Interdigital transducer (IDT) and reflective structure arrangements for surface acoustic wave (SAW) devices are disclosed. Representative SAW devices are described herein with reduced overall size while maintaining good quality factors. In certain embodiments, a SAW device may include an IDT arranged between reflective structures on a piezoelectric material. The reflective structures may include reflective IDTs that are configured to have a phase difference with the IDT to reflect and confine acoustic waves in the piezoelectric material. In certain embodiments, the reflective structures may be electrically connected to at least one of an input signal or an output signal. In this manner, the reflective structures may be configured with reduced size as compared to conventional reflective structures such as gratings, thereby providing a SAW device with reduced dimensions without a negative impact on device performance.

A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.

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.

Aspects of this disclosure relate to a surface acoustic wave filter with an integrated temperature sensor. The integrated temperature sensor can be a resistive thermal device configured as a reflective grating for a surface acoustic wave resonator, for example. A radio frequency system can provide over temperature protection by reducing a power level of a radio frequency signal provided to the surface acoustic wave filter responsive to an indication of temperature provided by the integrated temperature sensor satisfying a threshold.

Aspects of this disclosure relate to a surface acoustic wave filter with an integrated temperature sensor. The integrated temperature sensor can be a resistive thermal device configured as a reflective grating for a surface acoustic wave resonator, for example. A radio frequency system can provide over temperature protection by reducing a power level of a radio frequency signal provided to the surface acoustic wave filter responsive to an indication of temperature provided by the integrated temperature sensor satisfying a threshold.

An SAW resonator includes a piezoelectric substrate, an IDT electrode, and a pair of reflectors. The IDT electrode includes pluralities of electrode fingers which are aligned on the piezoelectric substrate in a direction of propagation of a SAW. The pair of reflectors are located on the two sides of the pluralities of electrode fingers on the piezoelectric substrate in the direction of propagation. The IDT electrode includes a plurality of areas which includes pluralities of electrode fingers distributed to them and have different resonance frequencies from each other. The plurality of areas include at least three areas. The second highest resonance frequency among all areas is lower than an intermediate value between the lowest resonance frequency among all areas and the highest resonance frequency among all areas.

An acoustic wave device comprises a piezoelectric substrate, interdigital transducer electrodes having an electrode pitch ?.sub.0, and first and second reflector gratings disposed on opposite respective sides of the interdigital transducer electrodes in a propagation direction of a main acoustic wave through the acoustic wave device, the first reflector grating having a reflector electrode pitch ?.sub.1 throughout an entirety of the first reflector grating that is different than a reflector electrode pitch ?.sub.2 throughout an entirety of the second reflector grating to suppress ripples in a conductance curve of the acoustic wave device.

An input port, an output port, and a plurality of serial resonators and a plurality of parallel resonators connected in a ladder type between the input port and the output port and including IDT electrodes are provided. The plurality of parallel resonators include at least one first parallel resonator having a resonance frequency lower than resonance frequencies of the plurality of serial resonators, and at least one second parallel resonator having a resonance frequency higher than antiresonance frequencies of the plurality of serial resonators.

An acoustic wave element of the present invention includes a piezoelectric substrate, an excitation electrode which is arranged on the piezoelectric substrate and includes a plurality of electrode fingers, and two reflectors arranged on the piezoelectric substrate, each of which includes a plurality of reflection electrode fingers, which sandwich the excitation electrode therebetween in the propagation direction of an acoustic wave. The excitation electrode includes a main region in the center vicinity of the line of the plurality of electrode fingers in which the intervals between the centers of the plurality of electrode fingers are uniformly a first interval. In the reflector, at least one of the reflection electrode fingers shifts to the excitation electrode side relative to virtual electrode finger positions which are repeatedly set at the first intervals from the electrode fingers in the main region.