Minutes from the 2 February ibis-atm meeting are attached.
IBIS Macromodel Task Group
Meeting date: 2 February 2021
Members (asterisk for those attending):
Achronix Semiconductor: Hansel Dsilva
ANSYS: Curtis Clark
* Wei-hsing Huang
Cadence Design Systems: Ambrish Varma
Ken Willis
Jared James
Google: Zhiping Yang
Intel: Michael Mirmak
Kinger Cai
Alaeddin Aydiner
Keysight Technologies: * Fangyi Rao
* Radek Biernacki
Ming Yan
Todd Bermensolo
Rui Yang
Luminous Computing: David Banas
Marvell: Steve Parker
Mentor, A Siemens Business: * Arpad Muranyi
Micron Technology: * Randy Wolff
* Justin Butterfield
SAE ITC Jose Godoy
SiSoft (Mathworks): Walter Katz
Mike LaBonte
Teraspeed Labs: * Bob Ross
Zuken USA: * Lance Wang
The meeting was led by Arpad Muranyi. Justin Butterfield took the minutes.
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Opens:
- None.
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Review of ARs:
- Arpad to write a new BIRD to supersede BIRD204 with the proposed changes.
- Done.
- Fangyi to begin a Redriver Flow BIRD draft.
- Done.
- Fangyi to add additional variant and comments about which parameters are
new vs. existing to his slides.
- 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 January 26th
meeting. Randy moved to approve the minutes. Lance seconded the motion.
There were no objections.
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New Discussion:
Redriver Flow Issues:
Arpad asked if we can remove the sub-bullets on the agenda related to the
Redriver Flow BIRD proposals. The existing BIRDs will likely be overridden.
Bob suggested to table these items. When we are in a position to reject these
BIRDs, we can untable them. Bob moved to table agenda items 6a, 6b, 6c, 6d.
There were no objections.
Fangyi added two slides that discuss Variant 4 which is a simplified version
of Variant 3. In this proposal, the EDA tool always adds the upstream
cumulative impulse and the place holder in the impulse response matrix. He
added coloring to the slide to highlight what is new in the proposal.
Fangyi added a slide for notes on Variant 4. He suggested a Use_New_Flow
reserved parameter. He detailed the assumptions on the new flow, which
include that the models all must support the new flow and the models must be
Init only or dual models. Arpad suggested we need to spell out these rules
very precisely in the BIRD.
Bob asked, if you use the new flow, do you need the Init_Returns_Impulse
true. Fangyi replied, if the new parameter is true, then you need the
Init_Returns_Impulse true. If a model specifies this new parameter, then it
must return an impulse. Bob commented we need to think about the parser
checking these cases. Fangyi stated the parser can check this.
Arpad asked about the name of the Use_New_Flow reserved parameter. He was
concerned with using the word "new" in the parameter name. He suggested to
tie the name to IBIS 7.1. Fangyi replied we could called it
Use_Alternative_Flow. Bob agreed that "new" is relative. He was also
concerned with tying it to a version number. Arpad stated we can decide on
the name later. Fangyi agreed.
Fangyi shared the Redriver Flow BIRD draft, which is still a work in
progress. He listed Walter as a co-author. He detailed the three known
issues. The first issue is: the cumulative upstream impulse response of the
Redriver channel is not provided to the terminal Rx in Init. The second issue
is: the cumulative upstream impulse response of the Redriver channel is not
provided to either Tx or Rx in Init. The third issue is: the combination of
Tx GetWave model and Rx Init-only model leads to deconvolution in time-domain
analysis.
Fangyi noted we want to eliminate the need for deconvolution. The BIRD
introduces the additions to the impulse response matrix and the new
parameter. The alternative redriver simulation flow is introduced, and the
changes to the flow are detailed with text changes to Section 10.2.3.
Arpad asked whether it is required for the terminal Rx to have a GetWave
function if it has DFE for statistical simulations. Fangyi replied this is
not used in the statistical simulation. Arpad commented this is only true
for the terminal Rx in time-domain simulations, while the other Rx models
could be Init only models. Fangyi stated this is correct.
Bob asked about the Default for the new parameter which is listed as False.
He asked what happens if the parameter is missing. Radek stated, if the new
parameter is not present, the new flow does not apply. Arpad thought we have
a rule that Value and Default cannot coexist. He suggested we need to check
this. Default applies when there is a list, and the user does not select a
value. Bob commented, if Default is not given, it is the first value in the
list. The default could be noted in the text. Fangyi added text stating if
the new parameter does not exist it is assumed to be false.
Arpad asked about the AMI Parameter Rule #4, and how it applies in this. Bob
replied you can have a Default but no Value, or you can have a Value but no
Default. Arpad summarized, when the model maker writes the model, he can only
include one the other.
Fangyi asked what Default Illegal means. Bob replied this is for table
parameters. Randy suggested to add <Boolean_literal> as the default. Fangyi
made this change.
Fangyi noted the new parameter defines which flow will be used. We will need
to replace the words "new" and "old".
Fangyi stated the BIRD defines the enhancement of the new flow and proposed
additions to Section 10.8.1. He proposed to add these changes after the
existing time-domain flow. The new text discusses redrivers and retimers
separately. Fangyi also added new flow descriptions for statistical
considering both redrivers and retimers. Arpad stated we will need some time
to read this. Fangyi will send out the BIRD draft to the ATM reflector.
Bob stated this might be BIRD210. He asked if we are going to include this in
IBIS 7.1. Arpad stated it depends on how long the EMD proposal takes. Bob
commented from a parser standpoint this is a simple BIRD. Randy stated, if we
want to include this IBIS 7.1, he would like to have it introduced at the next
IBIS Open Forum meeting. Arpad commented we will need to set clear
expectations for the EDA tools with this BIRD.
- Randy: Motion to adjourn.
- Bob: Second.
- Arpad: Thank you all for joining.
AR: Fangyi to send out the Redriver BIRD draft and updated slides.
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Next meeting: 09 February 2021 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
