Analysis and optimization of two movable plates RF MEMS switch for simultaneous improvement in actuation voltage and switching time

An attempt to overcome the existing limitations of RF MEMS switch like high actuation voltage and low switching time simultaneously has been addressed by introducing the concept of moving bottom plate (CPW central line).The performance characteristics of such MEMS switch with two movable plates has been analyzed by setting up the continuity equation of both the plates and solving it analytically with valid approximations. It is seen that for all practical cases such two movable plate designs can be represented by a single movable plate with equivalent membrane parameters. It is observed that a simultaneous reduction of both the actuation voltage and switching time around 20% is possible by optimizing the dimensions. Alternatively a maximum reduction of 30% in the actuation voltage is possible keeping the switching time unaltered and the switching time can be reduced by 50% keeping the switching voltage unaltered. Closed form expressions for the actuation voltage and switching time are obtained which are seen to match with the numerical results.