Theoretical study, modeling and realization of resonant gyroscopes with optical output

The theoretical study and the design of a micromachined resonant gyroscope are presented. A linear electro-mechanical model of the gyroscope has been developed, together with the calculations of the mechanical and electrical parameters. A standard CMOS technology has been considered for designing the micro-device thus allowing one to integrate the circuitry for the output signal conditioning. A novel metal-dielectric multilayer photonic band gap (PBG) stack, named "transparent metal", is deposited over the suspended proof mass surface in order to obtain an optical measure of motion normal to the device plane. This optical structure, deposited over the proof mass of the gyroscope, changes its transmission properties as a function of the air gap with a fixed plate, bonded over the die. The changes in the energy transmitted through this optical cavity allow one to measure the perpendicular motion with a very high sensitivity with respect to the classical approaches. Alternatively, a capacitive output can be considered by depositing a thick metal layer, instead of the stacked one, both over the moveable and the fixed plate. A comparison of the theoretical sensitivities is addressed together with the description of the first IC realization.