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J. Maier, A. Steininger:
"Efficient Metastability Characterization for Schmitt-Triggers";
Talk: 25th IEEE International Symposium on Asynchronous Circuits and Systems (ASYNC 2019), Hirosaki, Japan; 2019-05-12 - 2019-05-15; in: "2019 25th IEEE International Symposium on Asynchronous Circuits and Systems (ASYNC)", (2019), ISBN: 978-1-5386-4747-9; 124 - 133.

Despite their attractiveness as metastability fil-
ters, Schmitt-Triggers can suffer from metastability themselves.
Therefore, in the selection or construction of a suitable Schmitt-
Trigger implementation, it is a necessity to accurately determine
the metastable behavior. Only then one is able to compare
different designs and thus guide proper optimizations, and only
then one can assess the potential for residual metastable upsets.
However, while the state of the art provides a lot of research
and practical characterization approaches for flip-flops, compar-
atively little is known about Schmitt-Trigger characterization.
Unlike the flip-flop with its single metastable point, the Schmitt-
Trigger exhibits a whole range of metastable points depending
on the input voltage. Thus the task of characterization gets much
more challenging.
In this paper we present different approaches to determine
the metastable behavior of Schmitt-Triggers using novel methods
and mechanisms. We compare their accuracy and runtime by
applying them to three common circuit implementations. The
achieved results are then used to reason about the metastable
behavior of the chosen designs which turns out to be problematic
in some cases. Overall the approaches proposed in this paper are
generic and can be extended beyond the Schmitt-Trigger, i.e., to
efficiently characterize metastable states in other circuits as well.

Schmitt Trigger, Metastability Characterization, SPICE

http://dx.doi.org/10.1109/ASYNC.2019.00024