A Low-Noise High-G Closed-Loop Capacitive Accelerometer Using DC-Blocking Technique for Reduction of Power Dissipation

摘要

A novel fully-differential switched-capacitor interface using DC-blocking technique is presented for a ±30 g closed-loop capacitive micro-accelerometer. In view of the indispensable high-voltage feedback in a high-g large-mass closed-loop accelerometer resulting in a high power consumption, a charge sensitive amplifier with DC-blocking structure is utilized in the closed loop, separating the low-voltage sensing from high-voltage feedback and making most of loop modules work in the low-voltage domain. Moreover, owing to the DC-blocking structure, the switched-capacitor closed-loop system achieves a full-period feedback instead of the conventional time-multiplexing feedback, and the closed-loop system can therefore operate at a higher sampling frequency without increased working current, further reducing the aliasing noise. The interface designed in a 0.35 μm 3.3V/15V CMOS process occupies 9 mm^{2. The simulation results show that it consumes 12.77 mA from a 3.3-V supply and only 64.2 μA from a 15-V supply at a 1-MHz sampling clock, which is comparable to the power dissipation of low-g counterparts, and the dynamic range is 120.37 dB over a 200-Hz bandwidth.}