Electromechanical Characteristics Analysis For The Novel Dual-drive RF MEMS Switch

As an important part of MEMS, RF MEMS switch can be widely applied to micro devices, such as phase shifter, filters, variable capacitors, resonators and some other radio frequency fields. At present, the problems that exist generally in RF MEMS are high voltage, small transmission power, long switching time and low reliability. The paper presents a novel dual-drive bistable RF MEMS switch with separate RF signal lines. The paper mainly includes the following contents.1. Based on the principles of MEMS technology and electrostatic actuation, a new kind of dual-drive RF MEMS switch model is established.2. The static equations are established and solved with numerical method,which achieves the deflection curves under different driving voltages. The results show that the minimum critical driving voltage of 26 V is required to achieve a 3μm’s maximum deformation.3. The kinetic equations are established and solved with numerical method. The influence of different size parameters on the switch closing time is analyzed. The simulations show that when the driving voltage is 26 V, the switching time is 31.5us, which decreases over the voltage. The speed and acceleration can respectively increase to 104m/s and 108m/s2. The switch can not be closed with a film thickness greater than 1μm and the membrane width is irrelevant to the dynamic response. Different materials of membranes have great influence on the dynamic characteristics, with the closed time Al< Au < Si <Si C.4. The dielectric material and sizes are optimized by carrying out an electromagnetic simulation with Ansoft HFSS software. The paper gets the conclusion: the thinner the thickness of the dielectric layer is, the better the isolation performs. Relative to a less impact on insertion loss, the thickness has a greater influence on the isolation, which is optimized to be 0.1μm. A material with high dielectric constant can effectively improve the RF performance. The final performance at 30 GHz is that the isolation of the switch is-32 d B and the insertion loss is-0.16 d B.