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This paper presents one kind of digital closed loop control system of MEMS (Micro Electro-Mechanical Systems) vibratory gyroscope, particularly concentrating on the sense mode of MEMS gyroscope. The controller consists of a sine wave source realized by CORDIC algorithm, multiplication demodulators, some low-pass filters and force feedback rebalance module. Compared with the open loop sense system of gyroscope, the closed loop sense system has larger measurement range and wider bandwidth. Besides, the sine wave source realized with CORDIC algorithm can save hardware resources. The digital system is demonstrated on a PCB with a FPGA on it. The test results show that the measurement range of the closed loop system can be increased to 3 times by the open loop, and the bandwidth can be extended to 262Hz from 27Hz of the open loop system.

In this paper, a silicon bulk micromachined lateral-axis tuning-fork gyroscope (TFG) with a decoupled comb drive and torsional sensing comb capacitors is presented. The novel driving comb capacitors are used to suppress the parasitic out-of-plane electrostatic force and, hence, can decouple the mechanical crosstalk from the sensing mode to the driving mode in a simple manner. The torsional sensing combs are designed to differentially sense the out-of-plane rotational moment and are arranged centroidally to be immune to fabrication imperfections for good linearity and electrostatic force balancing. The torsional sensing combs adopted in the TFG help to lower the air damping of the sensing mode while the driving mode of the gyroscope is dominated by slide-film air damping; hence, it can work even at atmospheric pressure. The process for this lateral-axis gyroscope can also be used to fabricate z-axis gyroscopes; therefore, low-cost miniature monolithic inertial measurement units can be realized without vacuum packaging. The TFG is tested at atmospheric pressure with a sensitivity of 17.8 mV/°/s and a nonlinearity of 0.6% in a full-scale range of 1000°/s. The bias stability is measured to be 0.05°/s (1 ?) in 30 min with an equivalent noise angular rate of 0.02°/s/Hz1/2.