MEMS Based Tunable Band-Stop Structure

The paper proposed a tunable band-stop structure consisting of a shunt connected series resonator. The tunable characteristics of the structure are possible due to the use of MEMS (Micro-Electro-Mechanical System) series connected to a CPW inductor. The tuning frequency range is analyzed taking into account the variable equivalent MEMS capacitance as well as the nonlinearity of the inductance versus the frequency and versus the CPW length. It is shown that the length of the CPW inductor is important over the tuning frequency range, obtaining 17.6-18.3GHz and 17-18.3GHz, for two CPW lengths (the wider frequency range, the smaller CPW length). The attenuation introduced by these structures varies in the range 8-13dB for the longer CPW length and 15-20dB for the shorter one, depending on the MEMS bridge displacement. If two identical structures are cascaded, the attenuation increases to 18-30dB and 38-60dB, respectively. The structures have been analyzed by using the IE3D-Zeland full-wave electromagnetic simulator.