A Novel Design of Tunable Band-Stop Filter Using MEMS Technology

A novel design of tunable band-stop filter is presented using MEMS technology. The MEMS bridge is used as the moveable structure to tune the frequency of the band-stop filter. The basic cell is designed on the coplanar waveguide (CPW) transmission line. When the bridge is at up-state, the centre resonant frequency of the basic cell is 20.3 GHz. When the bridge is at down-state, the centre resonant frequency of the basic cell is 23.44 GHz. The 20 dB bandwidth reaches 2.87 GHz. Return loss is less than 0.5 dB in the stop-band. The band-stop filter is cascaded by three basic cells. It can be tuned from 23.4 to 18.2 GHz, when the MEMS bridge is changed from up to down state.