CASCADE A/D CONVERTER

PROBLEM TO BE SOLVED: To prevent an error from occurring due to noise by combining and inputting the variation waveform of the codes of comparators, detecting the variation of the codes of the comparators, and removing noise generated at the variation point of the code according to the detection output. SOLUTION: A combining circuit 61 composes the variation waveform of codes of comparators 8e to 8h. Code variation point vicinity detecting means 50e to 50h detect the variation of a code from the variation waveform of the combining circuit 61. An error-correcting circuit 51 removes the noise generated at the code variation point according to the outputs of the code variation point vicinity detecting means 50e to 50h. Here, comparators 13i and 13j and an AND circuit 14a constitute a window comparator (code variation point vicinity detecting means) 50e. Furthermore, comparators 13k and 13l and AND circuits 15a and 15b constitute a code variation point vicinity detecting means 50f, comparators 13m and 13n and AND circuits 16a and 16b constitute a code variation point vicinity detecting means 50g, and comparators 13o and 13p and an AND circuit 17a constitute a code variation point periphery detecting means 50h.