Abstract: An acoustic wave resonator includes: a support substrate; a piezoelectric substrate located on the support substrate; a first amorphous layer that is in contact with the support substrate and is mainly composed of one or more constituent elements of the support substrate; a second amorphous layer that is in contact with the piezoelectric substrate and the first amorphous layer, is mainly composed of one or more constituent elements of the piezoelectric substrate, and is thinner than the first amorphous layer; and a pair of comb-shaped electrodes that is located on an opposite surface of the piezoelectric substrate from the support substrate, each of the pair of comb-shaped electrodes including electrode fingers.

Abstract: An acoustic wave device includes: a piezoelectric substrate; a comb-shaped electrode located on the piezoelectric substrate; a pair of reflectors located on the piezoelectric substrate, the pair of reflectors sandwiching the comb-shaped electrode; a first dielectric film located on the piezoelectric substrate, the first dielectric film covering the pair of reflectors and having side surfaces in regions between the comb-shaped electrode and the pair of reflectors; and a second dielectric film located on the piezoelectric substrate, the second dielectric film covering the comb-shaped electrode and being in contact with the side surfaces of the first dielectric film.

Abstract: A method of fabricating an acoustic wave device includes: forming a piezoelectric thin film resonator and a second lower electrode on a substrate, the piezoelectric thin film resonator having a resonance region in which a first lower electrode and a first upper electrode face each other across a piezoelectric film, the piezoelectric film and the first upper electrode are not formed on the second lower electrode outside the resonance region; forming a first dielectric film in the resonance region and a second dielectric film on the second lower electrode outside the resonance region at a same time, the first dielectric film and the second dielectric film being made of a material different from a material of the piezoelectric film; and forming a second upper electrode on the second dielectric film, the second upper electrode facing the second lower electrode.

Abstract: An acoustic wave resonator includes: a support substrate; a piezoelectric substrate located on the support substrate; a first amorphous layer that is in contact with the support substrate and is mainly composed of one or more constituent elements of the support substrate; a second amorphous layer that is in contact with the piezoelectric substrate and the first amorphous layer, is mainly composed of one or more constituent elements of the piezoelectric substrate, and is thinner than the first amorphous layer; and a pair of comb-shaped electrodes that is located on an opposite surface of the piezoelectric substrate from the support substrate, each of the pair of comb-shaped electrodes including electrode fingers.

Abstract: A filter circuit includes: a first transmission filter connected between a first antenna terminal and a first transmission terminal; a second transmission filter connected between the first antenna terminal and a second transmission terminal; a first reception filter connected between a second antenna terminal and a first reception terminal, the second antenna terminal being connected to an antenna different from an antenna to which the first antenna terminal is connected; and a second reception filter connected between the second antenna terminal and a second reception terminal.

Abstract: An acoustic wave device includes: a support substrate; a first piezoelectric substrate bonded to a first principal surface of the support substrate, the first piezoelectric substrate being a single crystal substrate, a first acoustic wave resonator located on an opposite surface of the first piezoelectric substrate from a surface to which the support substrate is bonded, the first acoustic wave resonator including an IDT; a second piezoelectric substrate bonded to a second principal surface of the support substrate opposite from the first principal surface, the second piezoelectric substrate being a single crystal substrate; and a second acoustic wave resonator located on an opposite surface of the second piezoelectric substrate from a surface to which the support substrate is bonded, the second acoustic wave resonator including an IDT.

Abstract: An acoustic wave device includes: a piezoelectric substrate that is made of a single crystal piezoelectric material, and includes a first region including an upper surface, and a second region that is located under the first region and has a density less than a density of the first region; and an IDT located on the upper surface of the piezoelectric substrate.

Abstract: An acoustic wave filter includes: series resonators connected in series between input and output terminals; and lines connected in parallel to the series resonators, wherein at least one of the lines includes: a first resonator including a piezoelectric substance, and first lower and upper electrodes sandwiching the piezoelectric substance in a c-axis orientation direction of the piezoelectric substance; a second resonator that is connected in series to the first resonator, and includes another piezoelectric substance, and second lower and upper electrodes sandwiching the another piezoelectric substance so that one of the second lower and upper electrodes in the c-axis orientation direction have an electric potential equal to that of one of the first lower and upper electrodes in the c-axis orientation direction; and a capacitor connected in parallel to one of the first and second resonators and not connected in parallel to another one of the first and second resonators.

Abstract: A method of fabricating an acoustic wave device includes: forming a piezoelectric thin film resonator and a second lower electrode on a substrate, the piezoelectric thin film resonator having a resonance region in which a first lower electrode and a first upper electrode face each other across a piezoelectric film, the piezoelectric film and the first upper electrode are not formed on the second lower electrode outside the resonance region; forming a first dielectric film in the resonance region and a second dielectric film on the second lower electrode outside the resonance region at a same time, the first dielectric film and the second dielectric film being made of a material different from a material of the piezoelectric film; and forming a second upper electrode on the second dielectric film, the second upper electrode facing the second lower electrode.

