Shear-mode plano or bi-convex quartz crystal - has specified thickness, dia., and radius of curvature for increased fundamental and unwanted harmonic suppression

摘要

The shear-mode quartz crystal, for producing overtones in the MHz region for a quartz stabilised oscillator has a plano or bi-convex shape with a maximum thickness of roughly 1700n/f millimeters, where f is the operating frequency in KHz and n the number of the wanted harmonic. The radius of curvature of the crystal is roughly 140 to 180 times the inverse of the max. thickness in the case of a planoconvex crystal and 280 to 360 times in the case of a biconvex crystal. The diameter of the crystal is 54/n to 72/n times the max. thickness.