[ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling

  • From: "Walter Katz" <wkatz@xxxxxxxxxx>
  • To: <kenw@xxxxxxxxxxx>, <Arpad_Muranyi@xxxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Mon, 20 Aug 2012 10:30:35 -0400 (EDT)

Ken,

 

I generally agree with your comments on how some very advanced users are
generating package and on-die models. The question is where to put the
"MCP". The IBIS approach, and the approach that supports most IBIS users
is to put the "MCP" inside of the IBIS file. For the advanced user who has
access to the package and die layout it is very convenient to put the
"MCP" inside the subckt that the package layout and IC layout tool
generates - as you do in your flows. 

 

It would be very convenient for your flows to have the x-y coordinate of
the package pins and die pads in the IBIS file. I would suggest for these
advanced applications to not complicate IBIS, but recommend that you add
an "MCP" section within IBIS using the same technique of adding "MCP"
records using the native IBIS comment character "|", similar to the way
you add "MCP" records to the SPICE subckts using the SPICE comment
character "*".

 

If you would prefer to add "MCP" data to the IBIS 6.0 specification, I
suggest you submit a BIRD to that affect.

 

Walter

 

From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Ken Willis
Sent: Monday, August 20, 2012 10:16 AM
To: Arpad_Muranyi@xxxxxxxxxx; IBIS-ATM
Subject: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling

 

Hi Arpad and Greg,

 

Good discussion on the package modeling. Just a quick look back on the
topic ... when the IBIS package modeling initially came out, there were a
lot of off-the-shelf packages and everybody was looking at basically
lumped per-pin parasitics. Putting together a syntax to cover that was
fairly straightforward.

 

It is a big contrast to what is going on now, with so many huge, custom,
flip chip packages. Multiple die, wirebond and flip-chip, interposers,
etc. The advanced packages are much more like mini-PCBs than the original
packages IBIS covered. There is all kinds of coupling to include, ex.
via-via, wirebond-trace, etc. And if you want to do power-aware
simulations, that means you have to include the package PDS, which adds
more elements and ports and complexity. And not only that, but you really
have to include the on-chips PDS then too, and be able to hook it up to
the package and IO drivers/receivers. That brings yet another level of
modeling to the picture.

 

Looking at these kinds of challenges, it appears unlikely to me that we
will be able to spec our way out of it with new syntax in EBD or other
approaches. All of these kinds of things are done today with Spice
subcircuits (including incorporation of sparams). So leveraging regular
Spice syntax (through ISS), and not inventing new syntax, makes sense to
me. I don't think any of that wheel needs re-inventing.

 

Once you have the subcircuits, the challenge then becomes hooking them up
properly in a full topology. We need some intelligence in the subcircuits
that helps users hook them up, and also enables automation to occur in EDA
tools. In the Sigrity flow, this was done by just putting a simple MCP
(Model Connection Protocol) header into the Spice subcircuits as comments.
MCP has been offered to the IBIS standard more than once, I think we
should consider it in these discussions. This kind of simple augmentation,
together with the well-defined Spice syntax that has worked for decades,
would be very powerful if standardized in IBIS.

 

thanks,

 

Ken Willis

Cadence Design Systems

980-245-7595

 

  _____  

From: ibis-macro-bounce@xxxxxxxxxxxxx [ibis-macro-bounce@xxxxxxxxxxxxx] On
Behalf Of Muranyi, Arpad [Arpad_Muranyi@xxxxxxxxxx]
Sent: Thursday, August 16, 2012 6:57 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling

Greg,

 

You raise pretty good questions.  Here is the way I see the

situation.

 

Yes, essentially the discussion revolves mostly around how

to write the new IBIS package modeling specification which 

basically consists of instantiating the IBIS-ISS subcircuits

and/or the Touchstone files and connecting these with the

terminals of the IBIS [Model]s, die pads, and device pins.

In short, instantiation and connection, i.e. netlisting.

 

The reason I am so vocal about developing a general purpose

syntax that covers all situations is to avoid:  "to take a lot

of effort and time to ferret out all the permutations and contingencies".
My

favorite example is SPICE, they didn't invent many different

syntaxes of instantiating resistors, inductors and capacitors

and all of their permutations, they just defined

 

ElementName  n+  n-  value

 

and it works miraculously for all of these elements in all

possible combinations.

