ANALOG/DIGITAL CONVERTER AND METHOD FOR CONVERTING ANALOG SIGNALS TO DIGITAL SIGNALS

摘要

The objective of the invention is to provide an A/D converter that exhibits fewer malfunctions due to variations in manufacturing. An A/D converter (1) of the invention, which is a cyclic type of analog/digital converter for converting an analog input signal to a digital signal having a predetermined resolution, comprises: a digital approximation unit (10) that includes a comparing unit (13) for comparing the magnitude of an input first analog signal with a threshold value to output a digital value indicating a result of the comparison and that also includes an MDAC unit (14) for amplifying the first analog signal to beta-fold, where beta is greater than one but smaller than two, and for executing a predetermined computation in accordance with the result of the comparison of the comparing unit to output a second analog signal; a multiplexer (20) that, if the MSB is to be computed, outputs the analog input signal and, otherwise, outputs the second analog signal as the first analog signal; a beta estimating unit (30) that estimates the value of beta; and a digital signal outputting unit (40) that sequentially takes in digital values outputted by the comparing unit and that outputs the taken-in digital values as the digital signal.