All-MOS charge-redistribution analog-to-digital conversion techniques. II

Abstract

For pt.I see ibid., vol.SC-10, no.6, p.371-9 (1975). Describes techniques for performing A/D conversion compatibly with standard single-channel MOS technology. This second paper describes a two-capacitor successive approximation technique which, in contrast to the first, requires considerably less die area, is inherently monotonic in the presence of capacitor ratio errors, and which operates at somewhat lower conversion rate. Factors affecting accuracy and conversion rate are considered analytically. Experimental results from a monolithic prototype are presented; a resolution of eight bits was achieved with an A/D conversion time of 100 /spl mu/s. Used as a D/A convertor, a settling time of 12.5 /spl mu/s was achieved. The estimated total die size for a completely monolithic version including logic is 5000 mil/SUP 2/.