Inductively tuned bulk micromachined RF MEMS switch with high isolation and improved reliability

In this paper, a reliable K-band RF MEMS shunt switch with high isolation is presented. The switch is fabricated on a high-resistivity silicon substrate (ρ = 10,000 Ω cm, εr = 11.7, h = 675 µm) using bulk micro-machined techniques. A novel symmetrical tri-layer sandwich (insulator–metal–insulator) concept is implemented in membrane design which results in stress-free membrane and thus results in lower actuation voltage of 15V. The inductive effect created in the CPW ground not only brings down the resonant frequency which eliminates the need to increase the membrane length but also improves the isolation (> 40 dB). This electrostatically actuated switch has measured insertion loss and isolation of 1.51 dB and 46.42 dB at 20.25 GHz, respectively. The switch shows consistent performance in terms of RF as well as mechanical after 8 h of continuous operation without stiction. The switch can have applications in telecommunication, defense and space-based phased array system, etc.