Minutes from the 4 Jun 2019 IBIS ATM meeting are attached.
Mike
IBIS Macromodel Task Group
Meeting date: 4 June 2019
Members (asterisk for those attending):
ANSYS: Dan Dvorscak
Curtis Clark
Cadence Design Systems: * Ambrish Varma
Ken Willis
Intel: Michael Mirmak
Keysight Technologies: Fangyi Rao
Radek Biernacki
Ming Yan
Stephen Slater
Maziar Farahmand
Mentor, A Siemens Business: * Arpad Muranyi
Micron Technology: * Randy Wolff
* Justin Butterfield
SiSoft (Mathworks): * Walter Katz
* Mike LaBonte
SPISim: * Wei-hsing Huang
Teraspeed Labs: * Bob Ross
The meeting was led by Arpad Muranyi. Mike LaBonte took the minutes.
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Opens:
- Mike LaBonte offered to take minutes.
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Review of ARs:
- Randy to update the C Comp Model draft with today's discussed changes and
send it to ATM for review.
- Done. Mike LaBonte had posted not the May 21 version, but the May 30 version
with updates from the meeting. Bob Ross asked if that was the latest
version.
Mike said it was.
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Call for patent disclosure:
- None.
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Review of Meeting Minutes:
Arpad asked for any comments or corrections to the minutes of the May 28
meeting. Randy Wolff moved to approve the minutes. Walter Katz seconded the
motion.
There were no objections.
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New Discussion:
Complex C_comp modeling:
Randy Wolff said for a C_comp model the driving/non-driving mode must be set.
We need
to decide what should be done if there is no [C comp Model] defined for
non-driving mode.
Arpad proposed falling back to the original C_comp for non-driving mode. Randy
proposed
Bob said an I/O model could always use to full C_comp if non-driving mode is
not defined.
He asked how this would affect Submodel. Arpad said Submodel C_comp was not
used.
Bob said a Submodel for the driver or receiver might select a different
capacitance.
Walter said C_comp would be used for generating the k-t function, not a
subcircuit.
Therefore C_comp must be kept for driving mode. A receiving mode C_comp is
needed.
Arpad asked if this would be in addition to the main C_comp or a substitute.
Walter said it would be a substitute. Bob said the receive C_comp is the more
useful one, because important reflections come from there. Walter felt they
were
both important. Arpad asked if it would make sense to fall back to original
C_comp,
because it is required. Randy said [C Comp Corner] is required with [C Comp
Model].
We agreed to falling back to [C Comp Corner] values for missing non-driving
C_comp.
BIRD197.3_draft_4(DC_Offset):
Arpad Muranyi showed a DC_Offset presentation from Fangyi Rao. Arpad said
Fangyi was
unable to discuss it this week. Walter Katz said in approach 1 shown on slide
1,
the latch was essentially centered around 0V. In approach 2 the latch was at
some
non-zero voltage. The model would be informed which approach was used and what
the
offset should be in approach 1. Slide 2 showed an arrangement with a
comparator, with
the reference voltage provided. The VrefDQ would not be exact because of step
size,
and the model would not know if it was too high or too low relative to the
ideal offset.
This could be compensated in the model. Arpad said the presentation could be
sent
the email list.
Randy Wolff said comparing DDR5 waveforms with no DFE to IBIS-AMI output could
only be
done with level adjusted output. Arpad agreed that some work was needed to
overlay
waveforms. Walter felt tools should have no trouble implementing that. Ambrish
Varma asked if the voltage would be the same as with a non-AMI model. Walter
said
it would not. Ambrish said the tool would shift the voltage level back as
needed.
Walter agreed. Arpad noted that getting the right amount of shifting was
necessary.
Walter said the small 3 or 4 mV shift due to resolution would be handled.
Arpad noted
that the presentation was using 0.4V shift. Walter said controllers would
determine the
right voltage by sweeping up and down until it finds errors, finding some
mid-point.
The mapping of register values to voltage may be non-linear, and the DLL does
not
know about that. Arpad suggested models that report actual offset voltages
should be
supported. Walter said that could be done. The model could output the voltage
value
for the DQ register setting it was using, and the tool could use that as the
threshold.
Bob Ross asked if the this would involve rejecting the BIRD. Arpad noted we
only have
a BIRD draft for BIRD197.3. Walter said our choice would be only whether to
submit it.
Ambrish agreed.
Digital signatures:
Walter said some companies would prefer not not to accept unsigned DLLs. Mike
LaBonte
said signing should up to model makers, IBIS need not do anything. Walter
suggested we
could make a simple statement that DLLs could be signed. Arpad wondered if we
should
offer some kind of certification service. Walter suggested IBISCHK could
report simply
if a signature is found, no more. Arpad asked who does the signing. Could IBIS
do it?
Ambrish asked if documents were being signed for this. Mike said the digital
signatures
were embedded in executable file headers, and that the certificates could be
seen on
Windows by inspecting the Security properties of an executable or DLL. IBIS
would have
difficulty obtaining a certificate because we are not an incorporated entity.
Also the
models would be "from IBIS" in that case, not the vendor. Wei-hsing said it
would be
necessary to pay for certificates, since self-signed models would be rejected.
Yearly
renewal payments was required for certificates.
- Ambrish Varma: Motion to adjourn.
- Walter Katz.: Second.
- Arpad: Thank you all for joining.
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Next meeting: 11 June 2019 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