 

Regarding whether it makes sense for us to spend the time to

develop a specification like that, I see it this way:

 

Given a specification, the model maker can write the models,

instantiate them and connect them, all in the .ibs and .pkg

files.  Do it once, and it works in all EDA tools, for all

users.  What you are suggesting is the opposite.  The model

maker just writes a model any whichever way they feel like it,

toss it over to the users, and every single user will have to

figure out how to instantiate and connect them.  Add to that

that not all users might have the expertise to do this, and

different EDA tools might need this done in different ways.

Now we multiplied the amount of work needed to be done by

the number of users and possible the number of EDA tools.

Even the model makers might have to put in more time to

help their less experienced customers, so they might end

up having to work on this together with (several of) their

customers.

 

So the model maker will do more customer support, and all the

customers will spend a lot of their time on fiddling with the

models to get them to run.  This is a very good way to make the

design time of every new product longer.  Also, this does not

go together very well with the last letter of the acronym "EDA".

 

Why shouldn't we apply a little factoring and let the model

maker do this once, and let the users plug and play with 

designing their products, instead of wrestling with the

models?

 

Like I said before, if I am completely off the wall, let me

know and I will shut up do something else...

 

Thanks,

 

Arpad

==============================================================

 

 

 

 

 

From: Gregory R Edlund [mailto:gedlund@xxxxxxxxxx] 
Sent: Thursday, August 16, 2012 12:59 PM
To: Muranyi, Arpad
Cc: IBIS-ATM; ibis-macro-bounce@xxxxxxxxxxxxx
Subject: Re: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling

 

Arpad,

If I understand the proposals on the table, the main thing we're trying to
accomplish with the new package syntax is instructing the EDA tool in how
to connect the ISS or Touchstone package model.  Correct me if I
misunderstand.  It's going to take a lot of effort and time to ferret out
all the permutations and contingencies.  I'm questioning which option is
more painful:  spending the effort and time or connecting the package
model manually.

We will always get a wide variety of package models that depend on
personal preferences, what they're trying to model, etc.  If people stay
within the ISS and Touchstone specs and document what they've done, we
should be OK.  I want to stress the word document.  As a model user, I
will always want to know about the internal structure of the model, what
tools were used to generate it, under what conditions it is valid, etc.
That means I will always need a PDF file to accompany the model.  May as
well tell me how to hook it up at the same time.  As I see it, this is
really a model quality issue.

Greg Edlund
Senior Engineer
Signal Integrity and System Timing
IBM Systems & Technology Group
3605 Hwy. 52 N  Bldg 050-3
Rochester, MN 55901



Inactive hide details for "Muranyi, Arpad" ---08/16/2012 09:17:19
AM---Greg, Thanks for your comments again. Certainly, we cou"Muranyi,
Arpad" ---08/16/2012 09:17:19 AM---Greg, Thanks for your comments again.
Certainly, we could do

From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
Date: 08/16/2012 09:17 AM
Subject: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling
Sent by: ibis-macro-bounce@xxxxxxxxxxxxx

  _____  




Greg,
 
Thanks for your comments again.  Certainly, we could do 
a survey on what people think we should spend our time
on.  But we need to make a good list then that people
could prioritize with numbers.  Some of that list could
come from the agenda I send out every week for the ATM
meetings, because I have a few topics listed there which
are ahead of us, but we don't get to discuss in the meetings
because we take the ones which are on the top of the list.
 
But regarding the package improvements question, at its
current state, the package modeling in the IBIS specification
is pretty much useless.  If we don't do anything about it, we
can pretty much say goodbye to anyone using it for anything
useful.  That means that you will get package models in all
kinds of different shapes and form, and you will constantly
have to tailor them to the tool you happen to be using for
any given project.
 
