Capacitance Detection Based on High Order Synchronization Sensing

Synchronization is a ubiquitous phenomenon first discovered by Christiaan Huygens and has been observed in a variety of systems. However, little work has been done to utilize the synchronization effect for sensing applications. Here, we demonstrate a new concept of exploring synchronization effects for capacitive sensing. This paper presents a novel validation of high sensitivity capacitive readout method based on high order synchronization sensing technique for the first time. A high order synchronization of 11:1 is realized between the micromechanical oscillator and the electrical oscillator, considering the trade-offs of sensitivity, noise floor and synchronization bandwidth. The theoretical analysis is validated by the experimental results. With the harmonic amplitude Vp = 500 mV, the measured sensitivity (404 Hz nF) indicates an improvement of 11 times in comparison with that of the unsynchronized capacitance detection method. In addition, the frequency stability and noise floor of the unsynchronized RLC circuit are 400 ppm and 18.5 fF Hz @0.021 Hz, and reduced to 10 ppm (1.01 pF) and 0.13 fF Hz (1.37ppb) @0.013 Hz when the bi-domain coupled synchronization is active. The proposed capacitive readout method opens up the new possibilities for more advanced integrated solutions relying on synchronization for readout circuits of capacitive seismic sensors.