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IBIS INTERCONNECT TASK GROUP
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Mailing list: ibis-interconnect@freelists.org 
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Attendees from May 25, 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 May 18, 2022 meeting.  Randy 
  displayed the minutes.  Randy noted the date of the meeting was not 
  correct.  Bob Ross motioned to approve the minutes with the date corrected.  
  Lance Wang seconded.  The minutes were approved without objection.


Review of ARs:
- Arpad Muranyi to give an example of the physical connectivity needed for EMD 
  automation [AR].
  - Randy suggested to keep this open.
  
- Walter to send the draft PLS document.
  - Done.


Opens:
- None.


Discussion:

PLS in Touchstone TSIRD Draft:
Arpad noted that he has not reviewed the PLS document from Walter yet.  Bob 
stated that we have to decided how to partition the PLS and port naming.  He 
suggested to have separate sections.  Randy asked if this means separate 
sections in the specification or in the Touchstone file.  Bob replied 
potentially both in the specification and in the file, but mostly, he is 
concerned with the specification for now.  We still need to decided how to 
structure the Touchstone files.

Arpad asked about the duplication of keywords in the specification.  Bob is in 
favor of having some duplication.  Arpad suggested to not duplicate the port 
naming.  Bob stated the port naming could be a separate section that can be 
used for both Touchstone and PLS data.  Randy stated each keyword is a new 
section.  Arpad commented some keywords would be duplicate, but he does not 
like that idea.  Bob noted we would not want to repeat keywords if the 
information should be the same.  Bob noted an additional section could be the 
header section, which could be common for PLS and Touchstone.  The port naming 
could be in the front of the file.  Randy noted the file can be read more 
easily if the PLS data is before the network data.

Arpad noted the biggest question is what to do with the option line.  We kept 
it in Touchstone 2 to help the EDA tools with backwards compatibility.  Randy 
noted you still have to down convert a Touchstone 2 file to use the file in a 
Touchstone 1 only tool.  Arpad commented, if we have the PLS data, it would 
have to be converted with a frequency sweep back to network data.  Bob stated 
the option line is not something we can remove from Touchstone, since there 
are too many tools that use it.  

Randy asked about the option line for the PLS data.  Bob suggested to keep the 
option line and network data as is.  Randy asked if any of the TSIRDs improve 
the network data.  Bob stated some of them do consider the network data and 
some would apply to PLS, but we would have to think about this.

Arpad suggested we could move the option line next to the network data and not 
have it for the PLS format.  Randy suggested we need to describe an order for 
the keywords.  Bob stated we need blocks of syntax.  We could have blocks of 
keywords for network data, PLS, port naming, and header information.  We would 
need to make the rules about the order of these sections and which ones are 
optional.  There could be upward compatibility issues if we are not careful 
with these rules.  

Bob asked if we can mix Touchstone versions with PLS.  Arpad replied they can 
support Touchstone 1 and Touchstone 2 conversions to PLS.  Bob noted this 
would be another rule if we wanted to enforce it.

Arpad asked if we want to complicate the Touchstone 3 specification by 
including the legacy features and related rules.  Bob suggested we should not 
deprecate the Touchstone 1 format that everyone uses.   Arpad asked about 
mixing versions for different sections.  Randy thought having different 
versions for each section would not work well.  If you add the Touchstone 3 
features, then it is a Touchstone 3 file.  Randy noted we do not do this in 
IBIS files.  Arpad noted the AMI and IBIS could be different versions.  Randy 
noted they are separate files.

Arpad asked, if we have the port naming and PLS data making the model a 
Touchstone 3 file, why do we need to keep the old features.  Randy replied 
that the tool parser should support all the Touchstone 3 features.  He noted 
the parser could down convert from Touchstone 3 to older versions.

Lance asked if we are considering keeping the PLS and network data in the same 
file.  Randy replied that we are considering this.  Lance asked if the data 
could be different between the two formats.  Randy replied that this would be 
an egregious model error, but he was not sure that it could be checked.  Bob 
stated we cannot check the content, but we can check the number of ports. 

Arpad asked if the down converter could move the port naming to comments.  
Randy and Bob agreed this would be a good idea.

Randy noted you cannot convert the Touchstone 2 to Touchstone 1 if you have 
the per-port reference impedance.  Bob agreed there are conversion 
limitations.  Randy commented that the option line could be handled to move 
between versions.

Randy commented the option line does not work well for the PLS data.  Bob 
suggested to block out groups of information in the syntax.  He stated it will 
complicate the rules to remove the option line.  Arpad noted that having the 
option line complicates the rules since we have duplications and would have to 
check both.  Randy suggested to write down some the rules to start looking at 
the issues.

Arpad noted, currently, we can have a discrepancy between the option line and 
the per-port reference impedance.  Randy asked if the per-port reference can 
support a single value.  Arpad replied all reference impedances must be 
listed.  Arpad noted we could have more complicated rules and options for 
defining the reference impedance.  He also suggested we should consider 
complex numbers in the Reference keyword.


Arpad motioned to adjourn.  Bob seconded.


Next Meeting:
The next meeting will be June 1.


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