Minutes from the 26 November ibis-atm meeting are attached.
IBIS Macromodel Task Group
Meeting date: 26 November 2019
Members (asterisk for those attending):
ANSYS: Dan Dvorscak
Curtis Clark
Cadence Design Systems: Ambrish Varma
Ken Willis
Kumar Keshavan
Intel: * Michael Mirmak
Keysight Technologies: Fangyi Rao
* Radek Biernacki
Ming Yan
Todd Bermensolo
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. Justin Butterfield took the minutes.
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Opens:
- Michael asked if there is a meeting schedule for the rest of the year. Arpad
plans to discuss the upcoming meetings next week.
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Review of ARs:
- Randy and Michael M. to invite DDR memory and controller vendors to comment
on new protocols.
- In progress.
- Bob to update BIRD197.6_draft_1 based on the discussion last week.
- Arpad reported this was done.
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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 November 19
meeting. Walter moved to approve the minutes. Bob seconded the motion.
There were no objections.
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New Discussion:
BIRD197.6_draft_2:
Bob shared BIRD197.6_draft_2, where he made some minor changes. He added
Michael's suggested sentences on page 2 in the rules section. He moved the
example to after the rules to directly relate to the Other Notes section. He
changed the wording from "between" to "range" since range includes the end
points. He changed the wording of the sentence to "The EDA tool may shift the
output waveform by the DC_Offset Value..." Randy asked if we should label the
values as volts. Bob agreed this would be good to add the units.
Arpad asked about the default of the parameter. Bob stated he had asked the
question over the email reflector. Randy commented only when you specify
DC_Offset you need to give it a value. Bob noted in the case of no DC_Offset
parameter there would be no shift. Randy stated we have this situation now,
where some tools shift the waveform and some do not. Walter stated the EDA
tool
knows what the offset is, but it is not an input to the model currently. But,
there is nothing preventing the EDA tool from calculating this and using it.
Arpad noted DC_Offset is a Usage In parameter. If the parameter does not
exist,
then the AMI model does not expect it. Thus, there is no need for a default.
Bob noted that only the EDA tool knows the DC value. Arpad commented the IBIS
specification is not intended to tell the EDA tool what to do; it only defines
how the EDA tool can get information from the model. Bob stated, if we don't
want to specify a default, that is fine.
Randy commented there are some EDA tools which provide the AMI_GetWave input
waveform data with the DC shift included. Michael agreed this is an issue, and
he noted the Rx needs to know if the DC information is in the impulse response.
Randy noted this affects how the model will sample the data. Walter stated the
waveform shifting and impulse response shifting are different issues. In the
impulse response, you could add a dirac delta function. Michael commented the
DC_Offset parameter should be sufficient. Walter noted the sentence: "This
shall include, but is not limited to, channel effects as well as the impact of
any equalization imposed by the transmitter." should be a discussion topic for
next time.
Arpad asked, for the Rx GetWave, if the waveform should include the DC shift
and
if this is defined in the specification. Walter stated this is defined in the
specification and it should not be added.
Arpad asked about the default issue. If there was a default value for the
DC_Offset, the model would not know what to do with it. Randy agreed there is
no need for a default. Bob agreed we do not need to add text about the default.
Bob noted he changed the sentence on page 2 to "centered at zero volts". Arpad
asked about the word "centered", and he suggested to be somewhat vague and not
go into details about the waveform. Bob responded there could be many types of
centering. Arpad stated, depending on the bit stream, the average may not be
in
the middle. Randy suggested to use the phrase "swings around zero volts".
Radek suggested to use "plus Vm" and "minus Vm". Mike suggested to remove the
word "centered". Walter noted the point is that this is a single-ended signal
where above zero volts is a '1' and below is a '0'. The goal is that the
threshold is 0V. Mike suggested the range of the signal should enclose zero
volts. Arpad agreed with the phrase "signal shall swing around zero volts".
Bob took an AR to send out the BIRD197.6 draft with the changes as noted.
Walter asked for Arpad and Radek to carefully consider the sentence added by
Michael. ("This shall include, but is not limited to, channel effects as well
as
the impact of any equalization imposed by the transmitter.")
Enabling Back Channel Interface in statistical mode:
Arpad noted he sent a list of options which included the proxy method, which
could be possible with a specification change. Walter commented the proxy
method would not require a BIRD. Arpad noted this would work if there were a
standard for the protocol in the specification. Walter noted this was not
Wei-hsing's approach, and if some vendors wanted to get together and define the
protocol, they could. Arpad will remove the proxy approach from the list of
possible approaches for consideration in the next meeting.
- Walter: Motion to adjourn.
- Randy: Second.
- Arpad: Thank you all for joining.
AR: Bob to send out BIRD197.6_draft3.
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Next meeting: 3 December 2019 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
