Abstract: A ZT-cut quartz crystal resonator comprises two thin rectangular plates connected together by at least one resonant arm which itself is connected to a support zone by a linking bar. A pair of electrodes is provided on the quartz resonator for receiving alternating electrical signals of opposite polarity for effecting in-phase contour-mode vibration of the plates while making the arms to vibrate in opposite phase to the plates.

Abstract: The resonator according to the invention comprises at least one quartz crystal in the form of a rectangular thin plate, of which the length l is directed along an axis X', the width w along an axis Y' and the thickness t along an axis Z', and which vibrates in a contour mode. The axis Z' is situated in the plane of the electrical axis X and optical axis Z of the crystal and forms with the axis Z an angle .phi. such that16.degree.<.phi.<36.degree.and the axis Y' forms with the mechanical axis Y of the crystal an angle .theta. such that10.degree.<.theta.<30.degree.This resonator presents a zero temperature coefficient of the first order and is not dependent to any critical extent on the dimensional ratio between the sides w and l of the plate; the temperature coefficients of higher order are very small. The piezo-electric coupling is such that the optimized mode of oscillation is the only one excited in practice.