[ibis-macro] Re: Truth table taken to the next level

  • From: Scott McMorrow <scott@xxxxxxxxxxxxx>
  • To: kwillis@xxxxxxxxxxx
  • Date: Wed, 28 Apr 2010 11:33:07 -0400

Title: Truth table taken to the next level

Having a number of modeling and simulation options available does not preclude a model developer from doing just exactly what you say - creating models that support the simplest of flows.  As a designer, an architect and a model maker, I will always opt for maximum flexibility in the specification that supports current and future devices.  Teraspeed Consulting will always support the maximum flexibility in the IBIS-AMI specification.



Ken Willis wrote:

Hi Arpad,


My apologies for missing the meeting yesterday, I just returned from vacation and was digging out.


I am concerned that we are going in entirely the wrong direction with this, in that it is becoming far too EDA-centric and not IP supplier-centric enough. And I think the latter is what we need to focus on if we are ever to have a robust pool of Serdes models available for the SI engineering community to use.


I have spoken with a lot of Serdes IP suppliers, and have never heard any mention of supporting statistical or LTI TD or non-LTI TD or partial statistical or full non-LTI TD or any other specific kind of analysis. What I hear is things much more like this:


- What IBIS-AMI API do I need to use for my Serdes Tx / Rx? I want to use the most straightforward approach to model my filter.

- Does the filtering in my Serdes IO do a one-time adaptation to my channel? If it does I will use the modified impulse response approach, since that is simplest.

- Does my filtering do real-time dynamic kind of adaptation? If it does, I will need to use the GetWave approach and process waveforms directly.


This is admittedly a little over-simplified, but I think is basically on target. I think we would do much better to think more along these lines rather than add all the complexity I see in these tables below. To be successful, I think we need to keep this as simple as possible, and enable models to be developed. I would even go as far as to say that the most practical approach for a given Serdes IO would be to use either the impulse response or GetWave API, but not both together.


I would be interested to hear opinions on these ideas from the people on this list.




Ken Willis

Sigrity, Inc.




From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Wednesday, April 28, 2010 1:57 AM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Truth table taken to the next level


Dear AMI experts,
I cleaned up the spreadsheet with the truth table that we discussed
in our ATM meeting today.  It looks like this now:

Picture (Device Independent Bitmap)

I hope I got it right this time.

The next thing I would like to do is to extend this table
and spell out how these conditions can be applied to Tx
and Rx independently.  In other words, I don't believe
that our intent was to require these Booleans to be the
same for both Tx and Rx.  But how many combinations are

We have four (4) combinations per buffer, and we have two
buffers, which could theoretically allow 4^2 = 16 total
possibilities.  Are they all valid?

Picture (Device Independent Bitmap)



Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax


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