[SI-LIST] Your blog post: Four Things That Drove Me Nuts About IBIS 5.1
- From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Fri, 26 Oct 2012 09:56:48 -0400 (EDT)
Colin,
Your paper "Explore the SERDES design space using the IBIS AMI channel
simulation flow" and blog entries redefine pre-existing terms, which I
think is going to increase confusion, not reduce it. If you want to
clarify IBIS 5.1 flows, I think you should stick with the terminology the
committee already uses.
There are, indeed, 4 possible combinations of the parameters
"Init_Returns_Impulse" and "Getwave_Exists", but only three possible model
states, because invalid states don't count.
Your paper redefines the word "Case" and proposes independent case
numbering for Statistical and Time-Domain analysis. That's not how the
spec works. There are 3 legal states for an AMI model, thus 9 possible
combinations (cases) of TX and RX models. Each case is completely defined
for both Statistical and Time-Domain analysis. That makes 9 flows, not
32.
This was laid out in the July 2010 presentation "IBIS-AMI Flows", which is
on the IBIS-ATM committee website at http://tinyurl.com/28bj9nm. This is
where the equations for the 9 different AMI flows in IBIS 5.1 were
originally spelled out. The text on pages 158-162 of the IBIS 5.1 spec
describes how these equations are realized for Statistical and Time-Domain
simulations in step by step fashion. If you choose to create new material
that presents IBIS-AMI flows, I think you should be consistent with the
committee's prior work and the written spec.
One area that's probably worthy of new discussion is how we name the
different AMI model states in a user-friendly manner. Those of us who are
close to IBIS have become accustomed to the definitions
Init = Initialization and linear processing,
Getwave = Nonlinear and time-varying waveform processing
And thus tend to refer to models as "Init-only", "Getwave-only" and "Dual
or Advanced". If you think associating "LTI" with "Init" and "NLTV" with
"Getwave" will help reduce confusion, then I think you should propose an
IBIS BIRD to that effect. I'll even help you write it.
Todd.
Todd Westerhoff
VP, Software Products
Signal Integrity Software Inc. . <http://www.sisoft.com/> www.sisoft.com
6 Clock Tower Place . Suite 250 . Maynard, MA 01754
( <callto:978%29%20461-0449> 978) 461-0449 x24 .
<mailto:twesterh@xxxxxxxxxx> twesterh@xxxxxxxxxx
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-Sidewalk Prophets
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