Influence of Fringing Field on Estimating of Comb-Drive Accelerometer Performance

In this paper we present the influence of omitting the fringing field in calculations on estimating of comb-drive accelerometer performance. Such sensor consist of many parallel plate capacitors that forms combs wherein electric field occurs also outside the overlapping area of fingers. Therefore, the real capacitance is larger than it results from the basic equation for parallel plate capacitor. Thus, the knowledge about the amount of underestimation is crucial when estimating the device performance. Three structures are analyzed: parallel plate capacitor, comb-drive structure and whole comb-drive accelerometer. The simulations include the influence of gap distance, the size of surrounding environment and the difference between calculated and real capacitance. In comparison analytical model and Comsol is used.