| 摘要 |
PURPOSE:To attain digital conversion with high resolution to an analog input signal with a wide voltage range by applying a voltage signal to a summing amplifier with a high gain, comparing signals sequentially with a rough resolution, applying digital conversion, inputting the result again to the summing amplifier at a low gain, comparing sequentially the result with a high resolution and applying digital conversion. CONSTITUTION:An output of a sample and hold circuit 5 to which an output of a digital-analog converter 2 is given via a switch 6 is given to an inverting input of a summing amplifier 7 of the post-stage via a resistor RO. An output of the digital-analog converter 2 is given to the inverting input of the summing amplifier 7 via a switch 8 and a resistor R1. A feedback resistor R2 is connected between the output of the summing amplifier and the inverting input and an output er' is fed to one input of a comparator 3. Sequential comparison analog- digital conversion is applied with a rough resolution in the first period A and the other sequential comparison digital conversion is applied in a period B in a form to be added to the former conversion.
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