A New Readout Method for a High Sensitivity Capacitance Sensor Based on the Weakly Coupled Resonators

Abstract

This paper proposes a new readout method for a sensor to detect minute variations in the capacitance. A sensor is based on the weakly coupled electrical resonators that use an amplitude ratio (AR) as an output signal. A new readout scheme with a relatively higher output sensitivity is proposed to measure the relative changes in the input capacitor. A mathematical model is derived to express the readout output as a function of change in the capacitance. To validate the theoretical model, a system is modelled and designed using an industry-standard electronic circuit design environment. SPICE simulation results are presented for a wide range of design parameters, such as varying coupling factors between the two electrical resonators. Sensitivity comparison between the existing and the proposed AR readout is presented to show the effectiveness of the method of detection proposed in this work.