Apparatus and a method for analog to digital conversion using plural reference signals and comparators

Abstract

An analog-to-digital converter is provided. The analog-to-digital converter capable of increasing the processing speed of the converter by using a number of SAR registers. The analog-to-digital converter, includes: a storage circuit for storing a first, a second and a third digital signals, respectively; a controller for controlling conversions of two bits contained in one of the digital signals stored at the storing means in response to a first, a second and a third comparing signals; a circuit, having a first, a second and a third digital-to-analog converters, for converting the first, the second and the third digital signals by using each of the digital-to-analog converters to provide a first, a second and a third analog reference signals; and a comparator for comparing each of the analog reference signals to an analog input signal which is to be converted, to provide said first, said second and said third comparing signals, and having a first, a second and a third comparators each of which performs each of the comparisons.