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

  • From: Ambrish Varma <ambrishv@xxxxxxxxxxx>
  • To: IBIS-ATM <ibis-macro@xxxxxxxxxxxxx>
  • Date: Tue, 20 Apr 2010 20:24:10 -0700

Hi Arpad,
Pardon me for my choice of words - that's what happens when there is food in 
front of you.
I had no intention of spelling out the future - but simply wanted to list what 
the intent of the original spec was - simply my opinion and judgment.

The fact that a model has effective double counting by modifying the channel 
impulse response in the Init and then model this same effect in getwave will of 
course have an implication on the flow issue that Walter brought up. Why else 
would you worry about "what goes from one Init function into
the next Init function"  if one or both Use_Init_Output flags are false?

Thanks,
Ambrish.



________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, April 20, 2010 8:39 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

Ambrish,

How can you make such a bold statement about the future:
"However for non-linear models, there will be no equalization (that 
approximates the equalization in the GetWave) in the Init function..."?
It makes me feel that I should come to you for advise on
how to make my investments... :-)

I think this is exactly what some of us disagrees with you.
Walter may even come back saying that they have already made
models like that, but I will let him speak for himself...

From this I am starting to get the impression that we are
really not talking about a flow issue here, but the question
of what the intent was between the Init and GetWave functions
regarding supporting LTI and non-LTI devices in the same model.

I thought this question was settled before in my message to
Ken (included below).  Why are we still dwelling on it?

Arpad
================================================================


-----Original Message-----
From: Muranyi, Arpad
Sent: Wednesday, March 31, 2010 12:35 AM
To: 'IBIS-ATM'
Subject: Comment on Sigrity's presentation

Ken,

I would like to make a comment on slide 3 of the presentation
you gave us in the ATM teleconference a week ago and the
discussion that followed.

http://www.vhdl.org/pub/ibis/macromodel_wip/archive/20100323/kenwillis/Sigrity%20AMI%20BIRD%20Feedback/Sigrity_AMI_BIRD_fback.pdf

If I understood the discussion correctly, you and Kumar are
concerned that one model could produce different results
when only its Init functions are used vs. when its GetWave
functions are also used.  The discussion between you and Todd
ended in a disagreement.

However, it just occurred to me that the AMI portion of the
IBIS 5.0 specification already talks about the possibility
of having two types of analysis paths, one that only uses
the Init functions (for LTI systems), and another that also
involves the GetWave function when non-LTI effects are present.
This is found in Section 10, 2.1 and 2.2 in the specification.

Doesn't this close the discussion we had in the meeting when
you were presenting in a sense that you are challenging an
intent that is already clearly spelled out in the specification?

Thanks,

Arpad
=================================================================


________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Ambrish Varma
Sent: Tuesday, April 20, 2010 7:08 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference
Hi Arpad,
Sorry - I did mean Nonlinear, and/or Time Variant.
Well, there is a link. For a linear model, there will be no getwave, so slide 5 
will correctly represent the scenario. However for non-linear models, there 
will be no equalization (that approximates the equalization in the GetWave) in 
the Init function, as such Tx (and RX) Use_Init_Output will always be true. 
This would also mean that these models (with Getwave) would not be suitable for 
Stateye type simulations.

Only models that would like to perform both Stateye type simulation as well as 
(meaningful) Time Domain simulation via the same model will have issues as a 
straight path from Tx_Init to Rx_Init is needed for Stateye type sim.

In my opinion, if we follow the simple rule set out by the spec, a lot of the 
confusion will automatically be resolved.

Please let me know if I was clear enough. :)
Thanks,
Ambrish.

________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, April 20, 2010 6:38 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

Ambrish,

I think you meant "Time-variant" in a few places where you wrote
"Time-invariant"... but aside from that I am not sure what this
has to do with Walter's comment about what goes into Rx_Init.
Can you explain how these two topics are related?

Thanks,

Arpad
==================================================================

________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Ambrish Varma
Sent: Tuesday, April 20, 2010 5:32 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference
Hi Arpad,
The spec is very clear in delineating between Linear, Time-invariant model and 
Nonlinear, and /or Time-invariant models. (section 2, chapter 10). It was 
expected that a non linear/time-invariant model would not try and model an 
approximation of the same algorithm in the Init function. Also, a linear model 
would not have a getwave function.

Thanks,
Ambrish.

________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Muranyi, Arpad
Sent: Tuesday, April 20, 2010 6:08 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

Walter,

Thanks for your feedback.  I think you just made us discover another
discrepancy in the spec.  Contrast what you quoted with this from
the IBIS specification:

[cid:image001.jpg@01CAE0DF.F10F48C0]
[cid:image002.jpg@01CAE0DF.F10F48C0]

What do you suggest we should do about this?

Arpad
========================================================================

________________________________
From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Tuesday, April 20, 2010 4:27 PM
To: Muranyi, Arpad; IBIS-ATM
Subject: RE: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference
Arpad,

In the IBIS 5.0 specification:


|               Use_Init_Output:

|

|               Use_Init_Output is of usage Info and type Boolean.  When

|               Use_Init_Output is set to "True", the EDA tool is

|               instructed to use the output impulse response from the

|               AMI_Init function when creating the input waveform

|               presented to the AMI_Getwave function.

|

|               If the Reserved Parameter, Use_Init_Output, is set to

|               "False", EDA tools will use the original (unfiltered)

|               impulse response of the channel when creating the input

|               waveform presented to the AMI_Getwave function.

|

|               The algorithmic model is expected to modify the waveform in

|               place.

|

|               Use_Init_Output is optional. The default value for this

|               parameter is "True".

|
|               If Use_Init_Output is False, GetWave_Exists must be True.

In what was agreed to in November, the input the Rx_Init was always hAC(t) X 
hTEI(t).
In what you presented this week, the input to Rx_Init is either hAC(t) or 
hAC(t) X hTEI(t), depending on the value of Tx Use_init_Output. I believe based 
on the IBIS 5.0 specification above that the November flow is correct and the 
Spec. correction flow that you presented this week is incorrect.

Walter


Walter Katz

303.449-2308

Mobile 720.333-1107

wkatz@xxxxxxxxxx

www.sisoft.com

-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx 
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Muranyi, Arpad
Sent: Tuesday, April 20, 2010 12:48 AM
To: IBIS-ATM
Subject: [ibis-macro] Re: AMI_Flows_6.pdf for today's ATM teleconference

Here is the AMI_Flows_6.pdf file once again.  I made
the changes which were suggested to me in the last ATM
meeting.  This flow includes only the correction we
wanted to make on the existing spec flow.

I am not sure what the decision was about the last two
slides which deal with the Rx pad waveform.  Did we
say we would delete these slides altogether and not
address this capability in this BIRD?  As far as I can
tell, we can't achieve this flow without deconvolution...

Please familiarize yourselves with these slides, because
I would like to achieve closure on this flow in the ATM
teleconference tomorrow.  Comments are welcome before or
at the meeting.

Thanks,

Arpad
=========================================================

________________________________
From: Muranyi, Arpad
Sent: Tuesday, April 13, 2010 1:39 PM
To: 'IBIS-ATM'
Subject: AMI_Flows_6.pdf for today's ATM teleconference
For those who are unable to join the meeting via
LiveMeeting, here is a new flow diagram to aid the
discussion on the subject.

Arpad
==================================================

JPEG image

JPEG image

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