| 摘要 |
PROBLEM TO BE SOLVED: To reduce the total offset error as much as possible, by installing an average equalization coupler stage having the reference polarity controlled by a reversing device, regardless of the switching condition of a signal path. SOLUTION: A reversing device 310 is positioned between a sensor system 100 and an input amplifier 220. A sensor signal u1 is reversed or non-reversed by the reversing device 310, to be supplied to an input amplifier 220 as a difference signal u2. An output signal u3' of an impedance transformer stage 230 is supplied to a reversing device 320, and an output signal u4 of the same is supplied to an equalization coupler stage 240. The output of the equalization coupler stage 240 is connected with a voltage divider, and the center tap voltage thereof is supplied to an adjusting circuit 640 for holding an operating point of an output signal u5 at a voltage value ur2. The adjusting circuit 640 drives a current sources 650, 655, the adjusted current is superposed to the output current of the equalization coupler stage 240, and the average of the output signal u5 is used as the desired operating point voltage value ur2. |
