An acoustic wave device includes a piezoelectric layer, an interdigital transducer, and a slow wave propagation overlay over a portion of the interdigital transducer. By providing electrode fingers of the interdigital transducer such that a portion of the width thereof is dependent on an electrode period, a desirable wave mode may be maintained in the acoustic wave device. Further, by varying a width of the slow wave propagation overlay based on the electrode period, the desirable wave mode may be further maintained.

In a resonator is provided that suppresses a shift of a resonant frequency. The resonator includes a vibration portion that has a base with front and rear ends and multiple vibration arms with fixed ends connected to the front end of the base and that extend away from the front end. Moreover, the resonator includes a frame that at least partially surrounds the vibration portion and one or more holding arms provided between the vibration portion and the frame with first ends connected to the base and the second ends connected to a region of the frame at the front end side relative to the rear end of the base portion.

A surface acoustic wave device is disclosed. The surface acoustic wave device can include a support substrate, a piezoelectric structure that includes a first region having a first thickness, a second region having a second thickness different from the first thickness, and a third region sloped between the first region and the second region, a first surface acoustic wave element that is positioned in the first region, and a second surface acoustic wave element that is positioned in the second region.

A resonator is provided that suppresses frequency variations with etching without decreasing the strength of vibration arms. The resonator includes a base portion, a first vibration portion extending from the base portion in a first direction and having a first width, and a second vibration portion extending from the base portion in the first direction with a first gap between the first and second vibration portions and having the first width. The first and second vibration portions perform out-of-plane bending vibration with opposite phases at a predetermined frequency. The predetermined frequency varies in accordance with the first width and the first gap. The ratio of the first gap to the first width is within a range that causes an absolute value of rates of variations in the predetermined frequency with respect to variations in the first width and in the first gap to be not more than about 100 ppm.

A frequency adjustment method is provided for a piezoelectric resonator including a first vibrator, a second vibrator, a third vibrator, and a supporting portion. The second and the third vibrators connect to ends positioned along a vibration direction of a width-longitudinal mode in the first vibrator. The supporting portion is connected to two ends positioned along a vibration direction of the length-longitudinal mode in the first vibrator. The method includes: setting the second vibrator to a first region, a second region, and a third region along the vibration direction of the width-longitudinal mode; setting the third vibrator to a first region, a second region, and a third region along the vibration direction of the width-longitudinal mode; and performing the frequency adjustment by reducing or adding mass of at least one of the first region and the third region in each of the second vibrator and the third vibrator.

A microelectromechanical resonator device is provided having two-dimensional resonant rods. The resonator device has a piezoelectric layer formed with a plurality of alternating rods and trenches. A bottom electrode is in contact with a bottom surface of the piezoelectric layer. A top electrode metal grating of conductive strips is aligned in contact with corresponding rods of the piezoelectric layer.

A mesa-shaped piezoelectric resonator element including a resonator section having a thicker thickness than a peripheral section on the board surface of a piezoelectric substrate formed in a rectangular shape, wherein, when the length of the long side of the piezoelectric substrate is x and the board thickness of the resonator section is t, etching depth y of a level-difference section is set to fulfill a relationship in the following equation, based on the board thickness t. $y=-1.32\left(\frac{x}{t}\right)+435\left(\%\right)$

Aspects and embodiments disclosed herein include a radio frequency filter comprising a plurality of series bulk acoustic wave resonators and a plurality of shunt bulk acoustic wave resonators, the plurality of series bulk acoustic wave resonators and the plurality of shunt bulk acoustic wave resonators configured and arranged to generate acoustic waves at both fundamental tones and second overtones and to suppress signals associated with the acoustic waves at the fundamental tones, a passband of the radio frequency filter with a lowest insertion loss defined by the acoustic waves generated at the second overtones of the plurality of series bulk acoustic wave resonators and the plurality of shunt bulk acoustic wave resonators.

Aspects and embodiments disclosed herein include a radio frequency filter comprising a plurality of series bulk acoustic wave resonators and a plurality of shunt bulk acoustic wave resonators, at least one of the plurality of shunt bulk acoustic wave resonators exhibiting a different electromechanical coupling coefficient than at least one of the plurality of series bulk acoustic wave resonators, at least one of the bulk acoustic wave resonators exhibiting a higher electromechanical coupling coefficient than another one of the bulk acoustic wave resonators having a thicker piezoelectric material layer stack than the another one of the bulk acoustic wave resonators.

An oscillator master board includes a frame, oscillators and connecting portions. The frame includes an outer frame and connecting frames that are disposed within the outer frame and that are connected to the outer frame. The connecting frames extend along a first direction and are spaced apart from each other along a second direction that intersects the first direction. The oscillators are spaced apart from each other. Each of the oscillators is disposed adjacent to a corresponding one of the connecting frames and includes an oscillator substrate, a top frame, a top electrode unit and a back electrode unit. The connecting portions are disposed to connect the oscillators to the connecting frames. Each of the oscillators is connected to the corresponding one of the connecting frames through at least a corresponding one of the connecting portions. A method for making the oscillator master board is also provided.