| 摘要 |
PROBLEM TO BE SOLVED: To provide a resistance component current detecting circuit of low cost price and superior accuracy, that will not require zero adjustment for a differential amplifier and measure against drift. SOLUTION: A non-inverting amplifying circuit 11 outputs the waveform of the same phase as with an input signal, and an inverting amplifier 12 inverts the phase of the input signal by 180 degrees to output. An integration circuit 14, which is constituted of a differential amplifier and a capacitor, integrates the signal waveform from a changeover connecting means 13. A comparison circuit 15 compares the output of the integration circuit 14 to output a voltage signal H and when the output is higher than a threshold or a voltage signal L, and when the output is lower. An arithmetic control circuit 16 switches the changeover connecting means 13 by the output of a synchronous signal generating means, and therewith computes, to output a current value or a resistance value from the output from the comparison circuit 15. The changeover connecting means 13, that consists of an analog switch, switches a connection for the output terminal A of the integration circuit 14, the output terminal B of the non-inverting circuit 11, the output terminal C of the inverting amplifier circuit 12, or the connection terminal D of a discharge resistance R4 to the input terminal of the integration circuit 14.
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