[ibis-macro] Re: AMI-init should pass modified IR to getwave....
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: "'Taranjit Kukal'" <kukal@xxxxxxxxxxx>, <ibis-macro@xxxxxxxxxxxxx>
- Date: Thu, 14 Jun 2012 08:39:12 -0400 (EDT)
Kukal,
The following is off course invalid if Tx-getwave o/p is not LTI. We have
litigated this already.
Tx-init IR-> Rx-init IR à Convolve-with-Tx-getwave o/p à Rx-getwave….
Walter
From: Taranjit Kukal [mailto:kukal@xxxxxxxxxxx]
Sent: Thursday, June 14, 2012 8:22 AM
To: wkatz@xxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] AMI-init should pass modified IR to getwave....
Hi Walter,
The flow-diagram in my 1st email should make clear how the IR gets handled
by EDA-tool (I see it is different from what u wrote – Is this not the new
recommended flow?):
Tx-init IR-> Rx-init IR à Convolve-with-Tx-getwave o/p à Rx-getwave….
Coming to your second question on getwave doing convolution of filter-IR
with waveform, here are few points:
1. IR flow from Tx to Rx through init-function modifications breaks –
assuming the new recommended flow is what I drew.
2. Model-maker anyways has to convolute two IRs in init for
statistical flow or to get initial estimates of taps; so why double the
effort of convoluting again in getwave .
Again, it is about not taking away the flexibility of modeling….
Coming to Kumar’s point on expressing the real devices, I think it depends
on level of abstraction – the model could operate at various level of
abstractions – depending on need.
Rgds
..kukal
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Thursday, June 14, 2012 5:06 PM
To: Taranjit Kukal; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] AMI-init should pass modified IR to getwave....
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
Other related posts:
