RE: [IBIS-Users] RE: [IBIS] input signal for model usage

Fabio,
 
You are correct on the first one, and almost correct
on the second.
 
1)  The edge rate of the stimulus to an IBIS model will
not change its output edge rate, but it will shift it,
depending on how the tool implements the threshold on
the stimulus input of the IBIS model.  This is not related
to the IBIS Vinh and Vinl (or related) parameters.  The
IBIS specification doesn't say anything about how the
threshold of the input stimulus should be detected by 
the IBIS model implementation.
 
2)  If you clock the IBIS model faster than the V-t curve
can handle it you would need to make a new model, but not
only a new model, but also a new chip.  The fact that a
V-t curve goes only so fast indicates that the chip itself
can't go faster.  So no matter how hard you try to make a
new set of V-t curves, you won't succeed unless you redesign
the chip itself...
 
Arpad
=============================================================

________________________________

From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Fabio BRINA
Sent: Tuesday, March 17, 2009 8:00 AM
To: 'Muniswara Reddy Vorugu'; ibis-users@server.eda.org;
ibis@server.eda.org
Subject: RE: [IBIS-Users] RE: [IBIS] input signal for model usage


 
Thank you Muniswar,
 
 could you confirm (or correct) these propositions? :
 
 - if I change only rise/fall slew at the input (A_in as you say)
   the Output response is the same. (could be only a little shift time
in the Output?)
 
 - if I change the input clock frequency (fck), the Output response is
correct
   until fck is under the frequency used in the V-T tables generation.
   (if I want to use an higher clock frequency, I have to generate a new
model
    with differents V-T tables)
 
 are that right?
 
 many thanks,
 
 Fabio
 
 

________________________________

From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Muniswara Reddy
Vorugu
Sent: Tuesday, March 17, 2009 12:00 PM
To: Fabio BRINA; ibis-users@server.eda.org; ibis@server.eda.org
Subject: [IBIS-Users] RE: [IBIS] input signal for model usage



Hi,

The OUTPUT of I/O ( IBIS model)  does not depend on the Rise/Fall slew
at the input of I/O ( say A_in ).

 

If you mean. Can you have different  LOW/HIGH duration? 

You can give different clock/pulse frequency, but there is an upper
limit of the clock.

The upper limit of the clock frequency is limited by the duration of the
V-T tables/Ramp time.

 

Thanks,

Muniswar

 

From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Fabio
BRINA
Sent: Tuesday, March 17, 2009 3:55 PM
To: ibis-users@eda.org; ibis@eda.org
Subject: [IBIS] input signal for model usage

 

Hello IBIS experts, 

 

 Once an IBIS model has been created, can be used in different Input
speeds?

 

 In other words: if I consider an I/O model, Can I use every input Pulse
with

 several rise/fall time Or I have to use only the same pulse used in the


 model creations?

 

I hope is clear what I mean.

 

Thanks,

Fabio

 

 


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