Minutes, IBIS Quality Committee

05 April 2011

11:00-12:00 EST (08:00-09:00 PST)

ROLL CALL

Cisco Systems:                * Mike LaBonte
Ericsson:                     * Anders Ekholm
Green Streak Programs:          Lynne Green
Huawei Technologies:            Guan Tao
IBM:                            Bruce Archambeault
IOMethodology:                  Lance Wang
Mentor Graphics:                John Angulo
Micron Technology:              Moshiul Haque,
                                Randy Wolff
Nokia Siemens Networks:         Eckhard Lenski
Signal Consulting Group:        Tim Coyle
Teraspeed Consulting Group:   * Bob Ross
Texas Instruments:              Pavani Jella

Everyone in attendance marked by *

NOTE: "AR" = Action Required.

-----------------------MINUTES ---------------------------
Mike LaBonte conducted the meeting.

Call for opens and IBIS related patent disclosures:

- No one declared a patent.

- Mike: There was a quorum failure for the March 15 meeting
  - Time zone changes caused Eckhard and Anders to miss
  - Only Mike and Bob were present
  - Our last official meeting was Feb 22

- Bob: Will Anders report at the European summit?
- Anders: Maybe if the same presentation as last time can be used
  - Travel arrangements are not complete yet

AR Review:

- None

New items:

Discussion of External Test spec:
- Bob: Do we need a diagram to define "Who controls what"
  - There may be 10 different tests with different items
  - It has to be clear what files and objects are needed for each test
  - Then the testpoints have to be compared against waveforms
  - Should this be some general language?
- Mike: We should just present data, not a language
  - Terminology may be important to keep it clear
- Bob: We should keep it very general
- Anders: But if it's too limited no one will use it
- Mike: Should we start with file examples or with the hierarchy?
- Bob: It's easier to start bottom up
  - How we handle corners is important
- Mike: The example I created is inconsistent about corners
  - It uses columns in one place and typ/min/max keywords in another
- Bob: We would want to specify corner supply voltages, for example
  - The V elements would be in the test circuit
- Mike: That raises the question of which B element terminals to support
  - We were not going to supply stimulus voltage, for example
- Anders: For input buffers we need an analog source
  - Also we will want other probe points
- Mike: There are three categories of B element terminals:
  - The pad, which is absolutely required
  - Supplies, which are needed mostly for power system analysis
  - Die side controls, which are not necessarily analog controls
- Anders: We only need to specify probe points in the load connected to the pad
  - There may be VTT needed in the load circuit
- Mike: Do we force vendors to use the IBIS min/max voltages for their tests?
- Bob: SPICE can handle any voltage so that should be allowed
  - The termination voltage may be different from the driver
- Mike: IBIS models with wide voltage spreads are a problem
  - We might force model makers to use those voltages for testing
  - This might influence the choice of voltages
- Anders: They use one model for voltage tolerant buffers where they should
  have multiple
- Bob: Some buffers have fixed voltages regardless of supply
- Mike: That would be in the IBIS data
  - Should the driver supply voltages be supplied to the load circuit?
- Anders: No
- Mike: Agree, if anything there should be only a typ/min/max mode string
- Bob: A parameter could be used with one circuit
  - The circuit itself might define values
- Mike: It can have only one value in SPICE, not typ/min/max
- Bob: There is the "parhier" control that selectively overrides
- Mike: That was rejected by the ATM group
  - Such voltages should only be passed from the [External Test] keyword
- Bob: The example can either use separate subckts or parameters with one
  subckt
- Mike: We probably need to develop:
  - Examples (what we have here)
  - A call hierarchy, which probably should be a block diagram
  - The specification text
- Bob: We are trying to develop a general test definition language
  - The centerpiece is the test data
  - We are documenting how to get the test data
  - The test descriptions should be top level
  - Multiple corners should be part of each test
  - We need a probe point methodology too
- Anders: We just need to know the names of the probe nodes

Mike: Should I send out my example?
- Bob: Only once it is more developed
- Anders: I may miss the next meeting, and will certainly miss the one after

Next meetings:
- Next meetings Apr 12 and Apr 19

Apr 12 agenda:
- Review external test BIRD draft

Meeting ended at 12:17 Eastern Time.