A Compact Planar Inductive Angular Sensor With Small Latency and Low Power Consumption

This article proposes a contactless planar inductive sensor for angular displacement measurement with low cost, power consumption, and latency. The novel sensor comprises multiple receiving coils (RXs) sharing the same excitation coil and rotor. Affected by the eddy current on the rotor, the induced voltages of RXs are in the form of sine with different amplitudes. Considering the fabrication and assembly error, this study selects three independent RXs to remove the third harmonic of sensed signals. The analog front-end circuit is integrated with the front sensor to minimize the volume and cost of the measurement system. As we know, the work achieves an integrated synchronous dual-peak sampling technique for the first time. Combined with an improved digital phase lock loop, the presented strategy significantly reduces the system latency and complexity. The operation principles and implementation of the sensor are all explained in detail. A sensor prototype has been fabricated using the 180-nm CMOS technique for validation. Experimental results have shown that the demodulation accuracy of the proposed inductive sensor is 0.07° in the full range after calibration.