TRANSVERSELY-EXCITED FILM BULK ACOUSTIC RESONATORS WITH THREE-LAYER ELECTRODES

Abstract: a bulk acoustic resonator device and filter device including the same is provided. the resonator includes a substrate; a piezoelectric layer attached to the substrate; and an interdigital transducer having interleaved fingers on the piezoelectric layer. the interleaved fingers include a first layer proximate the piezoelectric layer, a second layer over the first layer, and a third layer over the second layer such that the second layer is between the first and third layers. adjacent layers of the first, second and third layers are comprised of different metals. moreover, a primary shear acoustic mode is excited in the piezoelectric layer and is a bulk shear mode where acoustic energy propagates in a direction predominantly orthogonal to the surface of the piezoelectric layer and predominantly orthogonal to a direction of an electric field created by the interleaved fingers of the idt that is predominantly lateral in the piezoelectric layer.

Inventor(s): Julius KOSKELA, Bryant Garcia

CPC Classification: H03H9/131 (IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (measuring, testing ; arrangements for producing a reverberation or echo sound ; impedance networks or resonators consisting of distributed impedances, e.g. of the waveguide type, ; control of amplification, e.g. bandwidth control of amplifiers, ; tuning resonant circuits, e.g. tuning coupled resonant circuits, ; networks for modifying the frequency characteristics of communication systems ))

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