| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a processing circuit of an electrostatic capacitance sensor, which is reduced in noise.SOLUTION: In a sensor circuit configuration, capacitance of a sensor capacitor 1 is measured by a circuit 8 which supplies a corresponding sensor signal V. The circuit 8 comprises; a differential amplifier 2 including an input, an output and a feedback loop between the input and the output. The circuit 8 further comprises a first capacitor 3 arranged in the feedback loop, and a switching device for charging the sensor capacitor 1 from a voltage source 5 in a first phaseΦ1 and for transferring a charge from the sensor capacitor 1 to the first capacitor 3 in a second phaseΦ2. The circuit 8 further comprises a second capacitor 6 arranged in parallel to the first capacitor 3 in the second phaseΦ2, for limiting a gain of noise generated by the differential amplifier 2. The sensor circuit configuration further includes a low pass filter for filtering the sensor signal V.</p> |
