This paper presents a readout circuit for wireless passive LC sensors, where the phase of the readout coil shows a small "dip" nearby the sensor's resonant frequency in the low-coupling-coefficient condition (a distance between the readout coil and the LC tank longer than 100 mm). To address this issue and enhance device sensitivity, in this study, a new symmetrical differential drive circuit was proposed where theoretical analysis and experimental verification were performed. The symmetrical differential drive circuit amplified the phase-dip at least 6 times when the scale factor between the reference inductor and the readout coil was 1.138. The proposed readout circuit was used to detect the variations of pressure with a 12 mm×12 mm×14 mm LC pressure sensor at an operational distance up to 100 mm between the LC sensor and the readout circuit, recording a measurement resolution lower than 0.4 kPa.
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机译：本文介绍了一种用于无线无源LC传感器的读出电路，其中在低耦合系数条件下，读出线圈的相位在传感器的谐振频率附近显示一个小的“倾角”（读出线圈与LC储能罐之间的距离较长）大于100毫米）。为了解决这个问题并提高器件的灵敏度，在这项研究中，提出了一种新的对称差分驱动电路，其中进行了理论分析和实验验证。当参考电感器和读出线圈之间的比例因子为1.138时，对称差分驱动电路将相差放大至少6倍。拟议的读出电路用于通过12 mm×12 mm×14 mm LC压力传感器检测压力变化，在LC传感器和读出电路之间的最大工作距离为100 mm，记录的测量分辨率低于0.4 kPa 。
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