Complete Analysis of a Novel Fully Symmetric Decoupled Micromachined Gyroscope

This paper reports on a novel fully symmetric decoupled micromachined gyroscope (FSDMG). The proposed sensor has five masses, electrostatically driven to primary mode oscillation, and senses, capacitively, the output signal. The new structure achieves complete decoupling between drive and sense modes to minimize the mechanical crosstalk, thanks to the intermediate mass and decoupling beams. The fully symmetric structure helps to lower the zero rate output of the sensor. The manufacturing asymmetry can be overcome by four sets of adjustable electrodes surrounding the outer frame. Drive and sense amplitudes, mechanical and electrical sensitivities, quality factor and approximated bandwidth are extracted analytically and results are confirmed using finite element analysis (FEA). The designed sensor shows drive and sense modes resonance frequencies of 6391 Hz and 6393 Hz respectively; the frequency mismatch is lower than 0.03%. The drive and sense capacitance are 0.098 pF and 0.23 pF respectively. The FEA using ANSYS shows drive and sense frequency of 6187and 6199 Hz respectively for only 0.2% mismatch in resonance frequency. The output signal achieves 70 nm amplitude for 1 deg/s input rotation rate, which results in 0.83 aF change in the sense capacitance. The numerical value of both the mechanical and electrical sensitivities are 0.07 mum/(deg/s) and 17.5 mV/(deg/s) respectively