Design and Modeling of Decoupled and Tunable Bandwidth (40-330 Hz) MEMS Vibratory Gyroscopes

This thesis reports on the design and modeling of decoupled and tunable bandwidth MEMS vibratory gyroscopes that were designed for the medical applications of tremor compensation and micro-surgical tool navigation. Two different designs are presented. The first design is a dual mass de-coupled gyroscope that consists of a drive and sense mass implemented in a drive frame architecture. The device achieves a theoretical maximum resolution of 0.01 deg/s and a maximum sensitivity of 5.247 \u83F/deg/s. However, this design is prone to quadrature error that drastically reduces the sensitivity of the device and completely destroys its performance. The second design is a three-mass doubly-decoupled gyroscope that consists of a drive, Coriolis and sense mass and is designed to overcome the sensitivity of the dual mass de-coupled gyroscope to quadrature error. The three-frame structure of this gyroscope, with an outer sensing frame, leads to an improved electrical sensitivity over conventional architectures. It leads to a full decoupling between the sense and drive modes that makes the device robust against quadrature error and eliminates the cross axis sensitivity that usually limits the angular rate sensing performance. The device achieves a theoretical maximum resolution of 0.006 deg/s and a maximum sensitivity of 1.255 \u83F/deg/s. Optimizing this design based on the DVA principle leads to a 60 % reduction in the size of the Coriolis mass, resulting in a 37 % increase in the resolution and an 19 % increase in the sensitivity. The drive and sense mode resonance frequencies of the designs are 2500 Hz and 2830 Hz respectively, with an input angular rate bandwidth tunable between 40Hz and 330Hz. Both COMSOL finite element simulations and macro models implemented in Agilent ADS were used to validate the structures.Electronic InstrumentationMicroelectronicsElectrical Engineering, Mathematics and Computer Scienc