| 摘要 |
<p>PROBLEM TO BE SOLVED: To convert an analog signal into a digital signal with high accuracy in a short conversion time by obtaining each count for a 3rd integration period so as to obtain the digital signal corresponding to a converted voltage. SOLUTION: A 1st reference voltage Vr (with opposite polarity to a converted voltage) inputted by an input terminal 2 is integrated by an integration device 4 via a buffer 3 for a 2nd integration period. A 2nd reference voltage -Vr of the same level as and different from the polarity to a 1st reference voltage Vr used for a 2nd integration period is applied to the input terminal 2 to conduct integration toward an integration start point from a trigger point of time of a counter 9 after zero crossing point for a 3rd integration period. The count for the 3rd integration period obtained in this way is proportional to a conversion error generated for the 2nd integration period, then A/D conversion with high accuracy is conducted by calculating the count for the 2nd integration period and the count for the 3rd integration period.</p> |
