Hi,
Arpad;
Can
you clarify that whether both LTI_algorithms and
non-LTI_aglroithms are called in time domain simulation sequentially,
or one is
called in statistical simulation to provide modified impulses and the
other is
call in time domain?
Thanks,
Fangyi
Oh
well... I will throw in my $ 0.02 worth on this topic.
I
think we are mixing two things here, and our terminology
doesn't
help either. One is that we have this notion of
"Init",
meaning initializing the computer memory, etc... in
a
computer science sense, and the other is the two types of
flows,
LTI and non-LTI. To be honest, I never liked the idea
of
calling the "Init" function "Init", when its purpose was
to
execute the LTI algorithms.
If
this flow topic is now becoming such a big deal regarding
Init
and GetWave, why don't we give things a little more
descriptive
names? Let's have an Init (if necessary) to
really
do nothing but initializing memory, etc... and then
have
another function, say "LTI_algorithms" to do the LTI
signal
processing, and a third function that will do the
non-LTI
signal processing.
The
reason I am suggesting this is because it seems that the
most
confusing thing in this discussion is that the GetWave
functions
are not complete by themselves, they rely on Init
to
do part of the algorithms. But Init may do different
things
depending on whether there is a GetWave or not. Why
don't
we just have a function that does a complete LTI
analysis,
and another function that does a complete non-LTI
analysis?
Arpad
============================================================
From:
ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of fangyi_rao@xxxxxxxxxxx
Sent: Thursday, October 15, 2009 11:57 AM
To: dkirsanov@xxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: An AMI Overview
Hi,
Danil;
I
think we are on the same page. The fundamental problem is that
current AMI spec allows two usages of Init and GetWave as stated at the
end of
the BIRD.
Further
discussion identified that
two
different styles of modeling were possible and should be supported. In
the default case, the
AMI_Init
and AMI_Getwave calls represent filtering performed by sequential
stages of a
device, and
the
results should therefore be chained together. In the second case, the
AMI_Init and AMI_Getwave
calls
each represent the overall device. For example, the AMI_Init call
could
provide an LTI model
for
the device while the AMI_Getwave call provides a time-varying model.
In
this case, results from
the
AMI_Init and AMI_Getwave calls should be treated as independent.
The
first case obviously can’t support statistical simulation.
There
are different approaches to make the AMI standard to
support both time domain (pattern depend) and statistical simulations.
The
two-model approach suggested by Kumar is one of them. Walter and Arpad
prefer
to stay with one model by dropping support to the first case in AMI
since
practically no model of this usage exists.
I
want to take this opportunity to suggest another solution with
one model. In AMI we should separate the interface for time domain
simulation
from that for statistical by adding a third function named
GetImpulseForStatistical(). It takes impulses of victim and aggressors
and
returns modified impulses.
Regards,
Fangyi
Fangyi,
Could
you please clarify it? I agree that it might be reasonable
to put the linear part of the model in Init and non-linear part in
Getwave, so
that together they characterize the model (statistical
simulator uses
only the linear part, while the pattern-dependent always uses both).
But
I strongly disagree that inside one model Init and
GetWave can provide different approximations of the same
algorithm (i.e.
introducing double-counting), where statistical simulator uses Init and
pattern-dependent simulator uses GetWave. I believe this behavior
should be
prohibited, since it makes the flow more complicated, and we can easily
achieve
the same result providing two different models (or having internal
option to
switch the model between the statistical and non-linear mode).
If
we have this simple rule (non-linear simulator we always uses
Init and Getwave), the behavior of the EDA does not depend on the fact
whether
GetWave exists or not, and GetWaveExists flag becomes unnecessary (if
the
Simulator at some point figures out there is no GetWave, it just does
not use
it).
Are
we on the same page here?
Best,
Danil
Hi,
Kumar;
What
if a model wants to support non-linear time domain
simulation by GetWave and statistical simulation by returning a LTI
approximation in Init?
Thanks,
Fangyi
|
i agree..
if the model modifies the init it is the only thing it should be doing.
there should not be any getwave
--- On Wed, 10/14/09, Danil Kirsanov <dkirsanov@xxxxxxxxxx>
wrote:
From: Danil Kirsanov <dkirsanov@xxxxxxxxxx>
Subject: [ibis-macro] Re: An AMI Overview
To: ibis-macro@xxxxxxxxxxxxx
Date: Wednesday, October 14, 2009, 6:59 PM
Dear colleagues,
I would like to clarify one basic
principle of AMI modeling, hoping that all of us agree with it.
I believe that the model writer
should never do a double-counting: if he modified the channel impulse
response in Init() to model some effect, he should not model this
effect in Getwave(). So he cannot put the “true” model in GetWave() and
it’s linear approximation in Init(). If both types of behavior are
expected, there should be two models (or some internal flag that
changes the behavior of the model).
If this assumption is true,
statistical (linear) simulator always works with Init() function of the
model, while pattern-dependent (non-linear) simulator works with both
Init() and GetWave() and I do not see any necessity for Get_Wave_Exists
flag.
Best,
Danil
|
