| 摘要 |
PROBLEM TO BE SOLVED: To provide a resistance measuring device with less influence of a noise. SOLUTION: A voltage injection part 41 generates an AC signal Vx for inspection synchronized with a reference signal Sr. A current measuring part 42 is equipped with a first amplification part 61 having a first operational amplifier wherein one end of a second winding 23 is connected to an inverting input terminal, for converting a current I1 in the second winding 23 into a first voltage signal Vb1; a second amplification part 64 having a second operational amplifier wherein the other end of the second winding 23 is connected to an inverting input terminal, for converting the current I1 into a second voltage signal Vc2 having a reverse phase to the first voltage signal Vb1; a first switching part 63 for detecting each signal Vb2, Vc2 synchronously with a reference signal Sr, and extracting a positive polarity signal Vd; a second switching part 66 for extracting a negative polarity signal Ve similarly; and a third amplification part 67 for outputting a differential signal Vf between each signal Vd, Ve. A processing part 43 calculates a resistance value Rx of a measuring object circuit 5 by calculating a current effective value based on a voltage effective value of the AC signal Vx for inspection and the differential signal Vf. COPYRIGHT: (C)2010,JPO&INPIT |
