[ibis-macro] Re: Analog BIRD comparison

  • From: Feras Al-Hawari <feras@xxxxxxxxxxx>
  • To: "Arpad_Muranyi@xxxxxxxxxx" <Arpad_Muranyi@xxxxxxxxxx>, IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
  • Date: Wed, 18 Jan 2012 09:27:44 -0800

Hello Arpad,

Yes, what you described below is right. 

Also, just to confirm that our message is clear:
- Bird 144 allows pointing to a Tstone file from the appropriate block (i.e., 
the External Model block, which is intended to encapsulate models that 
represent analog I/O buffers). 
- Hence, we are not limiting the usage of a Tstone model to the existence of an 
AMI section as proposed by Walter. However, based on our approach, the Tstone 
can be used to represent an analog I/O buffer with/without the AMI block.
- Also, our approach permits using a Tstone from an External Model in case we 
want to model RDL, ODT, or package.
- Yes Tstone models can be wrapped in an IBIS-ISS circuit, but since these 
models are very widespread we decided to propose an approach to enable the user 
to easily and directly use them in the appropriate IBIS blocks.
- Also, not to forget, based on our proposal we open the door to discuss the 
issue of supporting more than three corners.

Best regards,

Feras Al-Hawari
Cadence Design Systems


-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, January 17, 2012 10:01 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: Analog BIRD comparison

Ambrish,

To be precise, in Walter's "short hand" proposal discussed
today, it is the T-stone file name that is defined in the
.ami file.  But the entire "short hand" proposal works only
with AMI models, because all parameters, including the T-stone
file name come from the .ami file, and the .ami file can only
be found only if the [Algorithmic Model] keyword exists in a
[Model].

The S-parameter model instance in Walter's proposal is "defined"
in the specification, i.e. none of the IBIS related files have
a definition for it, the EDA tool just knows from the IBIS
specification what to do with the file name that comes from the
.ami parameter file.

So aside from the similarity of how the S-parameter instance is
connected in BIRD 144 and Walter's proposal, the major difference
is that BIRD 144 allows this to happen with legacy IBIS models
(and perhaps with AMI models also), while Walter's proposal allows
this to happen with AMI models only.

Another similarity is that both of these proposals are a subset
of the IBIS-ISS subcircuit general solution, which works for
both legacy and AMI modeling.

Thanks,

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


-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Ambrish Varma
Sent: Tuesday, January 17, 2012 8:11 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: Analog BIRD comparison

Arpad,
We are obviously fine with the S-Parameter part of Walter's proposal - just as 
long as it is wholly defined and contained in the IBIS file itself. If I am not 
wrong, and correct me if I am - Walter's proposals (both past and present) 
assume that the tstone files are declared in the AMI parameter file. 
We believe that there is a very clear distinction between the analog model and 
the AMI model and every attempt should be made to keep those two separate. 

Regards,
Ambrish. 
 
Ambrish Varma   |  Member of Consulting Staff
P: 978.262.6431   www.cadence.com
 
 
 
 
 

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, January 17, 2012 8:06 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: Analog BIRD comparison

Ambrish,

Thanks for your comments.  I think this might be
somewhat of a terminology issue.  I made that
comment based on the view that an S-parameter
block, if considered a circuit element, is connected
in a predetermined way, as described in BIRD 144, or
in Walter's proposal.  To me both of these are
predefined circuit topologies.

One might argue that the content of an S-parameter
can represent practically any circuit topology,
therefore BIRD 144 odes not describe a predefined
circuit topology, but that argument would also apply
to the S-parameter portion of Walter's proposal.

I am just trying to say that we should try to be
consistent.

We discussed two forms of Walter's "hard coded" circuits
in today's ATM meeting.  One that contains a predefined
RC circuit topology, and another that is replacing that 
with an S-parameter block.  Are you saying that the latter
is not predefined then, and consequently are you OK with
Walter's proposal as long as it makes use of S-parameters
only?

To me it seems that whether it is Walter's proposal or
BIRD 144, the direct connection of the S-parameter block
is pretty much the same in both proposals.  If we oppose
one, then we should also oppose the other.

Thanks,

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


-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Ambrish Varma
Sent: Tuesday, January 17, 2012 6:21 PM
To: IBIS-ATM
Subject: [ibis-macro] Analog BIRD comparison

Hi Arpad,
Thanks for putting these slides together. I would like to clarify something 
that you mentioned during the ATM call and also point out on slide 3 of the 
Analog BIRD comparison pdf. BIRD 144.1 does not describe a 'predefined circuit 
topology (that) eliminates the need for an IBIS-ISS subcircuit'. Only the 
latter part of the statement is accurate - it eliminates the need for an 
IBIS-ISS subcircuit when an external tstone file is being pointed to. It simply 
allows the model maker to directly refer the tstone file from the external 
model keyword. There is no attempt to pre-define a circuit or present a canned 
solution for any analog circuit. 

Another aspect of BIRD 144 is to allow user defined corners for analog models 
(described with a tstone file) for more than the allowed 3 corners *without* 
the need of an AMI parameter file. This functionality would keep the analog 
model entirely within the IBIS file and away from the AMI part of the 
specification. 

Thanks and Regards,
Ambrish. 

Ps: I changed the subject line to better reflect the topic of discussion.
 
Ambrish Varma   |  Member of Consulting Staff
P: 978.262.6431   www.cadence.com
 
 
 
 
 

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, January 17, 2012 2:23 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: IBIS-ATM teleconference - Agenda for 1/17/2011

I prepared a couple of slides to aid our
discussion today.

These slides are an attempt to summarize the
various arguments (pro/con) with the goal of
helping our decision process at the end.  I 
intend to keep adding more to these slides as
we go with our discussions.

Thanks,

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

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, January 17, 2012 10:58 AM
To: IBIS-ATM
Subject: [ibis-macro] IBIS-ATM teleconference - Agenda for 1/17/2011

Time:  January 17, 2012  Noon  US Pacific Time
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We need a volunteer to take minutes today.


Agenda
======

1) Opens
2) Call for any related patent disclosures
3) Review of ARs:


Walter:  Submit updated BIRD 123 to Open Forum
         - done (This is 123.2)

Arpad:   Submit Usage Out correction BIRD draft to Open Forum
         - done

Any other AR-s?


Old ARs:

Arpad:  Review the documentation (annotation) in the macro libraries.
        - deferred until a demand arises or we have nothing else to do


4)  Analog BIRDs discussion
    BIRD 122                                                 (Walter)
    - working documents: ISS_Buffer_BIRD.doc (May 17, 2011)
                         ISS_Package_BIRD_RevA.doc (May 27, 2011)

    BIRD 116, 117, 118, 129 for buffer modeling               (Arpad)
    BIRD 125  for package modeling                            (Arpad)

    BIRD 144, 145                                           (Cadence)


5)  BIRD 121.1, data management parameters (file support)    (Walter)
    - discussion, questions, comments?


6)  BIRD 124.1, dependency table                             (Walter)
    - questions, comments?


7)  Info, Out, InOut BIRD                                     (Arpad)
    - latest wording includes "in order to be compliant with this
      specification, Model_Specific parameters ... must not ...",
      and omits the word "simulation" so it's meaning doesn't have
      to be defined
    - any comments, questions on this draft?


8)  "Resolution"                                             (Walter)
    - do not include 5.0 rule descriptions in the 5.1 specification


Thanks,

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