Runt pulse
In digital circuits, a
runt pulse is a narrow
pulse that,
due to non-zero rise and fall times of the signal, does not reach a valid
high or low level. A runt pulse may occur when switching between
asynchronous clocks; or as the result of a
race condition in which a signal takes two separate paths through a circuit, which may have different delays, and is then recombined to form a
glitch; or when the output of a
flip-flop becomes
metastable.
Some oscilloscopes provide a method for triggering on runt pulses. The oscilloscope triggers when the signal crosses one of two voltage thresholds, but not both.