Acoustic filters, resonators and methods of making acoustic filters are disclosed. An acoustic resonator device includes a substrate. A back surface of a piezoelectric plate is attached to the substrate, a portion of the piezoelectric plate forming a diaphragm that spans a cavity in the substrate. A conductor pattern is formed on the front surface of the piezoelectric plate, the conductor pattern including an interdigital transducer (IDTs) with interleaved fingers of the IDT disposed on the diaphragm. A ratio of the mark of the interleaved fingers to the pitch of the interleaved fingers is greater than or equal to 0.2 and less than or equal to 0.3.

An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

An elastic wave device includes a supporting substrate, a high-acoustic-velocity film stacked on the supporting substrate and in which an acoustic velocity of a bulk wave propagating therein is higher than an acoustic velocity of an elastic wave propagating in a piezoelectric film, a low-acoustic-velocity film stacked on the high-acoustic-velocity film and in which an acoustic velocity of a bulk wave propagating therein is lower than an acoustic velocity of a bulk wave propagating in the piezoelectric film, the piezoelectric film is stacked on the low-acoustic-velocity film, and an IDT electrode stacked on a surface of the piezoelectric film.

An acoustic wave filter includes a substrate, a first resonator disposed on the substrate, a second resonator disposed on the substrate to be spaced apart from the first resonator, a connector electrically connecting the first and second resonators, and a variable capacitor formed in the connector to tune a pass band frequency of the acoustic wave filter.

An acoustic wave filter includes a substrate, a first resonator disposed on the substrate, a second resonator disposed on the substrate to be spaced apart from the first resonator, a connector electrically connecting the first and second resonators, and a variable capacitor formed in the connector to tune a pass band frequency of the acoustic wave filter.

When a thick frequency adjustment metal film of a tuning fork-type vibration piece is irradiated with a beam on a wafer for frequency coarse adjustment, projections are possibly formed on a roughened end of the frequency adjustment metal film. Such projections are pressurized and pushed down not to chip off under any impact, so that the risk of frequency fluctuations is suppressed.

When a thick frequency adjustment metal film of a tuning fork-type vibration piece is irradiated with a beam on a wafer for frequency coarse adjustment, projections are possibly formed on a roughened end of the frequency adjustment metal film. Such projections are pressurized and pushed down not to chip off under any impact, so that the risk of frequency fluctuations is suppressed.

A vibrator device includes: a base; a vibrator disposed in the base; and a lid including a substrate having a light transmitting property and a silicon substrate joined to the substrate and a part of the base surrounding the vibrator.

A vibrator device includes: a base; a vibrator disposed in the base; and a lid including a substrate having a light transmitting property and a silicon substrate joined to the substrate and a part of the base surrounding the vibrator.

A resonator comprising a piezoelectric film which creates an acoustic path that is slightly longer in a central region of the resonator than at an edge of the resonator.