| 摘要 |
PURPOSE:To omit a voltmeter of high accuracy, etc. and also to simplify the operation of an operator for correction, by attaining the automatic correction of the offset and the gain with a simple correction means. CONSTITUTION:A control circuit 11 sets an RST signal and a CAL signal at H with a start signal and sets an O/G signal at L. A switch 8 is connected to the (b) side by the O/G signal, and an amplifier 2 is connected to a 0V line. When the output of a D/A converter 1 delivered through the amplifier 2 is set at 0V, the circuit 11 sets the O/G signal at H. While a counter 6 holds then the integration value of the clocks given from a clock generating circuit 10, and the offset control is over. At the same time, the procedure proceeds to the next gain control mode. The switch 8 is connected to the (a) side, and the O/G signal is set at H. Then the reference voltage Vref is supplied to the amplifier 2. When the output delivered via the amplifier 2 exceeds 0V, the circuit 11 sets the CAL signal at L. At the same time, a counter 5 holds the integration value of clocks at that time point.
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