Capacitive Silicon Micro-accelerometer's Noise Reduction Technology Research

The capacitive silicon micro-accelerometer as an important inertia device, applied in the autocar, consumer electronics, inertial guidance and so on, which has a wide application prospect. Improving the detection accuracy of capacitive accelerometer has been an important research direction, which is the key to reduce the noise, the noise mainly include the mechanical thermal noise and noise of electric circuits. Noise reduction measures were described, for example, the design of sensitive units, high-frequency carrier frequency range selected, the choice of amplifier operation and so on, to reduce noise and improve sensitivity. Through the testing of the effect of noise, the sensitivity is better than the relevant reports.

I. Introduction

Micro-Mechanical Accelerometers, abbreviated as MMA, use of the inertial force mass to measure the acceleration the instruments suffered, is one of the important mechanical quantity sensors, and first study of micro-mechanical inertial sensors^[1] The capacitive silicon micro-accelerometer, which is processed by micro-machining techniques, with the advantage of small size, light weight, low power consumption, has a broad application prospccts^[2]. Capacitive silicon micro-accelerometer's capacitance variation is very small, usually about F, the detection signal seriously affected by the temperature, stray capacitance, electromagnetic interference, so the circuit of converts it into a voltage signal output is very difficult to achieve. In fact, on the development process of silicon micro-machined acceleration, the noise reduction technology has been plagued problems to researchers. The smallest accelerometer can detect (sensitivity threshold) to decide by the system noise^[3]. Reduce the noise of accelerometer is the critical threshold of improving the sensitivity.