The Research Of Self-Excited Driving Circuit Of Micromachining Gyroscope

Silicon micromechanical gyroscope is a new type of inertial sensor developed in resent ten years, its sensing structure and interface circuit are mostly made of MEMS and micro-electronics technics, in both civil and military areas, it is studied widely and deeply for its broad foreground of evolution and application, because of its unique advantages such as small size,low cost and easy to volume-produce and so on. Based on the analysis of electrostatic drive and the dynamic character of the micromechanical gyroscope, the driving mode was researched, and the circuit of external AC voltage driving circuit and self-excited driving circuit was designed and simulated, Also the interface IC layout design and post layout simulation were introduced.Firstly, basing the theoretical of the micromachined vibratory gyroscope, we derived the equivalent electrical model of its driving mode. Using AC small signal analyse, the frequency response of vibration velocity of driving along with the input driving force was gained, the frequency which was the opposite of the max was the inherent frequency of driving mode, and was the same with the value of theory calculation; Using transient analyse, it was gained that the time would be longer of keeping vibration, if the damping coefficient was less; and the vibration of driving need same time to achieve stabilization, the time would be shorter, if the damping coefficient was bigger.And then, we researched the external AC voltage driving mode and self-excited driving mode, and analyzed the theory of self-excited driving stressly, determined the realizing method of self-excited driving circuit, and built circuit model with ideal parts of an apparatus, validated its feasibility by Hspice simulation.At last, two type of driving circuit were designed, every module was simulated and validated, and we simulated the self-excited driving circuit in Hspice combining the equivalent electrical model, validated its function; and we can see that the vibration frequency was the inherent frequency of driving mode, which was 2.7553kHz, the range was 1.2V, the frequency stability was 0.029%, the swing stability was 0.047%, satisfied the desire of sense structure of micromachined vibratory gyroscope with driving voltage。Realized the self-excited driving finally, and supplied guarantee for angle rate detecting.