Comparative analysis and tests for an improved frequency tuning area-varying electrode considering the influence of fringe capacitance

In this paper, an improved area-varying tuning electrode with better immunility to fringe capactor is proposed, analyzed and tested, which is mainly used for frequency tuning of micromechanical gyroscopes. Based on the existing area-varying tuning electrode Hu et al (2013 J. Microelectromech. Syst. 22 909-18), this paper firstly analyzes the capacitance of the tuning electrode, and obtains the relationship between the capacitance and the displacement using both the analytic formula and finite element analysis, verifying that the fringe capacitance in area-varying tuning electrode decreases the tuning ability of both up-tuning electrode and down-tuning electrode. Then, parametric scanning method is used to optimize the geometry parameter of the tuning electrode, which reduces the influence of fringe capacitance and increases the tuning ability of the tuning electrode. Contrast experiments and tests are carried with gyroscope samples with tuning electrodes before and after optimizing. The tested mean value of tuning ability of the improved tuning electrode is improved by 95.7% after opimization.