This paper presents the findings of a design, modeling, and fabrication study of ZnO and PbZr 0 3 Ti 0 7 O 3 thin-film bulk acoustic resonators and filters. Measurements of the high-frequency responses of ZnO resonators having different area are used to develop an acoustic model that accurately represents resonator impedance data. The models are also used to interpret-parameter measurements on thin-film PbZr 0 3 Ti 0 7 O 3-based resonators and a value for the effective coupling coefficient deduced. ZnO and PbZr 0 3 Ti 0 7 O 3 ladder filters were designed based on measured impedance data from single resonators. Ladder filters based on PbZr 0 3 Ti 0 7 O 3 have been fabricated for the first time. It is shown that the high coupling coefficient in PbZr 0 3 Ti 0 7 O 3 leads to bandwidths in the range 100 120 MHz at a center frequency of 1.6 GHz, larger than the bandwidths of ZnO-based filters.

Thin Film Bulk Acoustic Wave Resonators (FBAR) using Lead Zirconate Titanate (PZT) thin films as the piezoelectric active layer will be favourable for voltage controlled oscillators and wide band filter due to the large electro-mechanical coupling coefficient of PZT. This paper reports the fabrication process and results of PZT FBARs and filters. The temperature coefficient and bias voltage effect are also presented.

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Garnet fme particles are prepared by coprecipitation. The saturation magnetization of the particles increases as the annealing temperature increases. Almost all X-ray diffraction peaks from the particles annealed at 700 "c for l h are assigned to garnet. The prepared particles are classified in order to remove the aggregated large particles which are considered to prevent passing of light. The coercive force lowers to half of the initial value after the classification. Faraday rotation of the particles which are dispersed into methylene iodide is confirmed under a polarization microscope. Faraday rotation of the film coated of the particles are shown as a function of wavelength.