Patent ID: 8829764

Claim:
A resonator of the high bulk acoustic resonator type for operating at a predetermined working frequency, comprising: a piezoelectric transducer ( 6 ) formed by a layer with a first thickness of a first material oriented along an angle φ defined by the nomenclature (YXw)/φ of the IEEE Std-176 (1949 revision) standard equal to zero, cut along a first cutting angle θ1 defined by the nomenclature (YXl)/θ of the IEEE Std-176 (1949 revision) standard, such that the electroacoustic coupling of the shear waves for that material alone is greater than 5%, the transducer having a temperature coefficient of the frequency of the first order CTFA as a function of the first cutting angle θ1, an acoustic substrate ( 10 ) formed by a second layer with a second thickness of a second material having a functional frequency acoustic quality coefficient product at least equal to 5·10 12 , oriented along an angle φ defined by the nomenclature (YXw)/φ of the IEEE Std-176 (1949 revision) standard equal to zero, cut along a second cutting angle θ2 defined by the nomenclature (YXl)/θ of the IEEE Std-176 (1949 revision) standard, having at least one polarization direction {right arrow over (P)} B1 corresponding to a shearing mode of vibration, the acoustic substrate ( 10 ) having a temperature coefficient of the frequency of the first order CTFB1 corresponding to the at least one shearing mode and depending on the second cutting angle θ2, a counter-electrode ( 8 ) formed by a layer of metal adhering to a first face of the transducer ( 6 ) and a face of the acoustic substrate ( 10 ), and an upper electrode ( 4 ) arranged on a second face of the transducer ( 6 ) facing away from the first face of the transducer ( 6 ) and the substrate ( 10 ), characterized in that the relative arrangement of the transducer ( 6 ) and the substrate ( 10 ) is such that the direction of polarization {right arrow over (P)} A of the shearing mode of the transducer ( 6 ) corresponding to the first cutting angle θ1 and the polarization direction {right arrow over (P)} B1 of the at least one shearing mode of the substrate ( 10 ) corresponding to the second cutting angle θ2 are aligned, and the second cutting angle θ2 of the substrate ( 10 ) is such that the temperature coefficient of the frequency of the first order CTFB1 corresponding to the at least one shear mode and to the second cutting angle θ2 is zero with inversion of its sign on either side or equal to the opposite of the temperature coefficient of frequency CTFA of the transducer ( 6 ) weighted by an increasing function of the ratio of the second thickness over the first thickness when the ratio is greater than or equal to 0.02.