Design of the closed-loop capacitive micro-accelerometer based on PSpice

Traditional open-loop accelerometers cannot be used widely because of their low accuracy, small dynamic range and bandwidth. In order to satisfy the demand of large dynamic range, a closed-loop feedback control system capacitive accelerometer is designed. The closed-loop system is divided into six modules, which are the module of mechanical simulation, the module of C/V conversion, the module of phase-shifting, the module of modulation and demodulation, the module of low-pass filter and the module of PID control. The six modules are designed altogether and the whole system are simulated with PSpice, the results of which can illustrate the feasibility of the closed-loop feedback control. Through the results of analysis, we get a dynamic range of +/- 6.8g and find that the system can improve the dynamic range and working bandwidth of the accelerometer without compromising the sensitivity.