The study of a high-isolation single-pole-double-throw RF MEMS switch

In this paper, design, fabrication and measurements of a novel single-pole-double-throw three-state RF MEMS switch based on silicon substrate are presented. The RF MEMS switch consists of two UV-shaped beam push-pull thermal actuators which have three states of ON, OFF and Deep-OFF by using current actuation. When the switch is at Deep-OFF state, it can provide a higher isolation. The switch is fabricated by Metal-MUMPs process. The measurement results show that, to the proposed single-pole-double-throw RF MEMS switch, when Switch I is at the ON state and Switch II is at the OFF state, the return loss is better than -16 dB, the insertion loss of Portl and Port2 is less than -0.9 dB and the isolation of Port3 and Port1 is better than -22 dB at the frequency range from 8 GHz to 12 GHz. When Switch I is at the ON state and the actuator of Switch II is pulled back, which is called the Deep-OFF state, the return loss of Port1 is better than -15.5 dB, the insertion loss of Port1 and Port2 is better than -0.8 dB, and the isolation of Port3 and Port1 is better than -23.5 dB can be achieved at the frequency range from 8 GHz to 12 GHz.