangyi: Names could be concatenated to form a namespace
  - For example AMI_RootName.ffe would be one parameter
- Arpad: Anything InOut should be included in both In and Out strings
  - Reserved and Model_Specific will be removed
  - All others will be retained
- Bob: Usage and Type are not passed
- Arpad: These are not easy decisions
- Walter: We don't need to debate this here
- Ambrish: It be be just a recommendation, not a rule
- Walter: Each vendor could make their own recommendations

AR: Arpad update and distribute Defaults BIRD

Walter showed a BIRD 122 sample SPICE deck:
- This will handle both generic and BIRD 122 broadband models
- The sample does not include Touchstone files
- Colored text indicates what each part is used for
- Fangyi: It is always 50 ohms?
- Walter: That is common
- Fangyi: In theory I can re-normalize
- Radek: The termination should be defined separately
- Walter: I will modify the BIRD to reflect comments
  - Anyone else can make suggestions by email
- Bob: Is the s-param interchangeable with the parameterized circuit model?
- Walter: With enough precision you should get the same results
  - But the reverse doesn't work
- Fangyi: The Vt in the middle will not be in the s-param
- Arpad: All DC elements will be lost
- Scott: Unless you include Vt as a port
- Bob: Should the model be adjusted to the voltage?
- Arpad: Why such a small rise time in the PWL?
- Walter: When you have Touchstone the rise time is zero
  - The Touchstone contains the rise time
- Fangyi: Rise time can be excluded from the Touchstone
- Walter: You could write that up for me
- Bob: The rise time could be in the triangle buffers
- Walter: You could write that up for me
- Arpad: So Tr should be close to zero?
- Walter: Yes
- Bob: Why was S11 chosen as zero
- Walter: A V source from the algorithmic model drives it
  - Kumar calls it a high impedance interface
  - Nothing reflects back from the control input
- Scott: If S11 is zero, inside the model there is a terminator to ground
  - It is an isolation amp model
  - The AMI spec is explicit that it is high impedance, no termination to
    ground
- Walter: Kumar should be asked about that
- Scott: We need clear instruction on what is needed to stimulate the s-param
  - The transfer function depends on the ref impedance
- Radek: It is not the ref impedance
- Scott: We need to know what source impedance is required
- Arpad: The circuit shows V sources driving it
- Bob: Driver models are not meant to be cascaded
- Fangyi: Do vendors have to provide this in their s4p?
- Walter: The spec says those rows are not used
- Fangyi: If the s4p has it the S11 will show up
  - Changing S12 will change the result
- Radek: Agree
- Walter: It depends on the simulator
- Arpad: The question is what do we mean by "not used"?
- Walter: I can't answer that
  - Mike Steinberger may be able to help
- Radek: If there are S12 terms you will get a reflection
- Walter: It would be the same of you made S11 V0

Walter showed an email from Fangyi:
- Fangyi: The equation is at the bottom
- Bob: We have defined S12 as zero
  - The real voltage gain is a function of S11
- Todd: Is this because S11 can affect V1 and therefore V2?
- Fangyi: No
  - If V1 was fixed V2 would still be affected by S11
- Bob: The defaults should be zero for series impedances and
  infinity for impedances to ground.

AR: Walter send example SPICE deck to Mike for posting

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Next meeting: 21 December 2010 12:00pm PT

Next agenda:
1) BIRD 121-124 discussions

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IBIS Interconnect SPICE Wish List:

1) Simulator directives

