Noise model considering electrical feed-through under force rebalance closed-loop detection of MEMS gyroscope

Abstract

This study analyses the transfer path of electrical feed-through noise in the electromechanical amplitude modulation detection circuit of a micro-electro-mechanical system vibrating gyroscope. By considering the feed-through, circuit and mechanical thermal noises, a new noise model in the force-to-rebalance closed-loop detection is constructed, and the expression of the noise-equivalent rotation rate spectrum is given. In addition, the influences of factors such as circuit gain, feedback coefficient and frequency split on the contribution of noise are analysed. The analysis shows that the back-end injection noise is the main factor affecting angle random walk (ARW) for high Q-value gyroscopes. Through actual measurements, it was found that the feed-through noise at the carrier frequency of the feedback circuit was the main source of the back-end noise. After noise optimization, the ARW of the detection output decreased from 0.148 to 0.017 , which was an improvement of about 8.7 times.