Energy trapping resonators and integrated filters using the AT cut of quartz like materials

The properties of AT resonators made with quartz, berlinite, and GaPO4 are compared using calculations made with a three-dimensional model that takes into account the energy trapping phenomena existing in real resonators. These computations show that the high coupling quartz-like materials lead to very interesting properties in terms of inductance and capacitance ration. The AT resonators using berlinite and GaPO4 achieve much greater filter bandwidth or oscillator shifts than AT quartz. For several applications, e.g., VHF filters with suppression of the antisymmetrical anharmonics, the use of berlinite appears to constitute an interesting compromise. For applications requiring the largest bandwidth or oscillators shifts, the use of gallium phosphate appears to be very promising.<
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