If you looked at the BIRDs list on the IBIS website:
 <http://www.eda.org/pub/ibis/birds/> http://www.eda.org/pub/ibis/birds/
and searched for "package",
you will see that the last BIRD was 64.4 in year 2000 adding
the [Alternate Package Model] keyword to the spec, and before
that we had BIRD 54 in 1998 with some corrections, and before
that we had BIRD 37.3 and 28.3 with some enhancements in years
1996 and 1996.  This means that the last time we enhanced the
package modeling syntax in IBIS was over 16 years ago!  To me
this alone is an indication that we should put a high priority
on upgrading the package modeling capabilities in IBIS, but 
this is with the assumption that we want to have a standard
for it.  If people don't want to have a modeling standard for
package modeling, we might as well drop the discussions today
and spend our time on other topics.
 
Thanks,
 
Arpad
=================================================================
 
 
 
From: Gregory R Edlund [mailto:gedlund@xxxxxxxxxx] 
Sent: Thursday, August 16, 2012 8:46 AM
To: Muranyi, Arpad
Cc: IBIS-ATM; ibis-macro-bounce@xxxxxxxxxxxxx
Subject: Re: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling
  

Arpad,

In addition to the actual model, I expect to get a document from the
supplier explaining how to use the model.  The automation is not a high
priority for me because it's not labor-intensive.  Getting the model to
run at all is definitely a high priority, and my EDA suppliers are saying
they have very little diagnostic information when a model crashes.  If the
model developer didn't use the same tool I'm using, that means I'm pretty
much stuck in the middle.  Neither the EDA supplier nor the model supplier
can help me debug the problem.

Since we all have limited resources, I would like to see us prioritize our
work items.  The package extension has the potential to generate a lot of
traffic and consume many weekly calls.  Is it the thing that will best
help advance the state of IBIS AMI in 2012?  Is there some way we can
survey the users to find out what their highest priorities are?

Greg Edlund
Senior Engineer
Signal Integrity and System Timing
IBM Systems & Technology Group
3605 Hwy. 52 N  Bldg 050-3
Rochester, MN 55901



Inactive hide details for "Muranyi, Arpad" ---08/15/2012 10:47:46
AM---Greg, Thanks for your comments. Like you, I would like "Muranyi,
Arpad" ---08/15/2012 10:47:46 AM---Greg, Thanks for your comments.  Like
you, I would like to see

From: "Muranyi, Arpad" < <mailto:Arpad_Muranyi@xxxxxxxxxx>
Arpad_Muranyi@xxxxxxxxxx>
To: IBIS-ATM < <mailto:ibis-macro@xxxxxxxxxxxxx> ibis-macro@xxxxxxxxxxxxx>
Date: 08/15/2012 10:47 AM
Subject: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling
Sent by:  <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
ibis-macro-bounce@xxxxxxxxxxxxx

  _____  





Greg,

Thanks for your comments.  Like you, I would like to see
more comments from other users too.

But to answer your question, "along with a document saying "use this model
for these pins""
is what we would like to make the .ibs and/or .pkg file
to do for you (based on a standardized specification),
so that you won't have to do it by hand.  Does that make
sense?

As an illustration I would say that we want to make a
specification which allows model vendors to send you a
machine readable netlist instead of a Word document
that describes what the circuit looks like.

Thanks,

Arpad
==========================================================

From:  <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
ibis-macro-bounce@xxxxxxxxxxxxx [ <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Gregory R Edlund
Sent: Wednesday, August 15, 2012 10:29 AM
To:  <mailto:wkatz@xxxxxxxxxx> wkatz@xxxxxxxxxx; IBIS-ATM;
<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> ibis-macro-bounce@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Straw Poll vote on IBIS-ISS Package Modeling
  

Here's one user's perspective:

I'm happy getting .s4p files from my chip suppliers along with a document
saying "use this model for these pins" (among other things).  And if
coupling is worth simulating, then I'm happy with an .s12p file.  I can
get along without a CAD file to tell me how to hook up the s-parameters in
the EDA tool.  Or is there something else going on that I'm not seeing?

To me, it seems like there are bigger fish to fry, e.g. getting IBIS 5.1
out the door, jitter modeling, error reporting when a DLL crashes, etc.

Any other users care to weigh in?

