摘要:
为了获得高保真的电容式RF MEMS开关自驱动失效阈值功率模型,必须弄清开关膜片上电场分布的边缘场效应。由于受到边缘场效应的影响,在计算开关自驱动失效阈值功率时,不能使用开关与中心导体的正对面积(A)取代受到射频信号频率的开关膜片面积(ARF)。否则,会出现射频信号功率等效电压(Veq)的计算偏差。因此,使用Veq的计算值与开关膜片上的均方根电压值(VRMS)来表征ARF。从而构建一个优值(ARF/A)来表征开关膜片上电场分布的边缘场效应强度。采用HFSS软件构建开关自驱动失效3D电磁模型,针对同一种开关构型,通过仿真得到不同射频信号功率下和不同开关气隙高度下膜片上边缘电场的分布。并与优值计算结果进行比较,初步验证了使用该优值表征开关膜片上电场分布的边缘场效应强度的合理性。
Abstract:
In order to obtain the high-fidelity model of self-actuation failure threshold power of the capacitive RF MEMS switch, it is necessary to clear the fringing field effect of the electric field distribution on switch membrane. The area of the switch membrane subjected to RF signal power (ARF) cant be replaced with the switch area over the center conductor (A) in the calculation of expression of self-actuation failure threshold power (Pact) of the switch, because of the influence of the fringing field effect. Otherwise, the deviation of calculation will occur in the RF signal power equivalent voltage (Veq). Therefore, ARF is characterized by using the ratio between the calculated Veq and the Root-Mean-Square voltage (VRMS) of the switch membrane. And ARF/A, a figure of merit (FoM), is constructed to characterize the intensity of the fringing field effect of the electric field distribution on the membrane. The 3D electromagnetic model of self-actuation failure of the switch is constructed using the HFSS (High Frequency Structure Simulator) code. Through the simulation, the distribution of fringing electric field on the membrane in variety of RF signal power (Pin) and air gap of the switch (g0) for the case of a common configuration of the switch is obtained. By comparing the calculation value of FoM and simulation results, the feasibility of using ARF/A, the FoM, to characterize the intensity of the fringing field effect of the electric field distribution on the membrane is preliminarily validated.
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