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IBIS INTERCONNECT TASK GROUP
Mailing list: ibis-interconnect@freelists.org
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Attendees from March 6, 2024 Meeting (* means attended at least using audio)
ANSYS Curtis Clark
Broadcom James Church
Intel Corp. Michael Mirmak*
Michael Brownell
Keysight Technologies Ming Yan
Marvell Steve Parker
MathWorks Walter Katz*
Micron Technology Justin Butterfield
Siemens EDA Weston Beal*, Arpad Muranyi*, Randy Wolff*
ST Microelectronics Aurora Sanna
Synopsys Ted Mido, Edna Moreno
Teraspeed Labs Bob Ross
University of Illinois Jose Schutt-Aine
Zuken USA Lance Wang*
Michael Mirmak called the meeting to order. No patents were declared.
Michael reviewed the minutes of the February 21 meeting. Lance Wang
moved to approve the minutes; Randy Wolff seconded. No objections
were raised and the minutes were approved.
Michael reviewed the minutes of the February 28 meeting. Arpad Muranyi
moved to approve the minutes; Randy seconded. No objections were raised
and the minutes were approved.
During the AR review, Michael noted that his AR to contact the IBIS
Quality Task Group regarding parser APIs has been closed - he presented
last week to the Task Group. Michael noted that he still has an open AR
to review the IEEE 370 text for sampling information. All ARs to other
people have been closed.
During Opens, Lance Wang noted that he needed to leave early.
Walter Katz presented regarding his port-mapping proposal in comparison
with Arpad's. The latest slides included fixes to typographical errors
but there were no additional updates. An additional slide was placed at
the end to show examples with references being removed. Walter noted that
all agree the proposals are equivalent.
In the notation, "-" means negative terminal; "+" means positive terminal.
Some discussion ensued on the meaning of "reference" vs. "- terminal".
Michael asked whether Arpad's format allows +, - and a separate reference terminal.
Weston Beal added that the order of +, - terminals affects phase in complex number
calculations.
Michael identified four possible referencing cases:
- local voltage references for every node
- ideal node zero everywhere
- ideal node zero in a single location
- differential approach (collapses into one of the other three)
Walter replied that the reference 0 node doesn't exist; the actual reference
node is a point as close as possible to the physical measurement point.
Weston noted that the physical points are well-defined here. For industry, the
problem is, in 3D models, bad port definitions.
Michael asked whether one can use ideal node 0 in both format proposals. Weston
replied that, in the source of the s-parameters, there is no node zero; it's a
mathematical construct.
Weston added that we have no knowledge of where the measurement point is, so we
tie it to node zero.
Walter replied that we can have the reference point have a voltage with respect
to another point.
Arpad proposed imagining a single buffer with 3 terminals: Vdd, signal, Vss.
Does this system have 6 or 4 ports?
Walter replied that you should be measuring at Vss; additional research and
discussion is required on referencing.
Weston suggested that referencing discussions are a "mink hole".
Arpad proposed creating a list of criteria, e.g. machine-readable, human-readable, etc.
needed for the format. Walter replied that are both machine-readable/writable. The
question is which one is human-readable and documentable.
Weston stated the he likes personally to look at data, but lots of people don't.
With that, a table-based format seems just as good.
Walter moved the question to adopt either a table-based (Walter) or keyword-driven
(Arpad) format.
As a point of order, Arpad noted that each field in his format is optional once you
get past the + terminal (all are assumed to use node zero if not specified).
Weston suggested that the formats need an N/A equivalent placeholder. Walter agreed.
The people who care about the format are in this meeting.
Weston seconded the motion. Walter abstains to avoid writing the TSIRD.
Randy asked whether the voting would be conducted by organization or by individual,
noting the corporate affiliations in the meeting.
Michael replied that his understanding was that the voting was by individual, but
added that the team has rarely conducted votes by anything other than acclimation
in the past.
Randy requested additional information on "PinDef" in Walter's proposal. Walter noted
that he personally prefers "PinDef" to "group". PinDef is followed by a physical list of pins.
Randy suggested that the team could propose a vote, in case of a tie, to the IBIS Open Forum
on March 29 (Walter will not available March 8, and would need time to prepare slides).
Walter added that customers want enhancements as follows:
1) data to create a schematic symbol; usually two sides, with 1:1 input-to-output connections,
but if you have a multi-drop net, the symbol will get complicated. Walter showed a [Schematic Symbol]
keyword with division of ports.
2) information on the measurements themselves; customers use Touchstone as part of the process of
making the measurements. In this usage, some data is simulated, some measured; want some information
about a port or matrix element added.
Arpad stated that his proposed format easily adds this through keywords; columns have pre-defined
meaning and adding data may be difficult.
Walter suggested Sij_Status as an option; this would be part of the PinDef keyword.
The vote was taken as follows:
Weston: table format
Walter: abstained
Michael: keyword format, noting this was not a strong preference
Arpad: keyword format
Randy: abstained
Arpad asked about next steps. Michael stated that this would be deciding who writes the TSIRD.
He added that this effort may push finalizing the options/[Reference] TSIRD out of consideration
for some time due to the work involved.
The team shifted to discussing the options/[Reference] TSIRD. Arpad reviewed draft 3, noting that
the only change to is to clarify the rule regarding the option line and reference. A minor
clarification was added on whether Noise Data by itself was still permitted as opposed to Network
Data and Noise Data together.
Michael asked whether a Karnaugh map would still be needed to identify legal combinations. Weston
replied that a truth table is what we need. However, the lack of a table does not prevent TSIRD
approval and forwarding to the IBIS Open Forum (the table would mostly be for the parser developer).
Randy noted that, in the Solution Requirements at the top of the text, requirement 2 should be in
the summary of proposed changes. He also noted that [Reference] being optional is mentioned twice in
the text.
Randy to work with Arpad to revise the text and provide to the IBIS Interconnect Task Group. The
changes and final version will be reviewed in the next meeting.
Arpad moved to adjourn; Weston seconded. The meeting adjourned.
The next meeting will take place on March 13, 2024.
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Bin List:
1) [Complete draft Touchstone document separating version 1.0 and 2.0 into their own chapters] - REMOVED
2) Create structures to encapsulate Touchstone 1.0 data in Touchstone 2+ specifications - TABLED
3) Complete draft Touchstone 2.0 document containing TSIRD3 and TSIRD4 draft (Muranyi) – COMPLETED
4) Complete pole-residue format BIRD draft (Muranyi) - COMPLETED
5) Complete port naming proposal (Katz)
6) Create alternatives to the Touchstone 1.0 option line before the "R" character - TABLED
7) Complete ISS-IRD 1 Draft - Enable Cascading of S-parameters Through W-element (Mirmak) - TABLED
8) Complete/revise Touchstone 3.0 draft outline (Mirmak) – dependent on several items above
Tabled ARs:
- Arpad to give an example of the physical connectivity needed for EMD automation.