When applying an actuation voltage to the switch, the membrane actuated by the electrostatic force stays in the down position. The switch is at the ��off�� state, and the RF signal propagated in the signal line is coupled to the ground lines.Figure 1.Structure of DAPT secretase mechanism RF micromachined switch.Figure 2.Dimensions of (a) membrane; and (b) springs.The insertion loss and isolation of the RF switch depend on the flatness of membrane. To obtain excellent membrane flatness, this study adopts an annealing process to improve the residual stress of the membrane. The insertion loss and isolation of this work exceed that of the previous works [10,21]. In addition, the membrane has many etching holes as shown in Figure 2a, in order to reduce the etching time Inhibitors,Modulators,Libraries during the post-process.

The actuation voltage of the RF switch depends on the stiffness of springs. To reduce the stiffness of springs and obtain a lower actuation voltage, the springs are designed as S-shape.The FEM software CoventorWare was used to simulate the stress and displacement of the RF switch. According to the structure as shown in Figure 1 and the dimensions as shown in Figure Inhibitors,Modulators,Libraries 2, the model of the RF switch is established. The triangular element is adopted to mesh the model of the switch. The material of the switch is aluminum. The material properties of aluminum are mass density, 2,679 kg/m3; Young’s modulus, 70 GPa; Poisson’s ratio, 0.3 [22]. Figure 3 shows the relation between the membrane displacement and actuation voltage for the RF switch. The space between the membrane and the CPW lines is 4 ��m.

In this simulation, the actuation voltage changes from 0 to 14 V. The membrane displacement is 1.3 ��m when applying an actuation Inhibitors,Modulators,Libraries voltage of 13 V and the displacement is 4 ��m when applying an actuation voltage of 14 V. Therefore, the pull-in of the RF switch is about 14 V. Figure 4 displays the stress distribution of the switch with an actuation Inhibitors,Modulators,Libraries voltage of 14 V.Figure 3.Relation between actuation voltage and membrane displacement.Figure 4.Stress distribution of the RF switch.The simulation results reveal that the maximum stress of the RF switch is 38 MPa that locates at the anchored end of the springs. The maximum stress of the switch is below the yield strength of aluminum (124 MPa). Thereby, the deformation of the switch operates in the elastic range.

The characteristic impedance of the CPW lines was evaluated using the Agilent Brefeldin_A CAD tool. Figure 5 demonstrates the evaluated results of the characteristic impedance for the CPW lines. In this evaluation, the width and thickness of the signal line are 35 ��m and 0.53 ��m, respectively. The space between the signal and ground lines is 3.1 ��m. The results reveal that the selleckchem characteristic impedance of the CPW is 50.2 ��, and the value matches the impedance of 50 ��?in the network analyzer. This represents that the incident electromagnetic wave on the switch has a small return loss.Figure 5.