It has been pointed out to me that the minutes from the 24 Mar 2015
ibis-atm meeting have not yet been sent. They were ready to go last
week, so here I am taking that final step of actually sending them ;-)
Mike
IBIS Macromodel Task Group
Meeting date: 24 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: I have a spec clarification issue.
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Call for patent disclosure:
- None
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Review of ARs:
- Michael M update AMI Directionality BIRD
- Arpad: He reported this is in progress.
- Walter and Randy produce C_comp BIRD.
- Randy: Some progress, but we need to resolve issues about parameters.
- Arpad to review IBIS specification for min max issues.
- In progress.
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New Discussion:
PAM4 BIRD:
- Walter: Thanks to all who submitted comments.
- A list will be allowed to select NRZ or PAM4.
- There will be upper and lower timing offsets.
- The tool returns an impulse or waveforms, not an eye.
- Duobinary is a question.
- The keywords are named to not conflict later.
- Arpad: Should we number the thresholds?
- Walter: We called them PAM4_Upper, PAM4_Lower, PAM4_Center.
- Each scheme could have its own names.
- Mike: If NRZ and PAM4 are selectable, numbered thresholds might conflict.
- Walter: We should not have Duobinary until it is in use.
- Fangyi: Agree with Walter.
- An IC vendor suggested we use Rx_Clock_Recovery_Mean for the middle eye.
- Walter: In GetWave we get center eye clock_ticks.
- Offset would be better for that.
- For statistical would be offset from the mean.
- Fangyi: In TD offset is from the mean.
- Walter: SO we have upper and lower eye mean?
- Fangyi: In statistical it would be offset from the recovered clock.
- Walter: If the mean is 10ps from center, by default I use
- Normally there is only one clock for all 3 latches.
- There is no offset in time domain, you use clock ticks.
- A PAM4 has only one clock recovery.
- Upper and lower may have different phases.
- One offset for each segment should apply to TD and stat.
- Fangyi: So the offsets are added to the center mean?
- Walter: Yes.
- Fangyi: So clock_times is for the center eye.
- A numbered scheme would complicate that.
- Todd: I like the idea of numbering the eyes.
- Arpad: We could have zero, positive, and negative numbers.
- Todd: We have to know which eye the clock_times pertain to.
- Walter: A lot of places use upper and lower.
- If PAM5, PAM6, PAM7 were coming things would change.
- Mike:New modulations will have their own prefixes.
- Fangyi: We need to correct "bit time"
- Walter: Agree, it should be "symbol time".
- Fangyi: ?? should be an integer.
- Walter: Agree.
Co-optimization:
- Walter: No update for today.
- We should avoid dynamic modulation switching.
- We simulate at PHY level, not MAC.
C_comp:
- Randy: Curtis Clark sent comments.
- I added nodes for a differential receiver.
- Curtis had questions about how different simulators would handle it.
- Curtis: Walter said these models complicate extracting K(t).
- Bob's presentation shows how to move the measurement point.
- Maybe the K(t) should be in the IBIS file.
- Walter: The format would be simple.
- There would be four curves.
- Simulation would be easy.
- This may be harder for model makers.
- Arpad: Without V-T tables verifying would be harder.
- With the V-T load you should get the same waveform.
- You could have both.
- Radek: They might not agree.
- Arpad: Tools derive K(t) already , why have model makers do it?
- Walter: C_comp makes it hard to get it right.
- Curtis: Bob created a complicate system to get K(t).
- Walter: Tools reinvent K(t) every time they simulate.
- Mike: Wouldn't K(t) tables eliminate current differences among tools?
- Walter: Yes.
- Arpad: We should finalize the C_comp proposal before this.
- Arpad showed [Package] in the IBIS spec.
- Arpad: We have a series of overrides.
- In [Define Package Model] [Pin Numbers] it does not say they all have to be
in [Pin Names].
- The [Package] might be a partial model.
- The remaining pins might use defaults.
- For example Power and GND pins could be omitted from [Pin Numbers].
- The spec doesn't say what to do with them.
- Tools handle this differently.
- Some create a short, some leave it open.
- Mike: Can [Define Package Model] have both [Pin Numbers] and matrix formats?
- Bob: No they are mutually exclusive.
- A missing [Define Package Model] pin would fall back to [Pin] RLC, then to
[Package].
- Arpad: If no [Pin Mapping] there would be straightforward pin to pad paths.
- Why describe 10 power pads when I can describe one and leave the rest
disconnected.
- That would rely on [Pin Mapping] to connect them.
- It assumes shorts would not be created.
- Some tools will create shorts though, eliminating the model.
- Bob: A rail might be shorted to nine other rails through buffers.
- Randy: I get this with my models.
- With a power plane 10 balls are connected to the package.
- We shorted the powers together, same for grounds.
- In [Pin Mapping] all 10 pins are there but the package model has only one.
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Next meeting: 24 Mar 2015 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
