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IBIS INTERCONNECT TASK GROUP
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Attendees from May 11, 2022 Meeting (* means attended at least using audio)

ANSYS                                Curtis Clark
Intel Corp.                          Michael Mirmak
                                     Michael Brownell
Keysight Technologies                Ming Yan						 
Marvell                              Steve Parker
MathWorks                            Walter Katz
Micron Technology                    Justin Butterfield*
                                     Randy Wolff*
Siemens EDA                          Arpad Muranyi*
ST Microelectronics                  Aurora Sanna
Teraspeed Labs                       Bob Ross*
University of Illinois               Jose Schutt-Aine
Zuken USA                            Lance Wang*


Randy Wolff convened the meeting.  No patents were declared. 
Justin Butterfield took minutes.

Review of Minutes:
- Randy called for review of the minutes from the April 27, 2022 meeting.  
  Randy displayed the minutes.  Lance Wang motioned to approve the 
  minutes.  Bob Ross seconded.  The minutes were approved without objection.


Review of ARs:
- Arpad to send out the pole/residue format draft.
  - Done.

- Arpad Muranyi to take a look at what will carry over from Touchstone 2.
  - Arpad reported he did not formally create a list, but he did make some 
    edits in the PLS draft 3 to consider this.

- Arpad to give an example of the physical connectivity needed for EMD 
  automation. 
  - Arpad asked what was the context of this.  Justin replied this was 
    regarding the minimum information needed in the port mapping to 
	automatically generate EMDs.  Arpad to asked to keep this open [AR].

- Randy to send out links to the C-PHY information from previous IBIS Summits.
  - Randy sent out the links.  Arpad asked if we should also take up C-PHY in 
    the ATM meeting.  He noted it would be interesting to look at the 
	multi-level signaling as well.  Randy agreed this would be a good topic.


Opens:
- None.


Discussion:

PLS in Touchstone TSIRD Draft:
Arpad shared the latest draft of the PLS document.  He has cleaned up the 
document by moving the comments from Vladimir Dmitriev-Zdorov to the reviewer 
comments.  He highlighted the areas where we need to make decisions.

Arpad stated the first highlighted section is about the existing option line, 
the existing [Number of Ports] keyword, and the existing [Reference] keyword.  
If we make changes, he would suggest to remove the option line.  It is 
limited, since it only allows one reference impedance, which can be 
confusing.  Randy noted some EDA tools support non-standard reference lines.

Arpad commented that Vladimir has said that units on the option line are not 
necessary.  Arpad asked if there is a Touchstone 2 keyword for this.  Randy 
replied there is not.  Bob stated, with the options line, there is a unit 
format which is consistent for S, Y, Z, H, and G-parameter formats.

Arpad noted the [Mixed Mode Order] keyword could be applied to the 
Pole_Residue data.  Randy noted the [Mixed Mode Order] keyword lets the EDA 
tool know the order of the ports for differential vs. single-ended ports.

Arpad noted he is proposing three new keywords for the poles and residues with 
options to specify each pole and residue or as common poles.

Arpad noted, for sparse matrix, the number of poles could be zero.

Arpad asked Vladimir about the H and G matrices.  Vladimir thought these could 
be represented in pole-residue format in theory, but he questioned the 
usefulness of this.  Vladimir also raised the question of A and B parameters.

Arpad noted we need to think about the name of the Number_of_Poles 
subparameter. 

Arpad stated, regarding the swathing, there could be passivity violations with 
this approach.  Vladimir did not see the usefulness of the swathing to reduce 
the file size.  Bob had proposed a swathing TSIRD, but he agreed it could have 
passivity issues.  Arpad could see the usefulness on highly regular 
structures, but the danger could be if the same approach is used for a more 
complex PCB.  Bob suggested that we should track Touchstone 3 with the 
features in the pole-residue proposal.  Arpad suggested the Sparse Matrix 
could be easily supported in pole-residue.  

The group discussed the pros and cons of having the data in the same file or 
in separate files.  Randy noted, since the structure is keyword based, the 
files could support both data formats or the PLS and Touchstone data 
individually.  

Arpad highlighted the problem with .sNp file extensions, where the same base 
filename could be overwritten when converted to PLS format.  This could be an 
issue if we have separate files.  Bob suggested to standardize on an 
extension.  Arpad noted you could have the number of ports in the extension 
for PLS, but he does not like this approach.  Bob said, if we support combined 
files, we would have to decide if want to standardize on the extension.

Arpad asked how he should proceed with this draft.  He asked if we should 
start editing the Touchstone specification or write a separate specification.  
Bob suggested to consider it as a separate specification, as it would be messy 
to edit the Touchstone specification.  We could have separate top-level syntax 
blocks.  Arpad noted the port naming is another issue.  Arpad suggested it 
would be simpler to add the PLS to Touchstone.  Randy was in favor of having a 
combined specification.  Since people are already very familiar with 
Touchstone, we can simply add PLS as a new feature.  Arpad asked if there was 
any special meaning to the Touchstone name.  Bob was not sure.  Bob was not 
opposed to combining the specifications.

Arpad asked what is the general style he should take with the PLS document.  
Should he follow the usual BIRD format suggesting various specific wording 
changes?  Should he add the keywords from Touchstone and make the changes for 
PLS?  Randy suggested to add the keywords from Touchstone and make the changes 
for PLS, then we can merge it with the Touchstone 2.  Arpad asked if he should 
consider Touchstone 1.  Randy suggested to only consider Touchstone 2.

Bob asked about a possible presentation for the European IBIS Summit.  Arpad 
replied he was thinking to take this draft and create some slides.  Bob agreed 
with this and suggested to comment that there are some issues.  Arpad will 
highlight some of the questions for the discussion.


Arpad motioned to adjourn.  Bob seconded.


Next Meeting:
The next meeting will be May 18.


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Bin List:
1. Touchstone 3
2. Pole-residue support for Touchstone
3. Port naming