A resonator assembly comprising a semiconductor substrate, a resonator gyroscope, the resonator gyroscope including a first resonator formed in a layer of a first material, and an oscillator on the semiconductor substrate, the oscillator including a second resonator formed of a second material, wherein the second resonator is attached in a cavity; the cavity comprising a first recess in said layer of a first material and the edges of the first recess being attached to the substrate, or the cavity comprising a second recess in said substrate and the edges of the second recess being attached to said layer of a first material.