A filter comprising first and second BAW resonators. The first BAW resonator having a piezoelectric layer, located between a top electrode and a bottom electrode, and a dielectric layer located between the bottom electrode and an additional electrode. Wherein the dielectric layer, the bottom electrode and the additional electrode are configured to provide an additional capacitance in the resonator. The second BAW resonator having at least one less electrode than the first BAW resonator.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and slanted acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with slanted pitches.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers arranged to suppress a spurious response due to shear horizontal mode of the multi-mode surface acoustic wave filter. For example, the acoustic reflector fingers can include stepped lengths and/or slanted pitches to suppress the spurious response due to shear horizontal mode.

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and stepped acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with stepped lengths.

A BAW resonator (1) comprises a piezoelectric layer (2) located between a top electrode (4) and a bottom electrode (3) and comprises a dielectric layer (9) located between the bottom electrode (3) and an additional electrode (11), wherein the dielectric layer (9), the bottom electrode (3) and the additional electrode (11) are configured to provide an additional capacitance in the resonator (1). The BAW resonator (1) may be part of a ladder-type resonator arrangement (100).

Multi-mode surface acoustic wave filters are disclosed. A multi-mode surface acoustic wave filter can include a plurality of interdigital transducer electrodes that are longitudinally coupled to each other and stepped acoustic reflectors on opposing sides of the plurality of interdigital transducer electrodes. The acoustic reflectors include acoustic reflector fingers with stepped lengths.

A ladder filter includes series-arm resonators each including an IDT electrode and a reflector, and a parallel-arm resonator. In at least one of the series-arm resonators, where a wavelength that is determined by an electrode finger pitch of the IDT electrode is , an electrode finger center-to-center distance between an electrode finger located closest to the reflector among electrode fingers of the IDT electrode and an electrode finger located closest to the IDT electrode among electrode fingers of the reflector is less than about 0.5, and an anti-resonant frequency of the at least one of the series-arm resonators is higher than an anti-resonant frequency of at least another one of the series-arm resonators.

Surface acoustic wave (SAW) devices and methods of fabricating SAW devices are disclosed. The disclosed SAW device includes a piezoelectric layer. The SAW device also includes at least one transducer coupled to the piezoelectric layer. The transducer includes a first set of electrodes and a second set of electrodes. Each electrode in the first set of electrodes is directly adjacent to at least one electrodes in the second set of electrodes along a wave propagation axis, and the first and second set of electrodes are separated from each other along a depth axis.

Various arrangements for electrically coupling the electrodes of coupled resonator structures (CRSes) to form unique two- and three-terminal devices as well as the use of such CRSes in filter networks are disclosed.

A ladder filter includes a plurality of series-arm resonators and parallel-arm resonators including surface acoustic wave resonators. A metallization ratio of the series-arm resonator having the smallest electrostatic capacity among the plurality of series-arm resonators is the smallest among the plurality of series-arm resonators and an electrode finger pitch of the series-arm resonator having the smallest electrostatic capacity is the largest among electrode finger pitches of the plurality of series-arm resonators.