[ibis-macro] Re: AMI-init should pass modified IR to getwave....
- From: Taranjit Kukal <kukal@xxxxxxxxxxx>
- To: "wkatz@xxxxxxxxxx" <wkatz@xxxxxxxxxx>, "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>
- Date: Thu, 14 Jun 2012 17:51:42 +0530
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 --> Convolve-with-Tx-getwave o/p --> 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]<mailto:[mailto:wkatz@xxxxxxxxxx]>
Sent: Thursday, June 14, 2012 02:25 PM
To: Taranjit Kukal; 'IBIS-ATM'
<ibis-macro@xxxxxxxxxxxxx<mailto: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>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:[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@01CD4A53.52DCDE80]
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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