| 摘要 |
PROBLEM TO BE SOLVED: To provide an impedance detector circuit which is capable of accurately detecting a very small capacitance and is suited for miniaturization. SOLUTION: A capacitance detector circuit 10 comprises a DC voltage generator 11, an operational amplifier 14 having a non-inverting input terminal connected to a specified potential, an impedance transformer 16, a resistor (R1 ) 12 connected between the DC voltage generator 11 and an inverting input terminal of the operational amplifier 14, a resistor (R2 ) 13 connected between the inverting input terminal of the operational amplifier 14 and an output terminal of the transformer 16, and a capacitor 15 connected between an output terminal of the operational amplifier 14 and an input terminal of the transformer 16. A capacitor 17, under test is connected between the input terminal of the transformer 16 and the specified potential.
|
