US Army Res. Lab., AMSRL-PS, Fort Monmouth, NJ 07703-5601
Rutgers Univ., New Brunswick, NJ 08855
Equivalent circuits for characterizing piezoelectric resonators have been used for many years, and in a wide variety of applications. The future will see applications extended through the UHF band for ferroelectric ceramic thin-film resonant microstructures, e.g., for cellular radios. Such applications will require material and processing uniformity far greater than is currently achieved, and means for their verification. Piezoceramics occupy a difficult position, however, when it is required to obtain precise material parameters from broadband electrical measurements. This situation arises because of their particular attributes: high coupling and moderate loss. Highly accurate lumped equivalent networks for these frequencies have been developed for both canonical cases of thickness- and lateral-field excitation. Measurements on these circuits permit the extraction of the complex dielectric, piezoelectric, and elastic parameters of the ceramic material. This paper discusses both traditional and modern electrical network descriptions of piezoelectric resonators; and also treats how they are modified by the conditions of excitation and inclusion of loss mechanisms.