Minutes from the 31 Mar 2015 ibis-atm meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 31 March 2015
Members (asterisk for those attending):
Altera: David Banas
ANSYS: * Dan Dvorscak
* Curtis Clark
Avago (LSI) Xingdong Dai
Cadence Design Systems: Ambrish Varma
Brad Brim
Kumar Keshavan
Ken Willis
eASIC David Banas
Ericsson: Anders Ekholm
IBM Steve Parker
Intel: Michael Mirmak
Keysight Technologies: * Fangyi Rao
* Radek Biernacki
Nicholas Tzou
Maxim Integrated Products: Hassan Rafat
Mentor Graphics: * John Angulo
* Arpad Muranyi
Micron Technology: * Randy Wolff
Justin Butterfield
QLogic Corp. James Zhou
Andy Joy
eASIC Marc Kowalski
SiSoft: * Walter Katz
Todd Westerhoff
* Mike LaBonte
Synopsys Rita Horner
Teraspeed Consulting Group: Scott McMorrow
Teraspeed Labs: * Bob Ross
(Note: Agilent has changed to Keysight)
The meeting was led by Arpad Muranyi.
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Opens:
- Arpad: Would like to discuss a package modeling topic.
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Call for patent disclosure:
- None
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Review of ARs:
- Michael M update AMI Directionality BIRD
- no report.
- Arpad to review IBIS specification for min max issues.
- In progress.
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New Discussion:
PAM4 BIRD:
- Walter: We have an updated PAM4 BIRD to send out.
Package modeling:
- Arpad: We have new package formats but the legacy formats might still be used.
- Arpad showed a presentation.
- slide 1:
- Arpad: This is without [Pin Mapping].
- The inductors might not be present.
- In case 1 there might be [Package] or [Pin] RLC only.
- In case 2 there is a [Define Package Model]
- In case 3 the [Define Package Model] does not define some pins.
- In that case should the unmodeled pins use other mechanisms?
- Or should it be a short?
- There is no information on how power and ground pins are connected.
- Signal models should come form the package or pin.
- slide 2:
- Arpad: This shows [Pin Mapping] shorting pads together.
- Some inductors might get shunted together if the pins are also shorted
together.
- The question remains, how should unmodeled pins be handled?
- Merging parasitics into one pin might make sense.
- The specification does not say how to create this model.
- slide 3:
- Arpad: This shows power and ground pins not defined in [Define Package
Model]
- Maybe the [Pin] RLC or [Package]should be used.
- Using a short is a possibility.
- That would create some"packageless" pins.
- The pins could be shorted together.
- Without a combined model that will not work.
- slide 4:
- Arpad: Not all power and ground pads are shorted here.
- The spec doesn't tell us what to do.
- Those other pins can't be simulated anyway.
- slide 5:
- Arpad: This is from Randy's presentation.
- Randy: You may get ports lumped into a single capacitance.
- To make matrices the same size a lot of post-processing would be needed.
- That might be error prone.
- slide 6:
- Randy: Without [Define Package Model] there is a question how to split up
capacitance.
- With just [Package] it usually represents only signal pins.
- slide 7:
- Arpad: Only a complete [Define Package Model] is correct for PI.
- Merging parasitics would be desirable,but how will simulators deal with
it?
- This might be worthwhile because there probably will be more legacy
models.
- We would need to have this in the specification.
- Bob: It would have to be clear to users that only 1 power and 1 ground
would be used.
- Arpad: Agree, the BIRD hopefully captures that.
- Arpad showed a draft BIRD "Power Pin Package Modeling"
- Arpad: The analysis part is similar to the slides.
- No name yet for the new sub-parameter under [Pin Numbers].
- One paragraph becomes several paragraphs.
- The "as many names as" clause has been clarified.
- That needs to match the original intent of the spec.
- Mike: The order of hierarchy might be more explicit here.
- Arpad: For missing pins it states "may be merged", it's not required.
- Radek: It should be more precise than "may" or "should".
- Arpad: The sub-parameter tells the tool there is a merging pin.
- The sub-parameter is followed by a list of pin names.
- They have to be in [Pin] and have to be power or ground pins.
- Without [Pin Mapping] PI can not be analyzed.
- There are invalid combinations.
- With [Number of Sections] the new sub-parameter is not allowed.
- Randy said that is likely only with matrix formats.
- The other sub-parameters are allowed only when the new one is absent.
- There are other rules about names and buses.
- Pin names may span lines, but each line starts with the new sub-parameter.
- It may list only pin names not in [Pin Numbers].
- The EDA tool must short those pins to eliminate the possibility of
disconnected pins.
- Undefined pins must be disconnected.
- Radek: Does it have to be exhaustive or a subset of [Pin Mapping]?
- Arpad showed IBIS 6.0.
- Arpad: You still can have a mixed case.
- Bob: There is a question if we want that rule.
- Radek: We might have unusual groupings.
- What happens to pins not specified in [Pin Numbers]?
- Arpad: We could have a requirement for that.
- Randy: Agree, we could check for that.
- Bob: I would prefer a new keyword like [Merged Pin Numbers].
- Arpad: The merged pin would list the pins it merges.
- This compact.
- A new keyword might make it harder to see what is merged.
- Bob: It does not apply to the uncoupled case.
- Walter: Presumably Micron has models that tools don;t know how to handle.
- Randy: Yes.
- Walter: It would help to see the IBIS file as an example.
- Randy: OK.
- Walter: Will those models be converted to new formats?
- Randy: We have old models that will not change.
- Curtis: This BIRD defines a way to address the ambiguity, but there will
still be older models out there.
- Do we need to clarify how we expect things to be handled in these situations
with older models?
- Randy: We might look at going back and updating our older models.
- Walter: We introduce the BIRD, and for older models we assume user
documentation
or some other source explains what the model expects.
- Arpad: There is a question which version update this might go into.
- It could go to editorial to get it in sooner.
- Bob: I'm not sure the sub-parameter is needed.
- The buses might be merged by rules.
- Arpad: That may be true, I need to consider that.
AR: Randy provide example for new package BIRD draft.
AR: Arpad send draft package BIRD to Mike for posting.
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Next meeting: 07 Apr 2015 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
