A dual-axis MEMS vibratory gyroscope ASIC with 0.0061°/s/VHz noise floor over 480 Hz bandwidth

This paper presents a high performance dual-axis (pitch and roll) MEMS vibratory gyroscope readout ASIC which converts angular rate information to digital output. Two signal processing chains surrounding the MEMS sensor are implemented, namely the drive channel and the sense channel. The drive channel drives the sensor to resonate at its resonant frequency, which produces a velocity of the sensor disc to generate the Coriolis force during angular rotation. The sense channel employs a low noise trans-impedance amplifier (TIA) followed by a demodulator which down-converts the angular rate input signal from the resonant frequency to baseband. Two switched-capacitor (SC) 2-1 MASH delta-sigma ADCs convert the input angular rate from the pitch and roll arises to digital output. The reference of the ADC is also demodulated from the sensor output to cancel out supply voltage dependence. The whole ASIC including the high-voltage MEMS sensor driver, digital-filter, on-chip regulator and temperature sensor is fabricated in a 0.18pm CMOS technology with an area of 7.3 mm2. The design achieves a noise floor of 0.0032°/s/VHz and 0.0061°/s/VHz in full-scale input ranges of 500°/s and 2000°/s, respectively, over a 480Hz signal bandwidth. The bias instability is measured as 2.5°/h at input range of 500°/s. The whole ASIC consumes 7mA from a 3V supply.