Pipelined a/d converter

Abstract

Multiple stages sequentially convert respective input analog signals to partial digital data. Each stage includes: a partial A/D converter; a partial D/A converter; an adder that adds/subtracts the analog signal from the previous stage and an output from the partial D/A converter; and a gain amplifier that amplifies an output of the adder and supplies to the next stage. The pipelined A/D converter further includes: a correction value adding unit that adds a correction value to the output from the decoder unit; a correction value calculating unit that, based on the output from the correction value adding unit, calculates an error between the median of the output data and an ideal median at two points in the stage input/output characteristics, saves the calculated value as the correction value and supplies it to the correction value adding unit; and a control unit that controls the above units so as to perform the correction operation. Thereby, aliasing at decoding of the stage output is prevented, enabling an output range to be used effectively.