IBIS Macromodel Task Group

Meeting date: 04 June 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 Rafat
                              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

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Opens:

- Arpad: Anyone willing to volunteer to take minutes? 
- Todd volunteered

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Call for patent disclosure:

- None

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Review of ARs:

- None

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New Discussion:

Interconnect update:
- Mike M. was not present, Arpad stated that EMD and BIRD 161 are being discussed.


BIRD 156 Discussion:
- Arpad: Still looking for closure based on last week's email
  - Does Rx sensitivity get used in the decision process?
- Todd: Proposal is to use Rx_Receiver_Sensitivity as a hysteresis threshold
  - The signal has to go beyond to switch.
- Arpad: Then the BIRD needs to include text to describe this?
- Todd: Yes.
- Ambrish: How is this used in the regular flow?
- Fangyi: The simulator doesn't make a decision in the regular flow.
- Ambrish: Why can't the model create the waveform for TX Getwave?
  - Why does the simulator have to sample at all?
- Fangyi: This BIRD describes a retimer flow that requires the simulator to sample the waveform for retimers.
- Ambrish: There should be text in the BIRD that describes how to model a retimer as a redriver.
- Todd: That is a cookbook issue.
- Fangyi: Agreed.

- Fangyi: Can we still modify the BIRD text and vote on this for IBIS 6.0?
- Arpad: We can make some changes, it depends on how complicated the changes get.
- Radek: Even if the changes are larger than usual, we should be able to vote separately on accepting the changes.
- Fangyi: I expect that the changes won't be more than a few sentences.
- Arpad: Let's sort these changes out via email before Friday's meeting and have a
  clean revised version ready to show in the meeting.

AR: Fangyi to get clarification of retimer flow ready for Friday.

- Walter: SiSoft believes that voltage noise (Rx_Noise) associated with redriver
  devices can be modeled reliably and accurately.
  - We understand that standardization discussions will require more time
    than is available before the IBIS 6.0 specification closes.
  - We therefore agree with BIRD 156 as written, with the understanding that we can
    introduce and discuss a subsequent BIRD associating Rx_Noise with redrivers
    after IBIS 6.0 has been approved.


BIRD 158 Discussion:

- Radek: The common mode issue was set aside to talk about impulse responses.
  - Common mode can still use further clarification.
- Walter: On the impulse response issue, legacy (non-Touchstone) models have a
  unit step control input.
- BIRD 158 models still have a unit input, TX/RX gain can be represented either with a scaling
  element before/after the Touchstone models or within the S-parameter block itself.
- Arpad: Legacy models have input voltages that are well understood.
  - But we need to be clear about where voltage scaling occurs for Touchstone data.
  - Is this done by the stimulus sources or in the Touchstone data?
  - We also need to be clear about initial conditions.
  - For instance, what is the 0 condition for Voh/Vol?
- Radek: Step response is used to determine the impulse response.
  - If the initial conditions for the step response are correct, the resulting impulse response will be correct.
- Fangyi: If everything is linear, the initial conditions don't matter.
- Bob: The amplitude of the output is determined by the interaction between Tx_V, Tx_R and the S-parameter matrix.
  - The model maker needs to make sure the model is developed so all the pieces work together.
  - They can develop the model to use a unit step voltage if they want to.
- Todd: That is correct.
- Arpad: Is IBIS-ATM expected to make a recommendation on how these BIRDs should be voted for in Friday's meeting?
- Bob: Not necessarily.

- Radek: Do we need Voh/Vol on the transmitter?
- Walter: Yes, to ensure proper biasing for the RX
- Radek: The LTI approximation still applies, though.
  - You have assumed the whole network is LTI.
- Todd: Yes, sometimes devices have limited areas of linear behavior and it's
  important to stay within that.

- Ambrish: Do we need BIRD 158 at all?
  - Can't people just use BIRD 160?
- Todd: BIRD 158 is a way to use S-parameters for the analog models using less text than BIRD 160
- Radek: That's true. BIRD 158 models are simpler.
- Ambrish: How confident are we that this syntax won't change in the future?
- Todd: On-die syntax hasn't changed in the last 4 years except for Tx_V and Tx_R, which were
  added to make the switch between unilateral and reciprocal S-parameter data simpler.


BIRD 154 Discussion:

- Arpad: Are there any outstanding issues or have the objections been resolved?
- Bob: Yes, they are resolved.
  - It just requires that the parser handle the new syntax.


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IBIS Interconnect SPICE Wish List:

1) Simulator directives
