| 摘要 |
A comparator offset correction device opens an open switch 205 and closes a short-circuit switch 204 in offset correction of a comparator 201. In this state, a controller 203 allows the comparator 201 to repeat, more than once, the operation of comparing reference voltages 101 input to two input terminals with each other. The filter 202 outputs a frequency signal obtained by smoothing a plurality of comparison results. Based on the frequency signal from the filter 202, the controller 203 outputs a threshold value control signal to the comparator 201 so that the ratio of a high-level voltage to a low-level voltage in the results of the comparison in the comparator 201 is 50%. Thus, even when a current which will be input may differ from a current which is currently input due to, for example, the influence of noise, the threshold value offset amount is normally corrected.
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