Impedance detection circuit, impedance detection device, and impedance detection method

摘要

PROBLEM TO BE SOLVED: To provide an impedance detection circuit, an impedance detection device, and an impedance detection method useful for detecting minute impedance or change of minute impedance accurately.;SOLUTION: A first operational amplifier 11 in a core part 1 short-circuits an inversion input terminal and an output terminal. A signal conductor 19 is connected with a non-inversion input terminal. A capacity sensor 18 is connected with the signal conductor 19. A second operational amplifier 12 grounds a non- inversion input terminal. Respective one ends of a first resistance 15 and a second resistance 16 are connected with the inversion input terminal. The other end of the first resistance 15 is connected with an AC voltage generator 14. The other end of the second resistance 16 is connected with the output terminal of the first operational amplifier 11. A signal output terminal 21 of the core part 1 is connected with an inversion amplification part 2. An AC output terminal 22 of the core part 1 and an inversion output terminal 42 of the inversion amplification part 2 are connected with an addition part 3. Non-inversion input terminals of operational amplifiers 36, 40 are grounded.;COPYRIGHT: (C)2001,JPO