RE: [SI-LIST] : Package Parasitics Modelling

tomda (tom_dagostino@mentorg.com)
Mon, 29 Mar 1999 13:11:18 -0800

If there was significant resistance between the input pin and the C
associated with the input protection devices it would show up in the input
VI curves. We don't see any significant R in series with the protection
devices when we make our measurement based models. The current in those
"diodes" can easily get to over 100 mA before the voltage across the device
is 1 volt.

Tom Dagostino

-----Original Message-----
From: Christian S. Rode [SMTP:csrode@mediaone.net]
Sent: Monday, March 29, 1999 11:16 AM
To: si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : Package Parasitics Modelling

A question about IBIS input models. I assume a good portion of the input
capacitance
of these models (C_comp) is associated with the input protection structures
and that
there can be significant resistance between that capacitance and the pad.
That's
not modeled in (earlier) IBIS models (and the EIA FAQ's "it's included
in the I-V characteristics" isn't relevant). 50 milliohms (or whatever)
for R_pkg will
give an unnaturally high-Q for the input model. What would be a range of
numbers for
R between the L and C? (I'm currently guessing 100 ohms)

Chris Rode

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