MEMS-Based Tunable LC Bandstop Filter With an Ultra-Wide Continuous Tuning Range

This letter presents a new microelectromechanical system-based tunable LC filter that utilizes a tunable capacitor and a tunable inductor in a single device. An electrically floating metal plate is located between the tunable capacitor and the tunable inductor. As the floating metal plate is thermally moved and used commonly for both the capacitor and inductor, the device provides an ultra-wide continuous frequency tuning range by a simultaneous increase or decrease of the capacitance and inductance. The fabricated tunable LC filter showed a continuous frequency tuning ratio in excess of 127% in a range of 8.8 GHz to more than 20 GHz.