A monolithic RF-MEMS filter with continuously-tunable center-frequency and bandwidth

A novel RF-MEMS structure to achieve tunable bandwidth is presented in this paper. A movable nickel electrode is employed to realize tunable broad-side coupling. The bottom electrode is fabricated with high resistivity-SiCr to avoid performance degradation. This tunable coupling section is implemented in a planar MEMS tunable filter that consists of λ/2 coplanar waveguide (CPW) resonators and nickel RF-MEMS varactors. The center frequency is tuned from 28.55 GHz to 27.22 GHz. The tuning range of the bandwidth is up to 5%. Simultaneous and continuous tuning of both center frequency and bandwidth is experimentally demonstrated.