一种简单的单频无源LC传感器读取系统设计

Design of a Simple Single Frequency Passive LC Sensor Readout System

为了实现无源LC传感器信号的高灵敏度检测,提出了一种简单、高效的单频无源LC传感器读取系统。该系统通过磁耦合读取线圈和传感器线圈,利用固定电容与电容传感器并联降低谐振频率以便进行测量。首先,通过读取线圈将传感器的电容转换成励磁电压和电流之间的相角(φ)。然后使用相敏检测器获得由tanφ给出的最终输出结果。其中,相敏检测器的输入为电压和与信号成比例的电流。理论分析和实验结果显示,提出系统能够实现传感器变化信号的高灵敏度检测。在±5 pF的范围内测试得到的灵敏度为5.5 (°)/pF且平均误差约为0.38%。

In order to realize the high sensitivity detection of passive LC sensor signal,a simple and efficient single frequency passive LC sensor reading system is proposed.The system uses the magnetic coupling to read the coil and the sensor coil,and uses the fixed capacitance and the capacitance sensor to reduce the resonance frequency in parallel.First,the capacitance of the sensor is converted into the phase angle(Ф)between the excitation voltage and current by reading the coil.The final output results obtained by tanФare then obtained using a phase sensitive detector.The input of the phase sensitive detector is voltage and current proportional to the signal.Theoretical analysis and experimental results show that the proposed system can detect the high sensitivity of the sensor signal.In the range of±5 pF,the sensitivity is 5.5(°)/pF and the average error is about 0.38%.