[ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

  • From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
  • To: <ibis-macro@xxxxxxxxxxxxx>
  • Date: Thu, 22 Apr 2010 16:22:01 -0700

Thank you Todd, Ambrish and Fangyi for the last few emails.
I finally realize that I completely misunderstood section
2.3 in the specification.  I was under the impression that
this section was a combined flow description that covered
both, statistical AND time domain simulations.
 
I was lead to this impression by the two preceding sections,
2.1 and 2.2 which seems to describe the statistical flow and
the TD flow.  (Is my understanding of that correct)?  I was
under the impression that section 2.3 was a glorified
combination of these two sections, explaining in great detail
how one or the other or both can be achieved using the various
Boolean switches available to us, in a step by step manner.
 
It seems that we should definitely edit section 2.3 to avoid
others to fall into the same misunderstanding, and/or add
a similar section to describe the statistical flow.
 
Let me think over this whole situation with this new understanding
and come back in a little while with some proposals on how we
could/should fix it.
 
Thanks,
 
Arpad
==================================================================


________________________________

From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Todd Westerhoff
Sent: Thursday, April 22, 2010 4:37 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference



Fangyi,

 

There's an important historical point worth mentioning here.

 

The flow described in section 2.3 of the current 5.0 spec is a
time-domain simulation flow.  If you look at the paragraph right under
the 2.3 heading, it says:

 

"The following steps are defined as the reference simulation flow.
Other methods of calling models and processing results may be employed,
but the final simulation waveforms are expected to match the waveforms
produced by the reference simulation flow."  "Waveforms" in this case
means the simulated response to actual stimulus patterns, not the
impulse / pulse response used by a Statistical simulation engine.  I'll
readily admit I'm splitting linguistic hairs, but that's the wave I've
always understood it. 

 

Section 2.3 was created in direct response to issues we had running
IBIS-AMI models in both the SiSoft and Cadence IBIS-AMI toolkits; issues
that resulted in the definition of the Use_Init_Output parameter.  Tests
with both toolkits in early 2008 showed that, in effect, SiSoft had
assumed Use_Init_Output would always be False, while Cadence had assumed
that Use_Init_Output would always be True.  Adding this Use_Init_Output
parameter to the spec allowed the model maker to declare (for models
that supported both Init and Getwave) whether the Init and Getwave calls
were to be considered independent (i.e. the model supported both
Statistical and Time-Domain simulation) or whether the calls needed to
be chained together (i.e. part of the model was in Init, part of the
model was in Getwave).  We saw merit in both methods of model
development, and allowed the model maker to declare which method they
had followed.

 

You are correct; the intent was that Use_Init_Output would have no
effect on a Statistical simulation, and would affect Time-Domain
simulation only.

 

The 5.0 spec doesn't explicitly define a Statistical simulation flow,
although it does establish all the model functions and controls needed
to enable it.  At present, there are both tools and models in the market
that comply with the 5.0 spec and support Statistical simulation.  That
being the case, it makes sense to clarify the specification and the
reference flow for both Statistical and Time-Domain simulation, which is
exactly what the flow discussions (and flow diagrams) were intended to
do. 

 

Hope that helps,

 

Todd.

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