Designing of a micromachined gyroscope system with a closed-loop DC biased interface ASIC

• Published in: Science China. Information sciences Vol. 57; no. 10; pp. 196 - 208
• Main Authors: Tao, TingTing, Lu, WenGao, Fang, Ran, Zhang, YaCong, Chen, ZhongJian, Yan, GuiZhen
• Format: Journal Article
• Language: English
• Published: Heidelberg Science China Press 01.10.2014; Springer Nature B.V
• Subjects: ASIC芯片; ASIC设计; Buffers; Closed loops; Computer Science; Electric power supplies; Information Systems and Communication Service; Low noise; Micromachining; Phase demodulation; Research Paper; Topology; Vibratory gyroscopes; 微机械陀螺仪; 电荷灵敏放大器; 直流偏置; 系统; 闭环; 高压输出; MEMS gyroscope; closed-loop oscillation; 闭环振荡; ASIC; 电容检测; 微机械陀螺仪; capacitance detection; 升压缓冲; high voltage buffer; 102403; 专用集成电路
• ISSN: 1674-733X; 1869-1919
• DOI: 10.1007/s11432-014-5167-8

In this paper, a micromachined gyroscope system composed of a vibratory gyroscope with its in- terface ASIC is presented. The system adopts a DC sensing method to detect the capacitive motion, which is insensitive to the mismatch of the gyroscope capacitors and can eliminate high frequency signals from the chip. Therefore it offers a commendable noise performance with simplified topology. Low noise design can be achieved by a continuous-time charge sensitive amplifier with the input-referred noise voltage of 9.833 nV/rtHz at 10 kHz. A novel high voltage （HV） buffer is adopted in the drive mode to strengthen its drive signal, so that the common-mode voltage of it is made at 5 V that is compatible with the gyroscope. The HV buffer utilizes two sets of power supply to achieve both good noise performance and HV output. The ASIC chip is fabricated in the 0.35 μm 2P4M BCD HV process, and is 2.5×2.0 mm2 in dimension. The test results prove that the system achieves a stable closed-loop oscillation in the drive mode. Furthermore, the in-phase demodulation result of the gyroscope system achieves a nonlinearity of 0.14% within the sense range of 0° 500°/s.