Mass-loading effect on parameters of quartz and langasite resonators: Recent results

This paper presents some of the more relevant results concerning the mass-l oading influence on quartz resonators and monolithic filter characteristics , and recent experimental results about the mass-loading effect on electric al parameters of langasite resonators. Based on the Ballato's transmission- line analogs of the trapped-energy resonators vibrating in thickness-shear mode, the mass-loading effect on resonator characteristics was studied. The effective mass-loading, motional inductance and quality factor of quartz a nd langasite resonators, as a function of harmonic order for various electr ode parameters, were computed. In the frame of the Tiersten's analysis of m onolithic structure, the theoretical calculations of the coupling coefficie nt of two-pole quartz and langasite monolithic filters as a function of mas s-loading were performed. The analysis of these results shows that the mass -loading influence on characteristics of langasite resonators and monolithi c filters is lower than on those of the quartz devices.