Greg Edlund
Senior Engineer
Signal Integrity and System Timing
IBM Systems & Technology Group
3605 Hwy. 52 N  Bldg 050-3
Rochester, MN 55901



Inactive hide details for "Walter Katz" ---08/14/2012 04:24:02
PM---[attachment "IBIS_ISS_Package_Modeling_120807.pdf" deleted "Walter
Katz" ---08/14/2012 04:24:02 PM---[attachment
"IBIS_ISS_Package_Modeling_120807.pdf" deleted by Gregory R
Edlund/Rochester/IBM]  [atta

From: "Walter Katz" < <mailto:wkatz@xxxxxxxxxx> wkatz@xxxxxxxxxx>
To: "IBIS-ATM" < <mailto:ibis-macro@xxxxxxxxxxxxx>
ibis-macro@xxxxxxxxxxxxx>
Date: 08/14/2012 04:24 PM
Subject: [ibis-macro] Straw Poll vote on IBIS-ISS Package Modeling
Sent by:  <mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
ibis-macro-bounce@xxxxxxxxxxxxx

  _____  





[attachment "IBIS_ISS_Package_Modeling_120807.pdf" deleted by Gregory R
Edlund/Rochester/IBM] 
[attachment "IBIS_ISS_Package_Modeling_Discussion_1_120814.pdf" deleted by
Gregory R Edlund/Rochester/IBM] 
[attachment "PackageFunctionalityStrawPoll.xlsx" deleted by Gregory R
Edlund/Rochester/IBM] 

All,

I have put 28 questions in a spreadsheet. I think it will take too much
time to do the voting in the meeting, so I request that you put entries
1:4 in column 1 of each question. The meanings of 1:4 are.
  


4

Advocate   I need this!


3

Support      I support this


2

Abstain       I have no opinion


1

Object         I object to this functionality


Return them to me or all IBIS-ATM and I will collate the results and
publish them by Tuesday AM. I am including the .xlsx file in case you have
difficulty editing the spreadsheet in the body of this e-mail. Also
including this and last weeks presentation.

Walter
  


4

Advocate   I need this!


3

Support      I support this


2

Abstain       I have no opinion


1

Object         I object to this functionality


 

 


 

Should we add keywords Pullup_Signal_name, Pulldown_Signal_name,
Power_clamp_Signal_name, and Ground_clamp_Signal_name to the [Model]
section?


 

Should we add a section to the .ibs file to define the voltage values of
supply signal names?


 

Should we add a list of supply die pad names?


 

Should we add an x-y coordinate for each pin and die pad?


 

 


 

Should we support two signal pins connected to the same die pad (Forked
Signal)?


 

Should we be able to associate a package model with a [Model]?


 

Should we be able to associate a package model with a Pin_name?


 

Should we be able to associate a coupled package model with a [Model]?


 

Should we be able to associate a coupled package model with a list of
Pin_names?


 

Should we support package models with coupling between signals and power?


 

Should we support a coupled package model that hooks up to two or more
[Model] names?


 

Should we support package models with more than 3 corners?


 

Should we support package Touchstone files directly?


 

Should we support sparse usage of large package Touchstone files?


 

Should we support package "Quadrants" (e.g. Banks, Interfaces)?


 

Should we support full package models?


 

 


 

Should we support on-die models?


 

Should we be able to associate an on-die model with a [Model]?


 

Should we be able to associate an on-die model with a Pin_name?


 

Should we be able to associate a coupled on-die model with a [Model]?


 

Should we be able to associate a coupled on-die model with a list of
Pin_names?


 

Should we support on-die models with coupling between signals and power?


 

Should we support a coupled on-die model that hooks up to two or more
[Model] names?


 

Should we support on-die models with more than 3 corners?


 

Should we support on-die Touchstone files directly?


 

Should we support sparse usage of large on-die Touchstone files?


 

Should we support on-die "Quadrants" (e.g. Banks, Interfaces)?


 

Should we support full on-die models?



Walter Katz
wkatz@xxxxxxxxxx
Phone 303.449-2308
Mobile 303.335-6156

GIF image

Other related posts:

  1. Home
  2. ibis-macro
  3. Archive
  4. 08-2012