| 摘要 |
PURPOSE:To attain the highly accurate sampling of an input data by connecting an input of an operational amplifier connected to a sampling capacitance to an output of the operational amplifier via a switch. CONSTITUTION:An analog input high speed sampling section 17 is provided with switches 10-15 switching the connection between a differential amplifier 5 and a differential amplifier circuit from which a desired gain is obtained over the range of a power voltage. The input and output of the operational amplifier 9 are connected by using a clock 2 and one side of a sampling capacitor 8 is fixed to an intermediate level between the circuit highest potential and the lowest potential. Further, a reference voltage source 7 is connected to the sampling capacitor 8 via the switch 14 by using a clock 3 and an analog input voltage and a reference voltage are compared by the operational amplifier 9. Thus, since the analog input voltage is suppressed within a sampling error of 0.67% over the range of power voltage, the high accuracy sampling time is decreased.
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