A Sub-0.1°/h Bias-Instability Split-Mode MEMS Gyroscope With CMOS Readout Circuit

• Published in: IEEE journal of solid-state circuits 2018-09, Vol.53 (9), p.2636-2650
• Main Authors: Zhao, Yang, Zhao, Jian, Wang, Xi, Xia, Guo Ming, Shi, Qin, Qiu, An Ping, Xu, Yong Ping
• Format: Article
• Language: English
• Subjects: Angle random walk (ARW); Automatic control; Bandwidth; Bias; bias instability (BI); Circuit design; Circuit stability; CMOS; CMOS readout circuit; Damping; Demodulation; demodulation phase; Digitization; Flicker; Gyroscopes; inertial navigation; low noise front end; MEMS gyroscope; Microelectromechanical systems; Micromechanical devices; Noise; Noise control; Power consumption; Random walk; Sensitivity; Sensitivity enhancement; Sensors; Stability; Temperature compensation; temperature drift
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2018.2844285

This paper describes a split-mode tuning fork MEMS gyroscope with CMOS readout circuit. The gyroscope achieves 0.008°/ \surd \text{h} angle random walk (ARW) and 0.08°/h bias instability (BI). The noise and phase requirements of the MEMS sensing element and the readout circuit are analyzed, from which the system-level design guidelines are proposed. The MEMS sensing element is optimized to enhance its mechanical sensitivity with reduced quadrature coupling and thermoelastic damping. Front ends with 5.9-fA/ \surd Hz input-referred current noise floor and less than 0.5° phase delay are achieved to reduce the gyroscope's ARW and thermal drift. A low flicker noise automatic amplitude control circuit and digitized phase-sensitive demodulation are adopted to improve the gyroscope's BI. After temperature compensation, the temperature coefficients (TCOs) of the scale factor and the zero-rate output are 27 ppm/°C and 1.7°/h/°C from −40 °C to +60 °C, respectively. The overall power consumption is 8.5 mW under a 3.3-V supply.