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IBIS INTERCONNECT TASK GROUP
http://www.ibis.org/interconnect_wip/
Mailing list: ibis-interconnect@freelists.org
Archives at http://www.freelists.org/archive/ibis-interconn/
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Attendees from April 22, 2020 Meeting (* means attended at least using audio)
ANSYS Curtis Clark*
Intel Corp. Michael Mirmak*
Ifiok Umoh
Eric Edwards*
Keysight Technologies Radek Biernacki
Mentor, A Siemens Business Arpad Muranyi*
Micron Technology Justin Butterfield*
Randy Wolff*
SiSoft Walter Katz*
Mike LaBonte
Teraspeed Labs Bob Ross*
Michael Mirmak convened the meeting. No patents were declared.
Justin Butterfield took minutes.
Eric Edwards from Intel introduced himself as a user of IBIS working on
customer simulations.
Review of Minutes:
- Michael called for review of the minutes from the April 15, 2020 meeting.
Randy Wolff moved to approve the minutes. Curtis Clark seconded. The
minutes were approved without objection.
Review of ARs:
- Randy to organize the examples in a word document.
- Randy reported this is done, he noted this is copied into the draft.
- Bob Ross to send out a draft2 of the EMD parts rewrite.
- Michael reported this is done.
Opens:
- Michael asked if the IBIS 7.0 Interconnect example is posted on the website.
Randy replied this is posted on the Interconnect page.
Revised IBIS 7.0 Interconnect Examples:
Randy noted the IBIS parser ibischk7 was released and the Interconnect examples
showed a few issues with errors and warnings in the parser. He has resolved
these issues in the model examples. One of the issues was a typo. The other
issues related to how the VDDQ net is laid out on this package where it has
separate routing on the left and right sides, which results in two separate
nets in the package model. He changed the package models to short these nets.
Randy noted VPP has a similar problem, and he created a [Bus Label] for it.
Arpad Muranyi asked if there is a syntax limitation. Randy commented there are
simple ways to fix these issues. Arpad asked if there could be situations
where this cannot be done and if there is a change that can be done to the
syntax. Randy replied we have a rule that prevents this. Bob commented there
are ways of shorting terminals, but these can create issues with the integrity
of the model. You cannot have overlapping or repeated terminal names to create
shorts. Randy noted there are ways of creating the package model to prevent
this. The Touchstone 2 example has two separate VDDQ terminals. Randy
re-simulated the S-parameter to short the two VDDQ nets. He noted the short
could be added in an IBIS-ISS wrapper as well.
Michael asked if the connections are arbitrary and if this is an issue with the
extraction tool. Randy replied it is better to make the choice to short or
merge the proper die and ball ports before the extraction. Merging everything
together allows you to connect with a signal_name rather than by pin.
Arpad asked if there could be an S-parameter received by someone else that
could have this issue. He also asked about the merging of the ports and if
this can done for cascading models as well. Randy replied it is possible to
merge the two. Bob asked if there are mathematical ways to do this. Arpad
stated this could have issues if the models have different frequency points.
Michael commented the errors in the parser would give clues to the issues.
Arpad agreed and noted an IBIS-ISS wrapper could resolve these issues.
Bob asked if this new version passes the parser with no errors or warnings.
Randy replied it does. Michael asked if there were any cautions. Randy will
rerun the ibischk7 parser on the Interconnect examples with the cation flag
enabled and report back [AR].
Michael asked if this will be discussed at the IBIS Open Forum. Randy
responded he can bring this up. Michael asked if the models are complete with
the IBIS-ISS and Touchstone files. Randy stated, yes, all the necessary files
are included, and the Touchstone 2 file is with a .ts extension.
EMD Draft Review:
Arpad noted there were two emd_parts_draft3 documents sent out and asked if
these are the same. Bob stated these are the same. The Usage Rules section,
where the format is described, is updated; although, he has not updated the
names of the columns yet. The example includes two cases of NA NA. There is
an additional paragraph that talks about this case, where the IBIS component
does not exist. An example was added with an NC IBIS model, and an additional
paragraph addresses the NC case with partial IBIS files, which describe only
the digital signals. The final paragraph is regarding the notes section
recommending documentation for the unknown parts. Randy stated he reviewed
this draft and it looks good. Bob plans to copy and paste this into the EMD
draft.
Bob sent out a draft with Randy's example, but the example has a syntax issue.
He has also added rules which need to be reviewed.
Michael noted we need to paste the EMD Parts text into the EMD draft. Bob will
add the EMD Parts section in the EMD draft 7 [AR].
Bob noted, in EMD draft 6, he copied the language for POWER, GND, and NC from
section 3.2. He added a note for NC, where it can be used for non-digital
signals that cannot be described by IBIS. Bob added Randy's figures in a new
section 13.6 with the examples. He reviewed this section. The examples and
figures are now tied together with the text. He noted we may have the same
subcircuit for different purposes. Walter Katz noted it could be a tricky
problem for termination resistors between differential nets. Bob stated we
would have to think about this, if we can use the Series models for this.
Arpad thought the Series model would work for this.
Next Meeting:
The next meeting will be April 29.
Randy moved to adjourn. Arpad seconded. The meeting adjourned without
objection.
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Bin List:
EMD Comments to be Resolved:
(See BIRD202.1 tracking spreadsheet)
IBIS-ISS Parser:
- IBIS-ISS parser scope document