60-g FSR, 6-μg Stability FM Time-Switched Accelerometers Through Shaped Comb Fingers

The work presents a new design of a frequency-modulated (FM) in-plane accelerometer in which the frequency-tuning mechanism is implemented through shaped comb finger (SCF) electrodes. This approach releases the constraints on the travel range of the proof-mass antiphase mode, thus increasing the resonance current and, in turn, improving phase noise. The elementary tuning finger cell is optimized via electrostatic finite element models and is then incorporated into the main sensor design. Experimental data confirm the design validity, achieving almost an order of magnitude improvement in terms of noise: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {45\, \mu \text {g}/\sqrt {\text {Hz}}}$</tex-math> </inline-formula> velocity random walk and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {6\, \mu \text {g}}$</tex-math> </inline-formula> bias stability at 1000 s are achieved, while holding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\pm 60\, \text {g}}$</tex-math> </inline-formula> full-scale range, thus leading to 120 dB dynamic range on a 25-Hz bandwidth. Scale factor repeatability, offset drift in temperature and rejection of vibrations are also given attention, measured and discussed. [2025-0037]