RE: [IBIS-Users] Clamp graphs issue.

From: Tom Dagostino <tom_at_.....>
Date: Thu Oct 22 2009 - 09:21:53 PDT
Kobi

 

Is there a series resistor model in the file that could be the termination
you are looking for?  Many times we use the series resistor feature of IBIS
to model input terminations.  This works much better than putting those
characteristics in the ground or power clamp.  In many cases the termination
can float but with the termination imbedded in the clamp curve you are stuck
with a fixed set of IV characteristics.

 

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065

503-430-1285 FAX
tom@teraspeed.com
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827 

 

From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Kobi Pinhas
Sent: Thursday, October 22, 2009 8:57 AM
To: ibis-users@server.eda.org
Subject: [IBIS-Users] Clamp graphs issue.

 

Hi all.

I have some conceptual issue.

The next graph represents gnd clamp of an input model of a memory with 120
ohm ODT

This is model of a famous company which I download:



 

I don't understand how it is possible that the current is zero fot V> -0.5V.

The meaning of ODT is resistor that connected from the input to the gnd.

So for this range (when V>-0.5V) I was expecting to see linear current with
a slope that equal to the resistor.

 

For example when I simulated gnd clamp of an input buffer with 50 ohm ODT I
received the next plot:



 

You can see that the plot is liner for V> -0.5V as expected.

I looked in a lot of ibis file and I never saw common behavior.

So I guess that maybe I am doing something wrong.

 

I will be glad to hear your comments.

 

Thanks a lot.

 

Kobi.


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Received on Thu Oct 22 09:27:12 2009

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