Patent ID: 9013242
Filing Date: 2015-04-21
Classification: H01L,H03B,H03H

Abstract:
1. A resonator element comprising: a substrate including a first principal surface and a second principal surface respectively forming an obverse surface and a reverse surface of the substrate, and vibrating in a thickness-shear vibration mode; a first excitation electrode disposed on the first principal surface; and a second excitation electrode disposed on the second principal surface, and being larger than the first excitation electrode in a plan view, wherein the first excitation electrode fits into an outer edge of the second excitation electrode in the plan view, and the following relational expressions are fulfilled: where: M denotes an energy trap coefficient; K denotes an anisotropy factor of the substrate; hx denotes a length of the first excitation electrode along a thickness-shear vibration direction; ts denotes a thickness of the substrate; Δ denotes an amount of frequency drop; fs denotes a cut-off frequency of the substrate; fe denotes a frequency when the excitation electrodes are disposed on the substrate; R denotes a frequency constant of the substrate; te denotes a sum of a thickness of the first excitation electrode and a thickness of the second excitation electrode; te ρe denotes a density of the excitation electrodes; and ρx denotes a density of the substrate.