Fringe Capacitance Analysis of Micro Devices
Date Issued
2006
Date
2006
Author(s)
Ou, Tsung-Hua
DOI
zh-TW
Abstract
This research aims at developing a general solution for calculating the capacitance of fringe field precisely. Capacitive sensing and electrostatic actuating devices are commonly used on microdevices. Therefore, determination of the capacitance is critical in the design to determine the performances of such devices. Accurate determination of capacitance is very challenging in virtue of the fringing field. The finite element method (FEM) is often used for calculating the capacitance as lacking precision analytical model. FEM has been implemented in various commercial MEMS simulation software such as ANSYS, COMSOL, CovnetorWare, and Intellisuite. However, FEM has the disadvantages of un-explicit physical meaning and requiring massive numerical calculations, and therefore is not easy to carry out the parametric study of capacitive devices. This research develops an analytical solution for calculating the three-dimensional fringe field capacitance of paralleled-plate-type capacitors, which is the commonest structure. The analytical solution is derived from the conformal mapping method and simplified by some approximate approaching techniques. The present analytical solution shows very high accuracy within one-percentage error comparing with the experimental results and the numerical simulation by ANSYS. By the present high precision analytical solution, one can easily evaluate the capacitance in few seconds by manual work.
Subjects
邊緣電容
微機電電容
電容感測
保角映射轉換
微機電元件
Fringe Field Capacitance
MEMS Capacitor
Capacitance Sensing
Conformal Mapping
Micro-devices
Type
thesis
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