Reconfigurable multimodal bandpass filter based on RF-MEMS switchable CPW air-bridges

In this paper, a uniplanar RF-MEMS second-order bandpass filter with reconfigurable centre frequency is presented. It is based on quarter-wavelength slotline resonators and CPW-slotline multimodal immittance inverters (MIIs), which are reconfigured using RF-MEMS switchable CPW air-bridges (SABs). The filter can be adequately explained and designed using multimodal theory and circuit models. A surface micromachining process on high-resistivity silicon substrate was used to fabricate the filter. Experimental results show frequency reconfigurability from 12 GHz to 13 GHz, maintaining the same relative bandwidth, and insertion losses of 4.6 dB and 4.7 dB respectively.