Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a piezoelectric plate having front and back surfaces and an interdigital transducer (IDT). The IDT has a first pitch/mark zone with interleaved fingers having a pitch equal to a first pitch value P.sub.1 and a mark equal to a first mark value M.sub.1, and a second pitch/mark zone with interleaved fingers having a pitch equal to a second pitch value P.sub.2 and a mark equal to a second mark value M.sub.2. A radio frequency signal applied to the IDT causes excitation of a same shear primary acoustic mode by both the first pitch/mark zone and the second pitch/mark zone. P1, M1, P2, and M2, are selected such that an amplitude of spurious modes is reduced as compared to a device having a same primary acoustic mode and a single pitch/mark zone.

Aspects of the disclosure relate to devices, wireless communication apparatuses, methods, and circuitry implementing a SAW resonator with a resonance frequency located at the upper stopband edge. One aspect is an apparatus including an electrode structure with an interdigital transducer (IDT) having a center IDT region, a first IDT region, and a second IDT region. The center IDT region has a first pitch level, and the center IDT region has a first pitch level, and, reflectors comprising a first reflector region and a second reflector region, the first reflector region and the second reflector region each comprise a third pitch level lower than the first pitch level and the second pitch level.

An acoustic wave filter includes a longitudinally coupled resonator including IDT electrodes and a reflector. A standard deviation of a pitch deviation rate of at least one of the reflector and the IDT electrodes is greater than or equal to about 1.4%.

A resonator includes: interdigital transducer (IDT) including first electrode including first base on piezoelectric substrate and extended in reference direction, and first protrusions connected to the first base and extended in direction intersecting with the reference direction, and second electrode including second base on the piezoelectric substrate and extended in the reference direction, and second protrusions connected to the second base and extended in direction intersecting with the reference direction, each of the second protrusions extended to have one of the first protrusions inserted between the second protrusion and another second protrusion adjacent to the second protrusion, wherein a width of each of first specific protrusions included between one end of the IDT and first position at first distance from the one end, among the first protrusions and the second protrusions, decreases from first specific protrusion closest to the first position toward first specific protrusion closest to the one end.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode that is positioned over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a first set of reflectors that is positioned over the piezoelectric layer. The first set of reflectors includes a first number of reflectors having a second pitch. The first pitch is greater than the second pitch. The surface acoustic wave resonator can also include a second set of reflectors that is positioned over the piezoelectric layer. The second set of reflectors includes a second number of reflectors having a third pitch. The second number of reflectors is different from the first number of reflectors.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a set of reflectors that is positioned over the piezoelectric layer. The set of reflectors includes a number of reflectors having a second pitch. The first pitch is greater than the second pitch. The number of reflectors is configured so as to compensate for degradation of a quality factor of the surface acoustic wave resonator due to having the first pitch greater than the second pitch.

Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.

Acoustic resonator devices and filters are disclosed. An acoustic resonator includes a substrate having a surface and a single-crystal piezoelectric plate having parallel front and back surfaces, the back surface attached to the surface of the substrate. An interdigital transducer (IDT) is formed on the front surface of the single-crystal piezoelectric plate. The IDT is configured to excite a primary acoustic mode in the diaphragm in response to a radio frequency signal applied to the IDT. A pitch between adjacent fingers of the IDT is varied along one or both of an aperture of the IDT and a length of the IDT.

An acoustic wave filter includes a piezoelectric substrate, first and second input-output terminals, and a longitudinally coupled resonator unit in a path connecting the first and second input-output terminals to each other, and the resonator unit includes five or more interdigital transducer electrodes aligned in an acoustic wave propagation direction, the IDT electrodes include a center IDT electrode at the center in the propagation direction and first and second IDT electrodes at symmetric or substantially symmetric positions in the propagation direction with respect to the center IDT electrode, each of the first and second IDT electrodes includes a main pitch portion and a pair of narrow-pitch portions provided between the main pitch portion and both ends of the IDT electrode in the propagation direction, and the first and second IDT electrodes differ from each other in the number of electrode fingers of the main pitch portion.

A filter device includes a first filter connected between a common terminal and a first individual terminal, and a second filter connected between the common terminal and a second individual terminal. A pass band of the second filter is in a frequency range lower than a pass band of the first filter. The first filter includes SAW resonators, at least one of which includes divided resonators connected in parallel with each other. Each of the divided resonators includes an IDT. A pitch of the IDT of one of the divided resonators is different from that of another of the divided resonators.