[IBIS-Users] Input ESD Structures


Subject: [IBIS-Users] Input ESD Structures
From: Timothy Coyle (Timothy.Coyle@nsc.com)
Date: Mon Apr 22 2002 - 11:50:40 PDT


Hello,
When I get a SPICE netlist from the design team to do a spi2ibis
translation, the ESD structures have ideal diodes (no resistance) which
leads to kAmps in my
power and ground clamp curves. So I put a series resistor of 1-3 Ohms on
the input of the ESD pad (and sometimes the ground node of the ESD pad) to
try to limit
the current. While this approach works, my simulated data does not match
up with data taken from the bench. The lab data at one point is 4.3mA and
the simulated
data at the same point is 160uA for a ground clamp curve. Changing the
resistor value doesn't give me the right current either. Does anyone have
any
comments/suggestions on this approach?

Also, I'm wondering what type of affect on my input model the magnitudes
of my power and ground clamp curves have. Does it matter to a simulator if
the ground clamp
current is 4.3mA or 160uA? It seems the most important parameter for an
input model is Ccomp. Has anyone done any work on this they would like to
share?

Many thanks again to those who respond,

Tim

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