In a SAW element, a piezoelectric layer is laid over a support substrate. An IDT electrode includes a main region and two end regions on two sides of the main region. The end region continues from a portion where electrode finger design is modified up to the end part. A resonance frequency determined by electrode finger design of reflector electrode fingers is lower than a resonance frequency determined by electrode finger design of electrode fingers in the main region. An interval between centers of the electrode fingers in the main region is defined as “a”. Number of electrode fingers configuring the end region is defined as “m”. A distance between a center of an electrode finger among the electrode fingers in the main region which is located on a side closest to the end region and a center of a reflector electrode finger among the reflector electrode fingers which is located on a side closest to the end region is defined as “x”. At this time, the following relationship is satisfied:

0.5×a×(m+1)<x<a×(m+1)

Aspects of this disclosure relate to a surface acoustic wave device with a vertical stack over a piezoelectric layer. The vertical stack can include a first acoustic reflector disposed on the piezoelectric layer, a second acoustic reflector disposed on the piezoelectric layer, and an interdigital transducer electrode disposed on the piezoelectric layer and positioned between the first acoustic reflector and the second acoustic reflector. The interdigital transducer electrode has a first side that is closer to the first acoustic reflector and a second side that is closer to the second acoustic reflector. A vertical arrangement of the vertical stack can be configured such that an acoustic wave propagation velocity of a first region between the first side and a first reflector is faster than an acoustic wave propagation velocity of a second region between the first side and the second side.

Aspects of this disclosure relate to a surface acoustic wave filter with an acoustic velocity adjustment structure. The surface acoustic wave filter can include a first interdigital transducer electrode disposed on a piezoelectric layer, an acoustic reflector disposed on the piezoelectric layer, and a second interdigital transducer electrode disposed on the piezoelectric layer. The second interdigital transducer electrode is longitudinally coupled to the first interdigital transducer electrode and positioned between the first interdigital transducer electrode and the acoustic reflector. The acoustic velocity adjustment structure can be positioned over at least a gap between the first interdigital transducer electrode and the second interdigital transducer electrode. The acoustic velocity adjustment structure can be arranged to increase an acoustic wave propagation velocity in a first region that includes the gap relative to a second region over at least a portion of the first interdigital transducer electrode.

Aspects of this disclosure relate to a surface acoustic wave device that includes a first reflector over a piezoelectric layer, a second reflector over the piezoelectric layer, and an interdigital transducer electrode structure over the piezoelectric layer and positioned between the first reflector and the second reflector. The surface acoustic wave device includes a velocity adjustment layer arranged to adjust acoustic velocity in a region of the surface acoustic wave device. The velocity adjustment layer can be a high speed layer or a low speed layer.

A surface acoustic wave device includes a substrate, a first electrode and a second electrode formed on the substrate to extend along a first direction, wherein the first electrode and the second electrode are alternately disposed along the second direction, one end of the first electrode on one side of the first direction is aligned along the second direction, and one end of the second electrode on the other side of the first direction is aligned along the second direction, a temperature compensation film which covers the first electrode and the second electrode, a first additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the first electrode on the one side of the first direction, and a second additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the second electrode.

A surface acoustic wave (SAW) resonator comprises a plurality of interdigital transducer (IDT) electrodes disposed on a multilayer piezoelectric substrate including a layer of piezoelectric material having a lower surface bonded to an upper surface of a layer of a dielectric material. The dielectric material has a lower surface bonded to an upper surface of a carrier substrate. The plurality of IDT electrodes include an upper layer and a lower layer. The upper layer is formed of a material having a higher conductivity than the lower layer. The lower layer is formed of a material having a higher density than the upper layer to provide for reduction in size of the SAW resonator.

A piezoelectric thin film (PTF) is located above a carrier substrate. The PTF may be Z-cut LiNbO.sub.3 thin film adapted to propagate an acoustic wave in at least one of a first mode excited by an electric field oriented in a longitudinal direction along a length of the PTF or a second mode excited by the electric field oriented at least partially in a thickness direction of the PTF. A first interdigitated transducer (IDT) is disposed on a first end of the PTF. The first IDT is to convert a first electromagnetic signal, traveling in the longitudinal direction, into the acoustic wave. A second IDT is disposed on a second end of the PTF with a gap between the second IDT and the first IDT. The second IDT is to convert the acoustic wave into a second electromagnetic signal, and the gap determines a time delay of the acoustic wave.

A piezoelectric thin film (PTF) is located above a carrier substrate. The PTF can be an aluminum nitride thin film adapted to propagate an acoustic wave in at least one of a first mode excited by an electric field oriented at least partially in a longitudinal direction along a length of the PTF or a second mode excited by the electric field oriented in a thickness direction of the PTF. A first interdigitated transducer (IDT) is disposed on a first end of the PTF and converts a first electromagnetic signal, traveling in the longitudinal direction, into the acoustic wave. A second IDT is disposed on a second end of the PTF with a gap between the second IDT and the first IDT. The second IDT is to convert the acoustic wave into a second electromagnetic signal, and the gap determines a time delay of the acoustic wave.

A piezoelectric thin film (PTF) is located above a carrier substrate. The PTF may be X-cut LiNbO.sub.3 thin film adapted to propagate an acoustic wave in at least one of a first mode excited by an electric field oriented in a longitudinal direction along a length of the PTF or a second mode excited by the electric field oriented at least partially in a thickness direction of the PTF. A first interdigitated transducer (IDT) is disposed on a first end of the PTF. The first IDT is to convert a first electromagnetic signal, traveling in the longitudinal direction, into the acoustic wave. A second IDT is disposed on a second end of the PTF with a gap between the second IDT and the first IDT. The second IDT is to convert the acoustic wave into a second electromagnetic signal.

A surface acoustic wave resonator comprises interdigital transducer (IDT) electrodes disposed on an upper surface of a piezoelectric substrate between first and second reflector gratings each including reflector electrodes. The IDT electrodes include a central region having a first width in a direction perpendicular to an extension direction of the IDT electrodes and edge regions each having a second width on opposite sides of the central region. The IDT electrodes have a lesser average pitch in the central region than an average pitch of the IDT electrodes in each of the edge regions. The reflector electrodes have a lesser average pitch than the average pitch of the IDT electrodes in the central region.