科研之友
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摘要
In this brief, a high sensitivity measuring system for capacitive sensor to detect moving target is presented. It mainly consists of a capacitance measuring circuit and a dc-blocking circuit. The capacitance measuring circuit is used to convert a capacitance to a dc voltage and the dc-blocking circuit is employed to extract the voltage variation. The experimental results show that when the measured capacitor is between 1 pF to 7.5 pF, the sensitivity is 3.53 V/pF, the linearity error is 6.13%, the SNR increases from 26.6 dB to 57.7 dB, the resolution is 3.1 fF and the time delay is about 4 mu s. Comparing to five other common capacitance measuring circuits, the proposed one offers plain design, high sensitivity, and fast speed. Simulation results show that the proposed dc-blocking circuit has short time delay and unattenuated output. Moreover, as demonstrated by system tests, the proposed measuring system is qualified for capacitive sensor for detection of moving target with different speeds.
