A simple low cost scheme for closed loop operation of MEMS capacitive accelerometer

This paper presents a simple and low cost scheme for closed loop operation of MEMS capacitive accelerometer. The in-house developed accelerometer consists of a Silicon on Insulator (SOI) based comb drive structure integrated on a PCB with capacitance signal conditioning ASIC. A simple PI type controller designed using basic components like resistors, capacitors and op-amps are externally incorporated. The self test arrangement in MEMS structure has been successfully utilized for applying feedback voltage to operate the device in a closed loop configuration. The proposed scheme is shown to be a simple and cost effective approach for driving similar open loop MEMS accelerometers in a closed loop configuration. Further, the experimental results for both open loop and closed loop arrangement are shown to agree well with their corresponding simulated responses.