[ibis-macro] Re: IBIS-AMI
- From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
- To: <msteinb@xxxxxxxxxx>, <scott@xxxxxxxxxxxxx>
- Date: Thu, 26 Jun 2008 14:00:02 -0400
It's worth pointing out an IBIS-AMI model actually has two models -
- the analog model in the .ibs file, and
- the algorithmic model pointed to by the .ibs file
IBIS-AMI analysis separates analysis of a link into two stages - network
characterization and link
analysis. The analog model is used for the former, while the algorithmic model
is used for the
latter.
When we talk about modeling PVT variation, it's worth considering how PVT
affects each type of model
separately. Modeling the effects of PVT on a transmitter's output stage or a
receiver's input stage
is well understood (it's what IBIS has been doing for years), while modeling
the effects of PVT on
equalization behavior is [relatively] new ground. I agree this is something we
should consider
standardizing, and I also agree that we need more experience in this area
before it makes sense to
try & put such standards in place.
Todd.
Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@xxxxxxxxxx
www.sisoft.com
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Mike
Steinberger
Sent: Tuesday, June 24, 2008 11:04 AM
To: scott@xxxxxxxxxxxxx
Cc: wkatz@xxxxxxxxxx; huangchunxing@xxxxxxxxxx; IBIS-ATM; guantao@xxxxxxxxxx
Subject: [ibis-macro] Re: IBIS-AMI
Scott-
Good question, indeed. A couple of thoughts:
First of all, while defining a standard way to support PVT may be a good
start, there are a number of other ways in which we all need to come to
a common understanding of what should go into a good IBIS AMI model. We
might tackle these subjects one at a time, but I would expect that the
net result is that we would be talking for a long time before we
produced a comprehensive result.
Secondly, I submit that, as an industry, we have less experience with
algorithmic modeling now than we did with electrical modeling at the
time IBIS was first created. Thus, it wouldn't hurt for us to get a bit
more collective experience with algorithmic modeling before we attempt
further standardization. We have what we need to move forward for the
time being, and we're all going to learn a lot over the coming year.
I suggest that once we've gained more experience, the next step would be
to have some presentations or white papers on what constitutes a good
IBIS AMI model. Such material would be immediately useful to both system
developers and model developers, and would position us to take the next
step in standardization.
Mike S.
Scott McMorrow wrote:
> Mike
>
> Huang's question is quite informative. For many years now, IBIS
> models have been required to carry PVT information in a standardized
> and well-documented way. With IBIS AMI there is no standard for
> including or documenting PVT variation.
>
> An interesting question is: should there be a standard way to include
> and/or document PVT variation and controls?
>
> Scott
>
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> (401) 284-1827 Business
> (401) 284-1840 Fax
>
> http://www.teraspeed.com
>
> TeraspeedR is the registered service mark of
> Teraspeed Consulting Group LLC
>
>
>
> Mike Steinberger wrote:
>> Huang-
>>
>> The short version to Walter's answer is that the IBIS AMI model maker
>> must incorporate the effects of Process/Temperature/Voltage (PVT)
>> into their model and then expose PVT as one or more input parameters
>> to the model. For example, SiSoft has delivered models that had PVT
>> as an explicit input parameter.
>>
>> This is one of a number of areas in which the IBIS AMI specification
>> makes it possible to write a good model, but does not define what a
>> good model is, much less force model makers to write good models. In
>> effect, we chose to depend on system developers such as yourself to
>> let us know what you need to see in a model in order to consider it
>> to be acceptable. What you've in effect said is that you expect a
>> proper model to include the effects of PVT, and that's a perfectly
>> reasonable expectation that any competent model maker should be able
>> to satisfy.
>>
>> I can offer a statement of what I believe constitutes a high quality
>> IBIS AMI model package, and I will if you wish. What's really
>> important, however, is for system developers to explicitly state
>> their expectations. (Golden Rule of Business: He who has the gold
>> makes the rules.)
>>
>> Hope this helps.
>> Mike S.
>>
>> Walter Katz wrote:
>>>
>>> Huang,
>>>
>>> IBIS-AMI models are controlled by parameters that have various
>>> solution space capabilities. These solution space capabilities are
>>> used to control the configuration of the Tx/Rx model (e.g. Tap
>>> coefficients, and peaking filter selection). The solution space of a
>>> parameter is controlled by its "Format". "Format" can be:
>>>
>>> * A single Value
>>> * A Range
>>> * A range with a specific number of Steps
>>> * A range with a specific Increment
>>> * A List of values
>>> * A Table
>>> * A Gaussian distribution
>>> * A Dual-Dirac distribution
>>> * A DjRj distribution
>>> * A Corner
>>>
>>> The "Corner" format specifies a <typ value>, <slow value> and <fast
>>> value>. These values are intended to be used in conjunction with the
>>> corresponding <typ>, <min> and <max> values of the analog part of
>>> the IBIS model.
>>>
>>> This is described in page three of BIRD 104.1
>>>
>>> Regards,
>>>
>>> Walter
>>>
>>> Walter Katz
>>>
>>> Signal Integrity Software, Inc.
>>>
>>> (303) 449-2308
>>>
>>> -----Original Message-----
>>> *From:* ibis-macro-bounce@xxxxxxxxxxxxx
>>> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]*On Behalf Of *Huang chunxing
>>> *Sent:* Tuesday, June 24, 2008 2:06 AM
>>> *To:* IBIS-ATM
>>> *Cc:* guantao@xxxxxxxxxx
>>> *Subject:* [ibis-macro] IBIS-AMI
>>>
>>> Hi AMI experts,
>>>
>>> Does IBIS-AMI support modeling Serdes with different cases,
>>>
>>> like, typical case, Best case and worst case.
>>>
>>> This question may look some idiotic. But I hope
>>>
>>> some experts here may give me a definite answer
>>>
>>> and how to arrange these models in IBIS according to AMI specification.
>>>
>>> Thanks!
>>>
>>> Regards,
>>>
>>> Huang
>>> HUAWEI TECHNOLOGIES CO.,LTD. huawei_logo
>>>
>>>
>>> Address: Huawei Industrial Base
>>> Bantian Longgang
>>> Shenzhen 518129, P.R.China
>>> Tel: +86 755 89651163
>>> Fax: +86 755 89652294
>>> E-mail: huangchunxing@xxxxxxxxxx <mailto:huangchunxing@xxxxxxxxxx>
>>> www.huawei.com <http://www.huawei.com>
>>>
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>>
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