| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a successive approximation AD converter that implements high accuracy by correctively controlling gate capacitances of transistors of four-terminal comparators connected with output terminals of a sub DAC to a desired capacitance ratio. <P>SOLUTION: A successive approximation AD converter includes: main DACs 102, 103 for outputting corresponding voltages in response to a digital value DSR setting a search area; a sub DAC 101 for outputting corresponding voltages in response to control signals setting the search area; four-terminal comparators 105, 107 for comparing the voltages from the main DACs 102, 103 and sub DAC 101; a comparator 106 for comparing the output voltages of main DAC+ (102) and main DAC- (103); a selector 104 for switching between the outputs A1, B1, D1, E1 of the sub DAC 101 or a common voltage VCM on the basis of a switching control signal; and a successive approximation register logic 108 for feeding the switching control signal to the selector 104. <P>COPYRIGHT: (C)2013,JPO&INPIT |
