US Patent 8022855 Analog/digital converter

An A/D converter includes a plurality of comparators that performs sampling of a plurality of reference voltages and analog input signals during a sampling time, and compares each of the plurality of reference voltages with each of the plurality of analog signals during a comparison time. The A/D converter detects bubbles in thermometer codes obtained from output signals of the plurality of comparators and adjusts a ratio of the sampling time and the comparison time of the plurality of comparators so as to reduce the bubbles.