4–6.3 GHz microwave tunable filter employing RF MEMS switches

The low loss, high performance tunable micro-electromechanical filters have been investigated for ultra-wide band LNA and satellite communication applications. The 2-pole bandpass filter including two short folded resonators and two transmission zeros is considered. The folded resonators result in a small size of 2.4 × 2 mm². Three MEMS capacitors are used at the end of each resonator to tune the center frequency. The tuning range is from 4.14 GHz to 6.26 GHz with a bandwidth of 173 MHz to 265 MHz (4.4%). The results show an insertion loss of 0.72 dB and return loss more than 21 dB over the tuning range of 44%.