Electrical measurement of high frequency ceramic resonators

A report is presented on the use of exact infinite-plate linear quasi-static piezoelectric elastic models to interpret electrical measurements on thickness-mode resonators made from PZT materials. These interpretations were used to determine the material constants of the piezoelectric ceramic. A need for completeness required the definition of electrical models of both the resonator and the measurement fixture. The electrical model of the measurement fixture included parasitic series inductances. During frequency measurements of large-area high-frequency resonators, the very low impedance level of the resonator and the fixture parasitics combine to produce resonance-frequency shifts. Algebraic derivation and computer-simulation results show how these resonance-frequency shifts depend on the sample material´s properties and geometry and on the fixture parasitic elements. This resulted in development of a proper model; piezoelectric coupling was determined in the presence of series induction with the model and the measurement of two resonance frequencies