IBIS Macromodel Task Group

Meeting date: 10 March 2015

Members (asterisk for those attending):
Altera:                       David Banas
ANSYS:                      * Dan Dvorscak
                            * Curtis Clark
Avago (LSI)                   Xingdong Dai
Cadence Design Systems:     * Ambrish Varma
                              Brad Brim
                              Kumar Keshavan
                              Ken Willis
Ericsson:                     Anders Ekholm
IBM                           Steve Parker
Intel:                      * Michael Mirmak
Keysight Technologies:      * Fangyi Rao
                            * Radek Biernacki
			    * Nicholas Tzou
Maxim Integrated Products:    Hassan Rafat
Mentor Graphics:              John Angulo
                            * Arpad Muranyi
Micron Technology:          * Randy Wolff
                              Justin Butterfield
QLogic Corp.                  James Zhou
                              Andy Joy
eASIC                         Marc Kowalski
SiSoft:                       Walter Katz
                              Todd Westerhoff
                            * Mike LaBonte
Synopsys                      Rita Horner
Teraspeed Consulting Group:   Scott McMorrow
Teraspeed Labs:             * Bob Ross

(Note: Agilent has changed to Keysight)

The meeting was led by Arpad Muranyi.

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Opens:

- Bob: I have a question to ask.

- Nicholas Tzou introduced himself. He is working on AMI models for Keysight.

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Call for patent disclosure:

- None


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Review of ARs:

- Michael M send AMI Direction presentation to Mike L for posting
  - Done but not posted yet.

- Randy send whiteboard circuit diagram to Mike for posting.
  - Done.

- Walter and Randy produce C_comp BIRD.
  - Randy: Some progress, but we need to resolve issues about parameters.

- Arpad to review IBIS specification for min max issues.
  - In progress.


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New Discussion:

Question about BIRD 155.2

- Bob: This adds a new Usage "Dep".
  - Does Resolve_Exists have to be True for this to be legal?
  - If not then Dep would be interpreted as Out when it is False.
- Radek: The editorial committee might handle this.
- Bob: Alternatively Dep might be illegal if Resolve_Exists is not True.
- Mike L: I would prefer that.
  - A Dep is suspicious if there is no Resolve_Exists.
- Fangyi: Not sure if AMI_Init uses this.

- Bob: Should the redriver flow be resolved before this is approved?
- Arpad: Walter found a flaw, that should be removed.
- Fangyi: It's only a problem when the RX has no AMI_GetWave.
  - The flow does not mention the new parameter.
- Bob: Not sure if the draft BIRD has a Reserved_Parameter.
- Radek: It is likely to be incomplete.
- Arpad: Walter's point was that it doesn't address the filtering
  in the first channel passing on to the second channel.
- Radek: There is a simpler way to address that.
- Arpad: Should that be done for the next IBIS release?
  - An editorial committee is being formed.
  - We have 9 approved BIRDs.

- Radek: The redriver flow BIRD is posted as 166.
- Arpad: It is not yet approved. Should it be in the next IBIS?
- Fangyi: It is not that important.
  - There are better solutions.
- Bob: It has no Reserved_Parameters.
- Fangyi: It has a parameter, but the flow doesn't use it.
- Arpad: If there is a better way that should be worked on.
  - Should there be a new BIRD if it can't be worked out with Walter?
- Fangyi: I sent feedback to Walter but haven't heard back.
  - I could explain my thinking.
- Arpad: The action item has existed for months.
- Radek: A competing BIRD might be good.



AMI Directionality:

- Michael M: We may not have had enough discussion on this.
  - There has not been much offline feedback.


Advance C_comp:

- Randy showed a figure drawn after the last meeting.
- Randy: The proposal is to add a new node to the C_comp model.
  where an arrow is shown.
  - The input buffer is actually somewhat isolated from the pad.
- Arpad: Are the buffer triangles independent?
  - Do they each have C_comp?
- Randy: They are circuit elements, not IBIS buffers.
- Radek: The whole circuit is present at all times?
- Randy: Yes.
- Radek: This is dissection a pin into separate in and out portions.
- Randy: Currently we can only look at the pad.
- Arpad: Would this be in the [Model] keyword?
- Randy: It would be part of the new C_comp proposal.
  - We have Si_Location and Timing_Location, this could be similar.
- Bob: C_comp won't solve the problem without having driver and receiver modes.
  - This is not like location.
- Arpad: Where are the clamps?
- Randy: They are at the A_signal, the pad.
- Arpad: The bottom buffer triangle is just a measurement point.
- Randy: Right.
  - It could be replaced with another symbol.
- Bob: Large RC isolates the receiver clamps.
- Arpad: Only Vinl Vinh are at the receiver.
- Randy: This is a node of interest for signal quality.
- Arpad: This could be done easily if there is no second [Model*] keyword.


- Michael M showed IBIS-AMI and Direction Indication.
- Michael M: This is about models looking forward.
  - Chapter 10 has something about single ended model support.
- slide 5:
  - Michael M:
    - The original proposal was to add two Reserved_Parameters.
    - IBIS Model_type should correspond to AMI_Model_Type.
    - Model_Direction is the state at any time.
    - The user controls direction for any given simulation.
    - Do we want to enable/disable buffers to be I/O?
    - Or do we want to limit each buffer to one direction.
  - Arpad: There should be no limitation.
  - Fangyi: I would prefer separate models.
    - Walter brought that up.
  - Michael M: Radek brought it up earlier.
  - Radek: It's hard to say what is preferable for the model maker.
  - Ambrish: We can surely have separate .ami files.
  - Arpad: Could there be multiple root names?
  - Bob: Only one root name can have Reserved_Parameters.
  - Michael M: There should be multiple .ami files with associated roots.
    - We might end up rewriting much of the specification for this.
  - Arpad: How do you give 2 AMI files for one DLL?
  - Bob: They can be on separate lines.
    - One would be for the TX model and one for the RX model.
- slide 8
  - Michael M: This shows that.
    - We used to argue against restricting to one AMI file.
    - Checking would have to be enforced.
    - Option 2 permits multiple [Algorithmic Model] entries.
      - This would have a Direction keyword.
      - There could be Direction "I/O".
  - Arpad: Is the single DLL the only technical hurdle?
  - Michael M: That would resolve how many AMI files there are.
    - There might be other consistency issues.
  - Arpad: What if there is a single DLL?
    - For single DLLs a Direction parameter would have to be passed in.
  - Arpad: We should fix those issues if they are all that holds it back.
  - Ambrish: I don't think there are serious issues.
  - Fangyi: Why not make it simple?
  - Mike: The complication is only for EDA tools.
  - Fangyi: It is about making the specification simpler.
  - Arpad: The number of files on disk would be reduced.
  - Radek: It is a complication.
  - Michael M: It depends on where the adjudication is handled.

- Michael M: I can't proceed until this is resolved.
  - Do we allow a single DLL for both TX and RX?
- Arpad: We should all answer this.
- Michael M: I may make a motion at some point.
- Arpad: There should be an email.

AR: Michael M send list email about directionality issues.


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Next meeting: 17 Mar 2015 12:00pm PT
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IBIS Interconnect SPICE Wish List:

1) Simulator directives
