| 摘要 |
PURPOSE:To obtain an analog/digital converter with high accuracy and high resolution by providing a sample holding circuit sampling and holding an output of an integration device and an A/D converter converting the output of the sample holding circuit into a digital signal. CONSTITUTION:An output of the integration device IG is subjected to sample and hold by a sample holding circuit SH, and the sampling period is selected to be an integral number of multiple of a square wave clock + or -EC. Since the output of the integration device IG is increased/decreased between the sampling period 2T, the difference between the sample holding value at a sampling point t1 and the sample holding value at a sampling point t2 is a remainder of the sum of total currents inputted to the integration device IG from zero during the period of t1-t2. The difference is a digital value being the result of two conversions at times t1 and t2 in the analog/ digital conversion circuit A/D. The 2nd digital value is added to the 1st digital value outputted from the count er COU with weight, and the total value is extracted by converting the converted analog input into the digital signal.
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