SPDT RF MEMS switch using a single bias voltage and based on dual series and shunt capacitive MEMS switches

A coplanar waveguide (CPW) single-pole double-throw (SPDT) X-band RF MEMS switch that can be actuated between states by applying a single voltage is introduced. Since a signal can be transmitted to one of the output ports without biasing, this has the potential to reduce the complexity of the required biasing network. The switch consists of a series and a shunt capacitive MEMS switch separated by a quarter wavelength transmission line. The shunt switch section was fabricated and measured separately and shown to have an insertion loss of 0.25 dB and isolation of 33 dB at 10 GHz. A SPDT 3-port switch was fabricated and port isolations of about 15 dB and an insertion loss of 1 dB were obtained in the up-state. In the down-state, 40 dB of isolation with a 1 dB insertion loss were measured. The actuation voltage was 35 V.