Subject: Re:

From: "Shaggy Gonzalez" <[email-masked]>
Date: Mon, 23 Nov 1998 15:50:29 PST

Hi ,
I generated an IBS Model for a cell which is an input buffer. Hence , it 
has only Power and Gnd Clamp information in the .ibs file.

1.Problem is that though the Gnnd Clamp is showing values from-2.5V to 
2.5V, the Power Clamp is showing from -2.5V to 0V only.Is it O.K.?

 2. All the max/min/typ values for Power Clmp table for all voltages 
between -2.5V to 0V are identical. Is that possible?When does it happen?
Bye
Shaggy

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From: Kellee Crisafulli <[email-masked]>
Date: Mon, 23 Nov 1998 16:54:44 -0800

I am paraphrasing your questions, hope I have it right.

Q:If the voltage range does not cover the 2Vcc to -Vcc range will the
model still work:
A: If a given simulation run enters the region for which
the V/I data is not defined the simulation results are going to
be different from simulator to simulator because the data was not defined.
If the simulation never enters this region than it probably won't matter
unless a simulator has trouble reach DC convergence.
For the Power Clamp, positive voltage is in the normal operating region
so the power clamp has no data in the normal operating region.  While
this may cause no problem if the value a 0V is 0 current and the simulator
does not extrapolate it will cause a problem if the simulator does
extrapolate.  
Bottom line -> this is a a potential problem.

Q:IS min/typ/max all the same going to cause a simulation problem?
A:Only if you care about min/max.  If not then the model is fine.
If so than you need to be aware that min/max conditions are not
represented.

>between -2.5V to 0V are identical. Is that possible?When does it happen?
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Have a great day....
Kellee Crisafulli at HyperLynx
SI,EMC,X-talk and IBIS tools for the Windows platform
E-mail: <mailto:[email-masked]>
web:    <http://www.hyperlynx.com>
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