Circuit for continuous motional series resonant frequency and motional resistance monitoring of quartz crystal resonators by parallel capacitance compensation

Authors: A. Arnau, T. Sogorb, Y. Jiménez

Event: Acusticum, Sevilla, Spain (2002)


A deep analysis of the problem associated to interface circuits for quartz-crystal-microbalance sensors reveals that the so-called static capacitance of the sensor is one of the elements which make the use of oscillators more critical for sensor applications. A phase-locked-loop based circuit designed for compensating the parallel capacitance in quartz crystal resonator sensors is presented. This circuit permits the calibration of the external circuitry to the sensor and provides a continuous measurement of the motional series resonant frequency and motional resistance. An extension and automation of the proposed system for multiple sensor characterization is introduced. Experimental results are also shown.