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IBIS INTERCONNECT MODELING AD HOC TASK GROUP MEETING MINUTES AND AGENDA

http://www.eda.org/ibis/adhoc/interconnect/

Mailing list: ibis-interconn@freelists.org

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Next Meeting
January 30, 2008

               Telephone     Bridge   Passcode
              916-356-2663     2      986-2594

Agenda:
- Review of proposals to combine ICM and IBIS for package modeling
- IIRD9 status
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Minutes from January 23:

Attendees:
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(* denotes present)
Agilent                    - Radek Biernacki*, John Moore
Cadence Design Systems     - Terry Jernberg*
Green Streak Programs      - Lynne Green
Intel                      - Michael Mirmak*
Mentor Graphics Corp.      - John Angulo*
Micron Technology          - Randy Wolff*
Sigrity                    - Sam Chitwood*
Teraspeed Consulting Group - Bob Ross*

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Michael noted that all available meeting minutes have been posted to 
the website.  Minutes for two meetings are missing, though these meetings
may have been cancelled.  Attendees are invited to review the text and
provide feedback.

No patents were declared.

The team reviewed proposed changes to the draft Touchstone 2.0 to 
address 2-port network ordering: N11, N12, N21, N22 vs. N11, N21, N12, N22.
The latter is the current Touchstone assumption, while the former is a
more natural ordering followed by 3-, 4-, etc. port network data within
Touchstone.  Bob created text, with comments from Radek, Patrick Zabinski
and others, to add a [Two-Port Order] keyword specifying which order is
used in any file.

Bob noted that no default assumption is used.  [Two-Port Order] is 
required if 2-port data is present in the file.  It only applies to
2-port network data.

Radek stated that a default might be possible, but that he has no objection
to the assumptions as-written.  In a separate e-mail message, he suggested
using [Two-Port Data Ordering] and 12_21 | 21_12 in place of the proposed
text.

Bob supports using 12_21 | 21_12 as more clean, while the team agreed to use
[Two-Port Data Order] as the final keyword text.  Bob and Radek suggested 
using N rather than X to represent abstract data pairs in the text.

Michael will complete these changes and send to IBIS Open Forum for continuing
review-and-comment period.  Bob requested a quick internal review for
typographical errors.

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Michael reviewed his proposed ICM-IBIS links.  The proposal makes few 
changes to the existing syntax of either IBIS or ICM, but does document
some required usage that would not be parsed by either the ICM or IBIS
parsers.  [Pin Mapping] and other existing keywords are supported as-is.

John Angulo expressed support but also regret that the connecting syntax
cannot be parsed.  Michael suggested an optional IBIS parser switch that might
activate the ICM parser and check for the correct connections between the two.

Bob expressed concern about dangling nodes with [External Circuit]. Outside
of ICM, the specification should not allow these.  Bob also noted that ideal 
buffer supplies for models in SPICE implementations may
get messed up when [Pin Mapping] is missing but ICM interconnect information 
is available.  

Sam added that there's no need to require [Pin Mapping] if ICM is used with 
[Model], [External Model], as some simulation applications don't use or 
aren't always interested in coupling.  Discussion ensued.

Michael agreed that certain cases that omit [Pin Mapping] and explicit
power or ground pins won't have defined connections for buffer supply rails.
ICM could then document redundant or confusing information.  He will send out
relevant examples.  He asked Bob to provide drawings or model cases where
on-die node references would be problematic.

Discussion will continue next time.

John Angulo suggested that use of [External Circuit] with [Model] would 
assist in making ICM connections work for stacked-die implementations.
He will sketch out the approach and a BIRD for this.

AR: Michael to complete Touchstone 2.0 revisions.
AR: Michael to send out pathological examples involving ICM-IBIS.
AR: Bob to send out example drawing for on-die connections of concern.

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Team Objectives:
1) complete ICM-IBIS linking BIRD and any associated changes to the 
   ICM specification
2) update the ICM specification, if needed, to clarify the mapping of 
   ICM nodes to S-parameter ports
3) complete a specification for "Touchstone Plus" or similar 
   industry-standard definition for Touchstone-like files, to include 
   complex impedance references, removal of limits on the maximum number
   of ports and per-port impedance references