IBIS FUTURES COMMITTEE MULTILINGUAL MODEL: Circuit Call REFERENCES

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IBIS FUTURES COMMITTEEMULTILINGUAL
MODELCircuit Call REFERENCES

• John Angulo
• 8th April 2004

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BIRD 75.8 Assumptions

• External Circuit
• Other than D_drive/D_enable/D_receive, ports have
  no predefined meaning or connection
• Circuit Call instantiates and connects them
• External Model
• All ports have predefined meanings and
  connections per IBIS version 4.0
• Pin keyword instantiates and connects them
• Assumptions
• External Circuit will model any buffer
  technology old IBIS cant handle
• Old IBIS structure is inflexible, so limit
  External Model to an upgrade path

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BIRD 75.8 Limitations

• External Circuit cant quite model a buffer
• No timing test load no flight time compensation
• No measurement thresholds no flight time,
  overshoot, hysteresis measurements
• External Circuit cant talk to a buffer model
• We can only connect an External Circuit to
  other External Circuits
• Use External Circuit for the interconnect
  cant use Model or External Model for the
  buffer
• Multilingual approach is limited in practice to
  package/interconnect or the buffer, not both
• External Circuit behavioral parameters for
  buffer modeling are still pending

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Practical Solution

• Let Circuit Call reference Model
• No syntax changes necessary
• Available ports are already enumerated in BIRD
  75.8
• Could use advanced package or die interconnect
  model together with multilingual buffer model, or
  old IBIS model
• No conflicts between old IBIS and nodal
  connections
• We already handle incomplete port mappings by
  defaulting to internal values, as seen in HSPICE
• We already let the user choose between internal
  values and external port mappings, as in HSPICE
  poweronoff

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