Autocalibration of an A/D converter within a CMOS type image sensor

摘要

A method for initializing a counter within a corresponding set (N being an integer greater than 1) of A/D converter of N A/D converters of a single chip CMOS type image sensor in order to minimize non-uniformity across the N A/D converters is provided. The single chip CMOS type image sensor includes an image sensing array having N columns of output line for outputting N analog signals respectively; and a signal process device for generating N digital signal each of which corresponds to one of the N analog signals respectively. The signal process device has N input lines and N A/D converter each of which includes a respective counter for generating one of the N digital signals. The method comprises the steps of applying a predetermined reference voltage at each of the N input lines of the signal process device such that a compensation value corresponding to each set of the A/D converter is obtained. The method further loads the counter of each corresponding set of the A/D converter with the compensation value corresponding to each set of the A/D converter prior to generating the N digital signals. <IMAGE>