Development of RF MEMS Switches for High Power Applications

This paper introduces a new concept in RF MEMS switches intended for high RF signal power applications at millimetre-wave operation. The novel SPST switch architecture employs electrothermal hydraulic microactuators. Out-of-plane silicon levers, having spring action and latching mechanisms, have been designed to create an OFF-state gap separation distance of 250 μm between ohmic contact electrodes. Having simple assembly, many of the inherent problems associated with the more traditional suspension bridge and cantilever beam type architectures can be overcome. In principle, low ON-state insertion loss, high OFF-state isolation and high RF signal power handling characteristics can be achieved with careful design. Using Ansoft`s HFSS software, a 40 to 60 GHz prototype was developed. The simulated ON-state insertion loss and return loss are 1.2 dB and 23.8 dB, respectively, at 50 GHz; while OFF-state isolation is 30.1 dB at 50 GHz. Preliminary small-signal measurements, from DC to 8.5 GHz, show encouraging results.