A Packaged THz Shunt RF MEMS Switch With Low Insertion Loss

This paper demonstrates a packaged THz shunt capacitor micro-electromechanical systems (MEMS) switch with low insertion loss. In-line shunt switch is used to achieve a low loss in THz band, which is realized by reducing the equivalent parallel inductance of switch. The equivalent circuit of the switch is analyzed systematically, the equivalent resistance is obtained based on the skin effect of high frequency current on the conductor and the current density distribution characteristics of the conductor cross-section. The equivalent capacitance is obtained by using "double microstrip" characteristic impedance calculation method, and the correction factor ( \Delta ) is introduced to calculate the equivalent inductance accurately. By optimizing equivalent circuit parameters and switch sizes, the structure of MEMS switch with low loss and high isolation characteristics are achieved. The switch is packaged by rectangular waveguide and achieved a low insertion loss. The comparison between the switch simulation results and the equivalent circuit simulation results verify that the parameter extraction method and circuit analysis are correct. The packaged MEMS switch is measured, and the results are in an acceptable agreement with simulation, the switch is actuated under voltage of ~30V. The measured result has achieved a low insertion loss with less than < 2dB from 220 to 280GHz, and isolation with ~16 dB from 240GHz to 320GHz in the "down" state.