A vibration device that includes a vibration portion, a support portion connected to the vibration portion, a bending-vibrating portion connected to the support portion, and a frame-shaped base portion connected to the bending-vibration portion and disposed so as to surround the vibration portion. The base portion defines a slit that extends in a first direction crossing a second direction in which the support portion extends from the vibration portion, the slit defining first and second fixed ends of the bending-vibrating portion and which are continuous with the base portion. A length between a portion of the bending-vibrating portion connected to the support portion to one of the first and second fixed ends of the bending-vibrating portion is in a range of /8 to 3/8, where denotes a wavelength of a bending vibration corresponding to a frequency of a characteristic vibration of the vibration portion.

Various embodiments may relate to a resonator. The resonator may include a support including a substrate portion, and a membrane portion extending from the substrate portion over a cavity. The resonator may also include a piezoelectric layer on the membrane portion. The resonator may further include an electrode on the piezoelectric layer. The substrate portion may include dopants of a first conductivity type. The membrane portion may include dopants of a second conductivity type different from the first conductivity type. A ratio of a thickness of the membrane portion to a combined thickness of the electrode and the piezoelectric layer may be above 3:1 for temperature compensation.

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 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 piezoelectric resonator is provided that includes a piezoelectric element having first and second main surfaces; a first electrode including a first excitation electrode on the first main surface and a first extended electrode coupled to a first outer peripheral portion of the first excitation electrode; and a second excitation electrode provided on the second main surface. At least one cavity is in at least one of the first electrode and the second excitation electrode in the region where the first electrode overlaps the second excitation electrode and is within a range of a distance of four times or less a thickness of the piezoelectric element from a boundary between the first excitation electrode and the first extended electrode.

Various embodiments may relate to a resonator. The resonator may include a support including a substrate portion, and a membrane portion extending from the substrate portion over a cavity. The resonator may also include a piezoelectric layer on the membrane portion. The resonator may further include an electrode on the piezoelectric layer. The substrate portion may include dopants of a first conductivity type. The membrane portion may include dopants of a second conductivity type different from the first conductivity type. A ratio of a thickness of the membrane portion to a combined thickness of the electrode and the piezoelectric layer may be above 3:1 for temperature compensation.