Abstract: An acoustic wave device includes: a piezoelectric substrate; a comb-shaped electrode located on the piezoelectric substrate; a pair of reflectors located on the piezoelectric substrate, the pair of reflectors sandwiching the comb-shaped electrode; a first dielectric film located on the piezoelectric substrate, the first dielectric film covering the pair of reflectors and having side surfaces in regions between the comb-shaped electrode and the pair of reflectors; and a second dielectric film located on the piezoelectric substrate, the second dielectric film covering the comb-shaped electrode and being in contact with the side surfaces of the first dielectric film.

Abstract: An acoustic wave device includes: a support substrate; a first piezoelectric substrate bonded to a first principal surface of the support substrate, the first piezoelectric substrate being a single crystal substrate, a first acoustic wave resonator located on an opposite surface of the first piezoelectric substrate from a surface to which the support substrate is bonded, the first acoustic wave resonator including an IDT; a second piezoelectric substrate bonded to a second principal surface of the support substrate opposite from the first principal surface, the second piezoelectric substrate being a single crystal substrate; and a second acoustic wave resonator located on an opposite surface of the second piezoelectric substrate from a surface to which the support substrate is bonded, the second acoustic wave resonator including an IDT.

Abstract: A multiplexer includes: a first chip that has a first filter and a resonator, the first filter being connected between a common terminal and a first terminal, a first end of the resonator being connected to the common terminal not via the first filter; and a second chip that has a second filter, the second filter being connected between a second end of the resonator and a second terminal and having a pass band lower than that of the first filter, a resonance frequency of the resonator being higher than the pass band of the second filter.

Abstract: An acoustic wave device includes: a piezoelectric substrate that is made of a single crystal piezoelectric material, and includes a first region including an upper surface, and a second region that is located under the first region and has a density less than a density of the first region; and an IDT located on the upper surface of the piezoelectric substrate.

Abstract: An acoustic wave device includes: a support substrate; a piezoelectric substrate; and a cap substrate, wherein the cap substrate includes a first region located along an outer peripheral portion of the cap substrate, a second region located along an inside of the first region and having a thickness less than a thickness of the first region, and a third region located inside the second region and having a thickness less than a thickness of the second region, and a surface of the first region is bonded to the surface of the outer peripheral portion of the support substrate, a surface of the second region is bonded to a surface of an outer peripheral portion of the piezoelectric substrate, and a surface of the third region is located away from a surface of the piezoelectric substrate to form a space for the excitation electrode to vibrate.

Abstract: An acoustic wave filter includes: series resonators connected in series between input and output terminals; and lines connected in parallel to the series resonators, wherein at least one of the lines includes: a first resonator including a piezoelectric substance, and first lower and upper electrodes sandwiching the piezoelectric substance in a c-axis orientation direction of the piezoelectric substance; a second resonator that is connected in series to the first resonator, and includes another piezoelectric substance, and second lower and upper electrodes sandwiching the another piezoelectric substance so that one of the second lower and upper electrodes in the c-axis orientation direction have an electric potential equal to that of one of the first lower and upper electrodes in the c-axis orientation direction; and a capacitor connected in parallel to one of the first and second resonators and not connected in parallel to another one of the first and second resonators.

Abstract: An acoustic wave device includes: a first chip that includes a first substrate, and a first filter formed on a first surface of the first substrate; and a second chip that includes a second substrate, and a second filter formed on a second surface of the second substrate, the second surface being located in a plane different from the first surface.

Abstract: An electronic device includes: a wiring substrate; a plurality of device chips that are flip-chip mounted on an upper surface of the wiring substrate through bumps, have gaps which expose the bumps between the device chips and the upper surface of the wiring substrate, and include at least one device chip that has a substrate having a thermal expansion coefficient more than a thermal expansion coefficient of the wiring substrate; a junction substrate that is joined to the plurality of device chips, and has a thermal expansion coefficient equal to or less than the thermal expansion coefficient of the substrate included in the at least one device chip; and a sealer that covers the junction substrate, and seals the plurality of device chips.

Abstract: An acoustic wave device includes: a support substrate; a piezoelectric substrate bonded on an upper surface of the support substrate at room temperature and made of a different material from the support substrate; a comb-shaped electrode formed on an upper surface of the piezoelectric substrate and exciting an acoustic wave; and an amorphous layer formed between the support substrate and the piezoelectric substrate.

Abstract: A composite electronic component includes: a circuit board; a package that includes an acoustic wave filter and is located on a top surface of the circuit board; a dummy package that is located on the top surface of the circuit board; and a lid that is located above the package and the dummy package.

Abstract: A filter circuit includes: a first band-pass filter, a second band-pass filter, a third band-pass filter and a fourth band-pass filter each having input and output terminals; a first terminal to which one of input and output terminals of first band-pass filter and one of input and output terminals of second band-pass filter are connected; a second terminal to which one of input and output terminals of third band-pass filter and one of input and output terminals of fourth band-pass filter are connected; a third terminal to which another one of input and output terminals of first band-pass filter and another one of input and output terminals of fourth band-pass filter are connected; and a fourth terminal to which another one of input and output terminals of second band-pass filter and another one of input and output terminals of third band-pass filter are connected.