[ibis-macro] Re: AMI-init should pass modified IR to getwave....

  • From: "Walter Katz" <wkatz@xxxxxxxxxx>
  • To: "'ckumar'" <ckumar@xxxxxxxxxxx>
  • Date: Thu, 14 Jun 2012 08:16:37 -0400 (EDT)

All,

I believe that what Kumar is saying is that there is no need for a Tx or Rx 
to output Init Impulse Response that is to be combined with the output of 
GetWave or the input of Rx GetWave. So in this respect I believe Kumar 
agrees with me that there is no need for a second Impulse Response output of 
Init in a model that supports both Init Statistical and GetWave time domain 
processing.

Of course I have always objected, and will continue to object to requiring 
that model makers have separate AMI models for Init statistical processing 
and GetWave time domain processing. Such a change would deprecate an 
important feature that many models use today and is allowed in the original 
IBIS 5.0 specification.

Bottom line: Can anyone can express a compelling reason for Init returning 
two impulse responses (other than there may be some model makers that are 
incapable of implementing the Overlap -save method described in 
http://en.wikipedia.org/wiki/Overlap%E2%80%93save_method)?

Walter
.

-----Original Message-----
From: ckumar [mailto:ckumar@xxxxxxxxxxx]
Sent: Thursday, June 14, 2012 8:00 AM
To: wkatz@xxxxxxxxxx
Cc: Taranjit Kukal; ibis-macro@xxxxxxxxxxxxx
Subject: Re: [ibis-macro] Re: AMI-init should pass modified IR to 
getwave....

my views and original intent  are when a model implements getwave it should 
closely approximate the real device . ie. it should input waveform as a 
continuous waveform and do what is necessary. Real devices do not do 
anything to impulse response because it is an analytic  construct not 
available naturally.

If statistical processing is desired a separate init model should do. This 
is analogous in circuit modeling where we have a analytic/semi analytic 
behavior model and more "real" and complex? silicon level model.


On Thu, 14 Jun 2012 07:35:40 -0400 (EDT), "Walter Katz" <wkatz@xxxxxxxxxx>
wrote:
> Kukal,
>
>
>
> So you want to make it easy for the model makers by having Init return
two
> impulse responses, the current ones that is used for the “Init”
flow,
> and a
> second one that the EDA tool would presumably use in the following way:
>
> For Tx, the EDA tool would convolve this second impulse response with
the
> output of Tx GetWave.
>
> For Rx, the EDA tool would convolve this second impulse response with
the
> input to Rx GetWave.
>
>
>
> 1.       Please confirm that this is what you propose to do with the
> second
> impulse response that you want the Init function to return.
>
> 2.       And if you do confirm this, cannot the model maker pass this
> Impulse Response to its GetWave, and have its GetWave do this
convolution.
>
>
>
> Assume you confirm 1., then what is the compelling reason for us to
change
> the outputs of Init to make it simpler for a model maker to eliminate
> a trivial convolution that he can do in his GetWave function?
>
>
>
> Walter
>
>
>
>
>
> From: Taranjit Kukal [mailto:kukal@xxxxxxxxxxx]
> Sent: Thursday, June 14, 2012 6:53 AM
> To: wkatz@xxxxxxxxxx; 'ibis-macro@xxxxxxxxxxxxx'
> Subject: Re: [ibis-macro] AMI-init should pass modified IR to
getwave....
>
>
>
> Hi Walter,
> I meant model-makers who want to use both init and getwave in
conjunction
> for transient flow v/s those who want to do everything in getwave.
>
> Apologize if this statement was confusing..
>
> Rgds
>
>
>
> From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
> Sent: Thursday, June 14, 2012 02:25 PM
> To: Taranjit Kukal; 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx>
> Subject: RE: [ibis-macro] AMI-init should pass modified IR to
getwave....
>
>
> Kukal,
>
>
>
> Who are “those” in you statement “those who want to leverage init
as
> complement to getwave and those who want to keep statistical-flow
> purely

> independent.”
>
>
>
> Walter
>
>
>
> From: ibis-macro-bounce@xxxxxxxxxxxxx
> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Taranjit Kukal
> Sent: Thursday, June 14, 2012 2:04 AM
> To: 'IBIS-ATM'
> Subject: [ibis-macro] AMI-init should pass modified IR to getwave....
>
>
>
> Hi All,
>
> When I was implementing AMI model, I found a situation where it was
> important that Rx ami_init needed to pass modified-IR to getwave
function.
>
> Reason was that Chip-RDL-routing was available as Impulse-Responses.
>
> Removal for “Use_Init_Output” to make Statistical-flow independent
of
> Transient-flow,  is going to break the original intent where init and
> getwave were supposed to work in conjunction with each other handling
> linear and non-linear filtering portions respectively (as shown below)
>
>
>
> cid:image001.png@01CD49C5.F040DCA0
>
>
>
> I would go back to Arpad’s suggestion (year 2010) for having two
> Impulse-responses coming out of ami_init
>
> -          One that goes to EDA tool for statistical flow
>
> -          One that gets passed to getwave to allow splitting of
> modeling-effort across init and getwave and make things easy for
> linear filters.
>
>
>
> BIRD120 was brought up that deprecates use of “use_init_output” with
a
> view
> to keep statistical and time-domain simulations independent. But as I
> think more, we need to allow both capabilities. It absolutely does not
> make sense to implement simple linear filters within getwave when we
> can convolute the filter-IR with channel-IR. We should take all steps
> to make modeling
easy
> and ensure enough flexibility.
>
>
>
> This way, we cover both the scenarios – those who want to leverage
init
> as
> complement to getwave and those who want to keep statistical-flow
> purely

> independent. Since this does not bring any disadvantage, I strongly
> feel

> that we all re-consider outputting two modified-IRs out of init
> function – one for statistical-flow and another one to complement
> getwave
filtering.
>
>
>
>
>
> Rgds
>
> ..kukal
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