Micromachined gyroscope design allowing for both robust wide-bandwidth and precision mode-matched operation

This paper presents a new z-axis gyroscope design with a 2-degree of freedom (DOF) sense mode allowing interchangeable operation in either precision (mode-matched) or robust (wide-bandwidth) modes. This is accomplished using a complete 2-DOF coupled system which, unlike the previous multi-DOF design, allows for the specification of the sense mode resonant frequencies and coupling independent of frequency. The robust mode corresponds to operation between the 2-DOF sense mode resonant frequencies providing a response gain and bandwidth controlled by frequency spacing. Precision mode of operation, however, relies on mode-matching the drive to the second, anti-phase sense mode resonant frequency which can be designed to provide a gain advantage over a similar 1-DOF system. Experimental rate characterization of an SOI prototype in air for both robust and precision modes revealed scale factors of 0.282 and 0.690 mV/deg/s respectively. The improvement due to precision mode operation is increased to 27 times for operation in 500 mTorr reduced pressure.