Centre National De La Recherche Scientifique

Université De Franche Comte

Etat Francais Represente Par Le Delegue General Pour L'armement

Dorian Gachon

Sylvain Ballandras

Emilie Courjon

Roger Petit

The invention relates to a resonator of the harmonic bulk acoustic resonator HBAR type, comprising a piezoelectric transducer () clamped between two electrodes () with a strong electroacoustic coupling, cut according to a first cutting angle &#x398;1, and an acoustic substrate () with a working frequency acoustic quality coefficient at least equal to 5&#xb7;10, cut according to a second cutting angle &#x398;2 with at least one shearing vibration mode. The transducer and the substrate are arranged in such a way that the polarization direction of the shearing mode of the transducer and the polarization direction of the shearing of the substrate are aligned, and the second cutting angle &#x398;2 is such that the temperature coefficient of the frequency of the first order CTFB1 corresponding to the shearing mode and to the second cutting angle &#x398;2 is zero with inversion of the sign thereof on either side of, or equal to, a bias.

HBAR resonator with high temperature stability

The invention relates to a resonator of the high bulk acoustic resonator HBAR type, for operating at a pre-determined working frequency, comprising: a piezoelectric transducer (), an acoustic substrate (), a counter-electrode () formed by a metal layer adhering to a first face of the transducer () and a face of the acoustic substrate (), and an electrode () arranged on a second face of the transducer () facing away from the first face of the transducer () and the substrate (). Said resonator is characterized in that the relative arrangement of the transducer () and the substrate () is such that the polarization direction P of the shearing mode of the transducer () and the direction of polarization P of the at least one shearing mode of the substrate () corresponding to the second cutting angle &#x3b8;are aligned, and the second cutting angle &#x3b8;of the substrate () is such that the temperature coefficient of the frequency of the corresponding first order CTFBis a local extremum with an absolute value of less than 20 ppm&#xb7;K, and the variation of CTFBfrom said value of &#x398;is slight with an absolute value of less than 2 ppm&#xb7;K/degree.

HBAR resonator with a high level of integration

The elementary filter of the HBAR type includes two resonators () of the HBAR type which are each formed by a transducer () and a substrate () which are coupled in a suitable manner by electroacoustic waves. The first resonator (), the second resonator () and the coupling element () by way of evanescent waves include the same monobloc acoustic substrate () which is arranged facing and coupled to the piezoelectric transducer () by waves having the same longitudinal or transverse vibration mode through the same reference electrode ().

Cross-coupling filter elements in resonant structures with bulk waves having multiple harmonic resonances

The present invention relates to the field of acoustic wave devices, and particularly to that of transducers capable of operating at very high frequencies, from a few hundred MHz to several gigahertz, and its subject is more particularly an interface acoustic wave device including at least two substrates and a layer of ferroelectric material, the latter being contained between a first electrode and a second electrode and having first positive-polarization domains and second negative-polarization domains, the first and second domains being alternated, wherein the assembly constituted by the first electrode, the layer of ferroelectric material, and the second electrode is contained between a first substrate and a second substrate.

Growing community of inventors

Besancon, France

Dorian Gachon