Patent ID: 8810106

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 θ 1 defined by the nomenclature (YX 1 )/θ of the IEEE Std-176 (1949 revision) standard, such that the electroacoustic coupling of the shear waves within that material alone is greater than 5%, the transducer ( 6 ) having a temperature coefficient of the frequency CTFA as a function of the first cutting angle θ 1 , an acoustic substrate ( 10 ) formed by a second layer with a second thickness of a second material having a working 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 θ 2 defined by the nomenclature (YX 1 )/θ of the IEEE Std-176 (1949 revision) standard, having at least one polarization direction {right arrow over (P)} B1 corresponding to a first shearing mode of vibration, the acoustic substrate ( 10 ) having a temperature coefficient of the frequency of the first order CTFB 1 corresponding to the at least one shearing mode and depending on the second cutting angle θ 2 , 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 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 ) 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 θ 2 are aligned, and the second cutting angle θ 2 of the substrate ( 10 ) is such that the temperature coefficient of the frequency of the corresponding first order CTFB 1 is a local extremum with an absolute value of less than 20 ppm·K −1 and the variation of CTFB 1 around that value of θ 2 is slight with an absolute value of less than 2 ppm·K −1 /degree.