ANALOG/DIGITAL CONVERTER

PROBLEM TO BE SOLVED: To reduce a consumption current of a sample/hold part, while attempting increase in speed. SOLUTION: The analog/digital converter includes the sample/hold part including first and second sample/hold circuits 11a, 11b inputting first and second signals thereto, respectively, and an amplifier 12 for inputting output signals of the sample/hold circuits thereto; an analog/digital conversion circuit 14, subjecting the output signal of the amplifier to analog/digital conversion, and outputting third and fourth signals corresponding to the first and second signals, in parallel with each other; a first maximum value detecting circuit 23a detecting the maximum value of the amplitude based on the third signal; a second maximum value detecting circuit 23b detecting the maximum value of the amplitude based on the fourth signal; a maximum value determining circuit 24 determining the maximum value of amplitude from among the output results of the first and second maximum value detecting circuits; and a variable current source 13 for controlling the current value of the amplifier, in response to the output result of the maximum value determining circuit. COPYRIGHT: (C)2010,JPO&INPIT