| 摘要 |
PROBLEM TO BE SOLVED: To provide an analog-to-digital conversion circuit capable of detecting step difference errors of input/output characteristics. SOLUTION: In the analog-to-digital conversion circuit 1, an analog input signal Vin is compared with reference voltage Vrefa by a comparator in a sub A/D converter 9a in a circuit 3 at the first step and an operational amplifier 14 operates in response to an output signal of the comparator. When the reference voltage Vrefa is inputted to the sub A/D converter 9a by switches SW31, SW32, the operational amplifier 14 operates in response to an external input signal generated by a step difference error detection circuit. Difference between a digital output value obtained at the time of response to an external input signal CDSa"1" and a digital output value obtained at the time of response to an external input signal CDSa"0" is equivalent to the size of the step difference error of the input/output characteristics caused by the gain error of the operational amplifier 14. COPYRIGHT: (C)2005,JPO&NCIPI
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