A 104-dB Dynamic Range Transimpedance-Based CMOS ASIC for Tuning

Abstract

In this paper, the design, implementation and charac- terization of a continuous time transimpedance-based ASIC for the actuation and sensing of a high- 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 M /10, has a measured capacitive resolution of 0.02 aF/ Hz at 15 kHz, a wide dynamic range of 104 dB in a band- width of 10 Hz and consumes 400 W of power. The CMOS inter- face ASIC uses this TIA as the front-end to sustain electromechan- ical oscillations in a MEMS TFG with motional impedance greater than 10 M /10. The TFG interfaced with the ASIC yields a two-chip angular rate sensor with measured rate noise floor of 2.7 /hr/ Hz, bias instability of 1 /hr and rate sensitivity of 2 mV/ /s. The IC is fabricated in a 0.6- m standard CMOS process with an area of 2.25 mm/50and consumes 15 mW.