Analog-to-digital conversion using comparator coupled capacitor digital- to-analog converters

摘要

An analog-to-digital converter circuit (ADC) is described which comprises capacitor based digital-to-analog converter circuits (CDACs) coupled to the inputs of a voltage comparator wherein a reference voltage of one CDAC section has been scaled with respect to a reference voltage of another CDAC section such that one CDAC section adds additional resolution to the other CDAC section. The invention may be applied to single input ADCs as well as to differential ADCs with either type operating in either unipolar or bipolar mode. Also described are various known approaches to both single input and differential CDAC-based successive approximation ADCs, as well as a novel technique of capacitive input voltage attenuation for differential ADCs.