Analysis and design of a novel high capacitance ratio and low actuation voltage RF MEMS switch

Abstract

Analysis and design of a novel high on/off capacitance ratio and low actuation voltage radio frequency microelectro-mechanical systems (RF MEMS) switch. Circuit topology and electrode topology of RF MEMS switches are analyzed. In order to decrease actuation voltage, the switch, using coplanar waveguide transmission line for signal transmission, are designed with special elastic supported structures and actuation electrode are located on both sides of signal line. Metal–insulator–metal (MIM) fixed capacitors are used to change the up/down-state capacitance without adding more loss to the switches. Through the finite element method to determine the spring constant and the necessary applied voltage, the simulation voltage is 4.5 V. The RF performance are obtained by simulating results in the HFSS tool. The switch exhibits the insertion loss of – 0.2 dB, and isolation of – 20 dB within the range of 10–30 GHz, and the isolation extreme value reaches − 41 dB at resonant frequency, the return loss is less than − 12 dB at the resonant frequency. From the fitted results, the on/off capacitance ratio is 162 for the MEMS switch. Compared with traditional MEMS capacitive switches, the proposed MEMS switch exhibit high on/off capacitance ratios and low actuation voltage.