Abstract
This paper presents a MEMS (Micro-Electro-Mechanical System) Silicon Oscillating Accelerometer (SOA) with AC (alternating current) polarization to expand its bias-instability limited by the up-converted 1/f noise from front-end transimpedance amplifier (TIA). In contrast to the conventional DC (direct current) scheme, AC polarization breaks the trade-off between input transistor gate size and white noise floor of TIA, a relative low input loading capacitance can be implemented for low noise consideration. Besides, a self-compensation technique combining polarization source and reference in automatic-gain-control (AGC) is put forward. It cancels the 1/f noise and drift introduced by the polarization source itself, which applies to both DC and AC polarization cases. The experimental result indicates the proposed AC polarization and self-compensation strategy expand the bias-instability of studied SOA from 2.58 μg to 0.51 μg with a full scale of ± 30 g, a 155.6 dB dynamic range is realized in this work.
Highlights
Nowadays, MEMS accelerometers are ubiquitous in automobile, consumer electronics and guidance/inertial navigation systems [1,2,3,4,5]
MEMS Silicon Oscillating Accelerometer (SOA) is essentially two resonators connected to a proof mass
We focus on the 1/f noise introduced by the front-end transimpedance amplifier (TIA) and polarization voltage, VDC
Summary
MEMS accelerometers are ubiquitous in automobile, consumer electronics and guidance/inertial navigation systems [1,2,3,4,5]. To acquire sufficient motional resistance, the resonant beam of a MEMS resonator is usually polarized to a DC level several times higher than the supply rail, which is generated by a DC charge pump This polarization voltage contains a large 1/f noise component and could be up-converted to oscillation amplitude. It has been reported that the MEMS resonator can be polarized by an AC source, which reduces the frequency drift introduced by charges on the associated capacitive electrodes [24,25] Such AC polarization technique is adopted in MEMS SOA to down-convert a 157.5 kHz oscillation frequency to 10 kHz; in this way, the bandwidth and noise requirement of front-end TIA is greatly reduced [26]. The experimental results of MEMS SOA with AC polarization are presented in Section 5, and Section 6 concludes the paper
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