Minutes from the September 12, 2017 IBIS ATM meeting are attached.
Randy
IBIS Macromodel Task Group
Meeting date: 12 September 2017
Members (asterisk for those attending):
ANSYS: * Dan Dvorscak
Curtis Clark
Broadcom (Avago): Xingdong Dai
Bob Miller
Cadence Design Systems: * Ambrish Varma
Brad Brim
Kumar Keshavan
Ken Willis
eASIC: David Banas
Marc Kowalski
Ericsson: Anders Ekholm
GlobalFoundries: Steve Parker
IBM Luis Armenta
Trevor Timpane
Intel: Michael Mirmak
Keysight Technologies: Fangyi Rao
* Radek Biernacki
Ming Yan
Maxim Integrated Products: Hassan Rafat
Mentor, A Siemens Business: John Angulo
* Arpad Muranyi
Micron Technology: * Randy Wolff
Justin Butterfield
SiSoft: * Walter Katz
Todd Westerhoff
Mike LaBonte
Synopsys: Rita Horner
Kevin Li
Teraspeed Consulting Group: Scott McMorrow
Teraspeed Labs: * Bob Ross
TI: Alfred Chong
The meeting was led by Arpad Muranyi. Randy Wolff took meeting minutes.
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Opens:
- None.
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Review of ARs:
- Radek write BIRD 158.6 draft 5 as discussed.
- It is not finished but BIRD is modified based on comments from 2 weeks ago.
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Call for patent disclosure:
- None.
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Review of Meeting Minutes:
Arpad stated there were minutes from two weeks ago by Mike to review. Dan
moved to approve. Walter seconded the motion. There were no objections.
Arpad stated there were minutes from last week's meeting distributed by Curtis
to review. Dan moved to approve. Walter seconded the motion. There were no
objections.
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New Discussion:
BIRD158.6:
Arpad noted we are mostly done with technical discussions. Radek was asked to
clean up some of the drawings in the BIRD.
Radek shared draft 5 of the BIRD, still a work in progress.
Radek accepted all the changes form Walter's version. The document now shows
only Radek's changes. The transmitter analog circuit drawing was updated
based on Bob Miller's comments. Arpad asked if the decision was to label
buffer or pad terminals. Radek noted we are differentiating between buffer
and pad terminals in the BIRD. Radek did not think a final decision was made
on naming the terminals.
Radek stated that another change is no numbering of the package subcircuit
terminals in the diagram on the top of page 7. A statement was added about
inclusion of on-die interconnect parasitics. The Ts4file_Boundary text was
removed following the removal of the keyword and associated keywords.
Guidelines for using different package models in the .ibs file were added,
including two options provided to the user. The last option mentions
[Interconnect Model Set Selector]. Bob commented that Radek was documenting
all combinations of package models existing in IBIS. Arpad noted that
[Interconnect Model Set Selector] will need to change due to the latest
discussions on BIRD189.
Arpad asked why all these package precedence rules were being discussed here
in this BIRD. This BIRD is somewhat unrelated to package models in IBIS.
There are other places where this hierarchy is described in the spec. Radek
responded that we are documenting how 4-port differential data must be
connected properly by the user. Consistency should be expected by the tools
when they use the package model from the .ibs file. He is not describing
precedence rules, he is describing what the model should look like.
Arpad asked for a high level overview of section (b). What is new in this
section that doesn't exist in the specification yet? Radek responded that
let's say you have a 50x50 matrix in the package model. The text says how you
should create the package model for two pins. No text was added yet for
handling the power supply pins that may be included in a new Interconnect
Model. Arpad asked again if any new information on package modeling in IBIS
was new. He did see some new text related to coupling in matrix models.
Bob stated that for multiple channels, the coupled matrix package model could
include all of the coupled channels, not just a single channel. Also, there
is language defining a reference. Bob wasn't sure what the triangle symbol
means in the Ts4file picture. A terminal on the buffer may not be the
reference. Arpad asked if the triangle was implying the Node 0 connection.
Walter said the ground symbol is the local reference point for the
measurement, which is the local reference point. It is not Node 0, it would
be pulldown_ref or gnd_clamp_ref for a buffer. Radek said that the "Ref" node
is all the same point, but not necessarily node 0.
Walter stated that if you are doing ground based simulation, then all the
points are node 0. If you are doing local grounds, then the ground symbol
represents local ground for those measurements. Arpad said that considering a
Touchstone file that represents a circuit trace, with a common reference for
all its ports, then Walter's statement can't be true because ports are many
inches apart and referencing at both ends can't be the same. Walter responded
that either you assume ground based simulations where they are all tied
together and Node 0, or you should wrap that S-parameter and use a local
reference port per port. The grounds on one side are not the same as the
grounds on another side. If you use the shortcut, then it doesn't matter.
Walter confirmed that there are three referencing options in IBIS-ISS. You
can have no reference terminal assuming Node 0 as the reference, an N+1
terminal that is the reference, or a local reference per port, for a total of
Nx2 terminals.
Radek noted that the "Ref" symbols in his diagram should be the same node.
Walter agreed with Arpad that the description of the package modeling options
did not need to be in the BIRD. The language does not exist for [External
Model], so it is not needed for this. This BIRD describes a shortcut similar
to [External Model]. Bob noted we don't support package models in [External
Model], but the EDA tool can bring in package information external to the
[External Model] any way it wants to. Arpad said that in terms of the BIRD,
this information should not be in this BIRD. If it needs to be in the
specification, then it should be a separate BIRD.
Bob noted in this BIRD there is the word package, and the package model is
restricted in the way it hooks to the Ts4file. He thinks you could use
standard language defining how to use IBIS package models.
Arpad stated that section (a) talks about how to zero out package data in the
IBIS file. He sees the EDA tools handling of the package model as outside
this BIRD. Radek noted the power supply pins are not talked about in this
BIRD. Bob noted that the package model is connected by pin numbers. Bob
thought EDA vendors already have solutions for package model inclusions with
IBIS-AMI. He doesn't know if this is a generic IBIS file or an outside
Touchstone file. Do we get into this now, since we don't have a specific
syntax for bringing in Touchstone files?
Arpad asked if the triangle in between the Vp and Vn voltage sources is Node
0. Radek noted that a differential port requires three terminals, and the
third node is typically Node 0. Bob concurred that this should be an ideal
Node 0 voltage connection. Arpad wanted to make sure it wasn't a noisy node.
Arpad noted that he thought the text on the package model options should not
be in the BIRD. Walter moved to remove the text related to the package model
options from the BIRD. Arpad noted the package text could be included in a
separate BIRD. Arpad seconded the motion.
The vote tally was:
ANSYS - abstain
Cadence - abstain
Keysight - no
Mentor - yes
Micron - yes
SiSoft - yes
Teraspeed Labs - yes
Arpad asked Radek to remove the text. Radek questioned which text should be
removed. Walter noted that he wanted all the text related to package models
removed. Walter asked Radek to send him the BIRD with the corrected pictures,
and he would finish the editing [AR].
AR: Walter to finish editing of BIRD158.6 Draft 5.
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Next meeting: 19 September 2017 12:00pm PT
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IBIS Interconnect SPICE Wish List:
1) Simulator directives
