Micromachined Tuning Fork Gyroscope Interface Circuit

Based on MEMS manufacturing technology, the microgyroscopes are with advantages in small size, light weight, low cost, high reliability and have great prospects in various field compared with classical gyroscopes, In this paper, the interface circuit of the tuning fork microgyroscopes is studied. The gyroscope works in the principle of electrostatic forces driving and capacitance detecting. The main contents are as follows:1. From the theoretical analyze of the microgyroscopes, the mathematic model of microgyroscopes and interface circuit are established, which is simulated in Matlab to analyse the performances of the microgyroscopes and feasibility of the interface circuit, obtain its optimized parameters.2. The driving-circuit of microgyroscopes is researched and designed. The resonant frequency of mass is tracked by the phase locked loop and the resonant amplitude is controlled by the automatic gain controller. The circuit in form of PCB is implemented. The test result confirms our scheme.3. The detecting-circuit of microgyroscopes is researched and design. The PCB of the interface circuit is tested. From the output of the detecting circuit, it is found that the minimum detected dynamic capacitances are in the magnitude of fF.