Superconductive A/D converters

A number of superconductive A/D (analog/digital) converter designs that show promise for superiority in high-bandwidth or high-resolution applications are known. On the high-resolution side, counting-type converters appear quite attractive. Voltage-to-frequency and tracking A/D converters are reviewed in this category. On the ultra-high-bandwidth side (greater than about 1 GHz) the parallel-type A/D coverters seem to be advantageous. A number of parallel periodic-threshold A/D converters that have been attempted over the years as well as a fully parallel (2 exp N - 1 comparators) A/D converter are reviewed.