The level-crossing A/D converter is based on level-crossing sampling as opposed to the conventional time sampled A/D converters.
The signal is sampled when it crosses a quantization level, when for each
sample the sampling time and level crossed are stored. Thus, the time intervals between sampling instants are unevently distributed, but the amplitude error in the sampling instant is minimized.
Critical components in the system design are the comparator that detects the level crossing, as well as the time measuring unit. The research has focused on the design of low power time-continous comparators with stable propagation time.