RE: [SI-LIST] : Schottky diode termination

Bob Perlman (bobperl@shell14.ba.best.com)
Fri, 30 Oct 1998 10:52:52 +0000

Hi -

I think Bob Davis has done a great job of clearly articulating the
reasons why IC I/O protection diodes should not be relied upon as
terminations.

The recent advent of IBIS models is a wonderful thing, but there's at
least one drawback: many of these models contain I/V curves for
clamp diodes. It's all too easy to throw together a simulation, see
an acceptable result, and forego resistive termination, never
realizing that it's the (poorly-characterized, vendor-dependent)
clamp diodes that have cleaned up the signal. At any rate, it's
something to watch out for.

Bob Perlman
Cambrian Design Works

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