[IBIS-Users] Non - Monotonicity of the data


Subject: [IBIS-Users] Non - Monotonicity of the data
From: Anshuli Goel (anshuli@ti.com)
Date: Thu May 08 2003 - 20:39:42 PDT


Hello Experts

I am trying to do IBIS model generation of one o/p tristate
buffer
susing s2ibis2.
Beyond the rail simulations I am getting follwoing error
"_____________________________
"* ERROR * [SIM:0] Current (5.12686e+38) of voltage source
VOUTS2I
exceeds CURMAX (1)
* ERROR * [SIM:1] Current (-5.12686e+38) of voltage source
VSS exceeds
 -CURMAX (-1)
_____________________________

Reson of this as far as I understand is that after one
particular
voltage the clamp diode start working and give these
errors.

Somewhere I read
"Semiconductor device models may not be well behaved over
these ranges,
so it is acceptable to lessen the actual sweep range and
then use linear
extrapolation to get to the required endpoints. However,
the simulation
sweep range must be enough to forward bias any
ESD/protection diodes or
the diodes intrinsic to the output transistor
structures."

I also want to do linear extrapolation for the buffer in
question. What
is the way to do the extrapolation ?

One more thing is that I get non-monotonic data in Power
clamp curve.
How can I get rid of this non-monotonicity ?

Regards
Anshuli Goel

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