Abstract: Disclosed is a pass band type acoustic wave filter capable of obtaining an excellent attenuation characteristic in attenuation bands, in which an IDT electrode having a meander structure is used as at least one of the input-side electrode and the output-side electrode, and the attenuation band is provided over/under the pass band. An electrode having a meander structure in which a plurality of IDT blocks are connected to each other in series between the input port or the output port and the ground port is arranged as the input-side IDT electrode and the output-side IDT electrode, and the electrode finger between the neighboring IDT blocks is removed, so as to suppress excitation of an undesired acoustic wave.

Abstract: A method for fabricating a crystal unit, including a preparing step, a bonding step, and a separating step, is provided. The preparing step prepares a quartz plate and a supporting substrate with a recess that is larger than the vibrating region on a surface of the supporting substrate. The recess corresponds to a vibrating region in the crystal unit. The bonding step bonds the quartz plate to the surface of the supporting substrate such that the quartz plate is separated from the supporting substrate in the recess. The separating step separates the quartz plate into the vibrating region and the framing portion by performing dry etching on the quartz plate such that the quartz plate has a shape that connects the vibrating region to the framing portion via a supporting beam. The framing portion surrounds the vibrating region.