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IBIS INTERCONNECT MODELING AD HOC TASK GROUP MEETING MINUTES
Meeting Date: January 10, 2007

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

Attendees:
----------
(* denotes present)
Agilent                    - Chaitali Biswas*, Sanjeev Gupta*, 
                               John Moore*, Tina Sun*
CST                        - Fabrizio Zanella*
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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Next Meeting:
Wednesday, January 24, 2007

               Telephone     Bridge   Passcode
              916-356-2663      5     310-8227

LiveMeeting Details: (TBD)

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Michael Mirmak summarized the objectives of the Ad Hoc Interconnect 
Working Group (see list below).  He then turned the meeting over to 
John Moore of Agilent, to present on Touchstone(R) referencing issues.

John showed that "ports" in Touchstone(R) include both measurement nodes
and their respective references.  As a result, a five-port (5x5 matrix
or s5p) Touchstone(R) S-parameter file may be generated from a 10 node
circuit, a six node circuit or a five node circuit, depending on whether
the circuit includes indepedent measured reference nodes for each node of
interest, one reference node for the other five nodes or even five nodes
measured with reference to a universal point not included in the circuit.

Sam Chitwood agreed, adding that S-parameters make use of a loop concept,
and that the specific details of the reference node are irrelevant so long
as the loop data is preserved and is self-consistent.  

Sam noted that the model author needs to ensure the linkages between
the Touchstone(R) data and the ICM ports are correct; tools would have no
means to verify or correct a problem with reference nodes.  Michael 
suggested that any current ICM models should be assumed to use a universal
reference "ground" node not part of the circuit.  Both Bob Ross and John
Angulo suggested that few ICM models exist that use S-parameters and that
any ambiguities in interpretation of today's ICM simply be accepted.

The rest of John's presentation addressed complex impedance references.
He explained that most simulators today use the Kurokawa convention with
real valued reference impedances to express power waves in terms of Z 
parameters.  The common simplifications of Kurokawa's definitions do not 
work for imaginary reference impedances.  To maintain consistency, an 
assumption of real values on the reference impedance can be assumed, 
unless a "common standard can be established in the circuit simulation 
community" for complex reference impedances.  He added a specific
set of proposal options to address this issue in Touchstone(R), noting
that Agilent was willing to allow standardization of an expanded
Touchstone(R) format.  

The next meeting will address John's proposed options regarding complex
reference impedance values in Touchstone(R).  Additionally, the team will
consider how to support clear ICM reference connections to Touchstone(R) 
ports.

ARs
-----

Sanjeev/Bob - provide separate simple diagrams to show how port 
              definitions actually work in Touchstone; comments on node
              mapping are welcome
              DONE
Michael     - resend proposed IIRD to add ICM S-parameter reference nodes


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