[ibis-macro] Re: Samples_per_bit question

Scott McMorrow
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I think we all agree that to require a certain samples_per_bit for the model to work is not good. We can deal with this at a tool level and not put anything in the spec as this will most definitely give it more prominence. In other words, model makers will feel compelled to ‘do something’ with this parameter.

My 2 cents.

 

-Ambrish.

 

 

	Ambrish Varma   |  Member of Consulting Staff
	P: 978.262.6431   www.cadence.com

 

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From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Dmitriev-Zdorov, Vladimir
Sent: Wednesday, July 20, 2011 4:25 PM
To: msteinb@xxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Samples_per_bit question

 

Agree,

 

We also encountered with such models. The problem is when something does not work it is difficult to guess what’s the problem and even after that it takes several tries to find an appropriate parameter.

 

Vladimir

 

 

From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Mike Steinberger
Sent: Wednesday, July 20, 2011 2:18 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Samples_per_bit question

 

Kumar-

We agree with you in principle, and on the two occasions (years ago now) when we encountered a model that required a specific number of samples per bit, we did ask the model developers to make their models more general. Unfortunately, neither the IBIS spec nor any customer required them to support an arbitrary number of samples per bit, so the model developers did not accept our suggestion.

These models have now been in widespread use for several years. Given that, how should we handle the problem? To date, the solution we've proposed is the Samples_per_bit reserved parameter.

Thanks.
Mike S.

On 07/20/2011 03:07 PM, ckumar wrote:

the ami model should treat the waveforms as continuous. They should

resample it inside the model for their requirements.

Requiring specific sample size is an unnecessary constraint. 

On Wed, 20 Jul 2011 19:44:03 +0000, "Muranyi, Arpad"

<Arpad_Muranyi@xxxxxxxxxx> wrote:

Hello everyone,

I recall that we asked Walter to remove the proposed Samples_per_bit

Reserved AMI parameter from BIRD 121, which he did in BIRD 121.1.

What I don't remember is whether we made this request because we

decided that we didn't want/need this reserved parameter in the AMI

specification at all, or whether we just didn't want to propose this

in BIRD 121, since it seemed unrelated to the rest of the BIRD 121

content.  Could someone please refresh my memory on that?

The reason I am asking is because just recently I ran across a couple

of AMI models which only work at certain samples per bit settings

but there was no documentation that I am aware of that came with the

model that stated that.

I am not sure if this was done intentionally by the model's authors,

but it seems that a required reserved parameter would at least serve

as a reminder to the model makers to document the value at which

their model works, if not remind them to write models that work at

any reasonable samples per bit values.

Based on this experience I tend to feel that a required, and reserved

parameter for Samples_per_bit would be very useful in the AMI spec...

Comments, suggestions are welcome.

Thanks,

Arpad

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