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In this paper, the design, implementation and characterization of a continuous time transimpedance-based ASIC for the actuation and sensing of a high-Q MEMS tuning fork gyroscope (TFG) is presented. A T-network transimpedance amplifier (TIA) is used as the front-end for low-noise, sub-atto-Farad capacitive detection. The T-network TIA provides on-chip transimpedance gains of up to 25 MOmega, has a measured capacitive resolution of 0.02 aF/radicHz at 15 kHz, a wide dynamic range of 104 dB in a bandwidth of 10 Hz and consumes 400 muW of power. The CMOS interface ASIC uses this TIA as the front-end to sustain electromechanical oscillations in a MEMS TFG with motional impedance greater than 10 MOmega. The TFG interfaced with the ASIC yields a two-chip angular rate sensor with measured rate noise floor of 2.7deg/hr/radicHz, bias instability of 1deg/hr and rate sensitivity of 2 mV/deg/s. The IC is fabricated in a 0.6-mum standard CMOS process with an area of 2.25 mm2 and consumes 15 mW.
Date of Publication: Aug. 2007