Patent ID: 9013243
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 opposite to the first principal surface, and the substrate vibrating in a thickness-shear vibration mode; a first excitation electrode disposed on the first principal surface, and including a side or a circumference having an internal contact with an imaginary quadrangle; and a second excitation electrode disposed on the second principal surface, wherein assuming that an area of the quadrangle is S the following relationship is fulfilled: the second excitation electrode is larger than the imaginary quadrangle in a plan view, the following relationships are fulfilled:  where: M denotes an energy trap coefficient; K denotes an anisotropy coefficient 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; te2 denotes the thickness of the second excitation electrode; ρe denotes a density of the excitation electrodes; and ρx denotes a density of the substrate.