Papers by Keyword: Piezoelectric Resonator

Abstract: The piezoelectric field and structure field of piezoelectric resonator of ultrasonic motor are intercoupling. It is difficult to obtain the solution under some circumstances because of the complex stress boundary condition and the influence of coupling effect. An electro-mechanical coupling finite-element dynamic equation is established on the basis of the Hamilton’s Principle about piezoceramic and elastomer. The equation is decoupled through the shock excitation of the piezoelectric resonator and the piezoelectricity element and material provided by finite-element analysis. As a result, an admittance curve as well as the distribution status of the nodal DOF is obtained, which provides an effective method to solve electro-mechanical coupling problems.

Abstract: An ice detection system consisting of a resonant piezoelectric sensing-element and closed-loop circuit has been developed to automatically and distinctly sense ice films up to 1.3 mm thick. Accretion of ice and/or water on the sensor surface modifies the effective mass and/or stiffness of the vibrating transducer; these variations are sensed by measuring the changes in transducer resonant frequency. In case of ice films, resonant frequency of the transducer increases steadily from 60.9 kHz with no ice to 131.5 kHz when the ice film is 1.3mm thick. The time and temperature stability experiments revealed frequency variety no more than 1 kHz. The resolution of this sensor is better than 0.06mm.

Abstract: Film Bulk Acoustic Wave Resonators (FBAR) at 2.6GHz using AlN piezoelectric material have been fabricated and characterized in this work. A stack of Al bottom electrode, AlN layer and top Al electrode is used to excite the thickness extensional (TE) vibration mode. The FBAR resonator has a quality factor of about 400 and the piezoelectric coupling coefficient of 4.25%, which is critical for RF filter implementation. Moreover, FBAR resonator has been designed to suppress spurious modes in order to ensure higher quality factor. Different filter topologies of ladder/lattice architecture are then explored for effective implementation using several FBAR resonators to build band-pass RF filters.