Minutes from the 17 Apr 2018 ibis-atm meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 17 April 2018
Members (asterisk for those attending):
ANSYS: Dan Dvorscak
Curtis Clark
Cadence Design Systems: Ambrish Varma
Brad Brim
Kumar Keshavan
Ken Willis
eASIC: David Banas
GlobalFoundries: Steve Parker
IBM Luis Armenta
Trevor Timpane
Intel: * Michael Mirmak
Keysight Technologies: Fangyi Rao
* Radek Biernacki
Ming Yan
Mentor, A Siemens Business: John Angulo
* Arpad Muranyi
Micron Technology: * Randy Wolff
* Justin Butterfield
SiSoft: * Walter Katz
Todd Westerhoff
* Mike LaBonte
SPISim: Wei-hsing Huang
Synopsys: Rita Horner
Kevin Li
Teraspeed Consulting Group: Scott McMorrow
Teraspeed Labs: * Bob Ross
The meeting was led by Arpad Muranyi. Mike LaBonte took the minutes.
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Opens:
- None.
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Review of ARs:
- Arpad to contact Fangyi about whether he wants to be listed as an author on
the new BIRD to supersede BIRD158.7.
- Done. No reply yet. Fangyi may be away.
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Call for patent disclosure:
- None.
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Review of Meeting Minutes:
- Arpad: Does anyone have any comments or corrections? [none]
- Mike L.: Motion to approve the minutes.
- Radek: Second.
- Arpad: Anyone opposed? [none]
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New Discussion:
BIRD189 and BIRD158 related issues:
- Arpad showed a warning paragraph emailed by Radek.
- Radek: It combines and rephrases the two "Important" paragraphs.
- Arpad showed the two paragraphs.
- Bob: We have not discussed the third "important" message yet.
- Arpad: We did, at least a week ago. We were done with that.
- Walter: The last line should have "be" between "may" and "less".
- Radek: It should not have "less".
- Arpad changed that to "may be inaccurate".
- Bob: The results could be inaccurate regardless of the subcircuit content.
- Arpad: This paragraph says what the simulator should do.
- Radek: It has Michael's language about node 0 being treated as an additional
terminal.
- Michael: I came up with something different.
- Arpad showed Radek's original text.
- Arpad: We should say we highly discourage model makers from using node 0
because it may affect accuracy.
- Walter: The reason is that not all currents might go to reference nodes.
- Radek: This is the return path problem.
- The "shall be treated" phrase can be replaced.
- It is the same if A_gnd is used.
- Arpad: A_gnd is given in the [Interconnect Model]. Node 0 is hidden.
- Walter: Brad says they don't support node 0 in subcircuits. Not sure how they
do that.
- Radek: Node 0 and A_gnd give the same functionality.
- Michael M: A_gnd is not in IBIS-ISS. Do we need to mention A_gnd as existing
inside the subcircuit.
- Radek: We allow A_gnd for instantiation.
- Arpad: A_gnd is different from having it inside the subcircuit. You have more
control with A_gnd.
- Walter: We have to assume the person wrapping the models also creates them.
- Radek: Bring those nodes out can be tedious and error prone.
- Bob: ISS supports node 0 as global. It is not declared as a terminal.
- The user doesn't know if it's used, but an EDA tool could find out.
- Radek: We are trying to write a warning here.
- The EDA tool will know if node 0 is used.
- Arpad: Who are we writing the warning for? The maker, tool, or user?
- Michael M: All three. Model makers should be reminded to watch out.
- Sometimes users have to fix the models themselves.
- Bob: What should the checker say?
- Walter: This will be in IBIS, not checked.
- Bob: Someone should write a node 0 detection script.
- Michael M: It could be a differentiator for an EDA tool.
- Arpad: If all three should be warned, this needs to be worded differently.
- Walter cited his suggested wording.
- Walter: We are talking about uV to mV of effects.
- Radek: We should not try to quantify the problem.
- Michael M: We could keep the current sentence and add Walter's message.
- Walter: We should not "highly discourage". We should say what it will do.
- Arpad showed text from Walter.
- Walter described current loop issues.
- Bob: What's wrong with doing this in ISS?
- Walter: Nothing. People do it today, even in power aware simulations.
- Most of the voltage drop comes from the buffer itself.
- Arpad showed a modified warning message.
- Arpad: Is this acceptable.
- Michael M: That looks good.
- Radek: It does not mention A_gnd.
- Arpad added an A_gnd clause.
- Radek: It should not have "ground".
- Walter: That was because ground pins are used as references for measurements.
- Arpad: We could say it does not account for all current going through the
component's pins.
- Walter: IBIS is a databook component spec. Some of those pins are ground.
- I had a sentence about the historical use of "ground".
- Arpad: If done right, all current goes through the pins.
- This is an additional path.
- We should say that some current would not go to the pins.
- Walter: We should define what ground is.
- Bob: We do not agree on that. It would not support ECL/PECL.
- Michael M: It can mention pins, but it does not have to be exhaustive.
- Radek: What we have here is sufficient.
- Bob: In simulation node 0 is universal as a ground.
- Radek:
- Michael M: If we expect all current to go through the pins, the math will
not come out correctly.
- Arpad removed "ground" and the "power aware" clause.
- We agreed on the language.
- Arpad: Should this be "warning" or "important"?
- We agreed to make it a note.
AR: Arpad to send edited node 0 note text to list.
- Michael M: If we still agree on this we can resolve the remaining BIRD 189
issue comments in the next meeting.
- Michael M.: Motion to adjourn.
- Mike L.: Second.
- Arpad: Thank you all for joining.
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Next meeting: 24 April 2018 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
