| 摘要 |
PROBLEM TO BE SOLVED: To eliminate a measuring error caused by noises or the like with a simple structure by providing an amplifying means for amplifying an input signal fetched by first and second switching means. SOLUTION: When the ON resistance of each of switching means S19 to S13 is set to (γ) and a noise voltage applied between the terminal t12 of a voltage source 11 and a ground G via a resistor R is set to V, a noise current is caused to flow to the ground G through an input line and the means S13 and a noise voltage eel is applied to the terminal t12. Without the means S13, the noise current by the voltage V is directly supplied to an amplifying means 2 and consequently, a large error is created. However, since the current is caused to flow through the means S13, because R is sufficiently larger than (γ), an error voltage e01 is extremely small, an error voltage applied to each input terminal of the means 2 is very small so as to allow its influence to be ignored and thus, no error is created. Similarly, for switching means S21 to S23, noise errors are reduced.
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