Patent ID: 8154434

Claim:
A pipelined A/D converter configured to: generate, from input analog signals, partial digital data corresponding to a part of bits, where the partial digital data is generated sequentially by cascaded multiple pipeline stages; adjust a timing delay through a pipeline procedure for the partial digital data obtained from the respective pipeline stages; and subsequently add the data together by use of a decoder unit so as to output digital data, each of the pipeline stages comprises: a low-bit-rate partial A/D converter that quantizes either the input analog signal or an output analog signal outputted from the previous pipeline stage and generates the partial digital data; a low-bit-rate partial D/A converter that converts the partial digital data outputted by the partial A/D converter into a reference analog signal; an adder that performs addition/subtraction of the reference analog signal outputted by the partial D/A converter, with respect to the output analog signal; and a gain amplifier that amplifies an output signal from the adder and supplies the signal as the output analog signal to the next pipeline stage, wherein the pipelined A/D converter further comprises: a correction value adding unit that is supplied with the digital data outputted by the decoder unit as a first input and a correction value as a second input, and adds the first input and the second input so as to provide output data; a correction value calculating unit that calculates a median between the output data at two arbitrary points in input/output characteristics of the pipeline stage by using the output of the correction value adding unit as an input, calculates an error between the calculated median and an ideal median, saving the error as the correction value, and outputs the correction value to the correction value adding unit; and a control unit that sets a correction period other than the normal operation period and controls during the correction period the pipeline stage and the correction value calculating unit so as to perform a correction operation of calculating the error.