Wideband tunable Love wave filter using electrostatically actuated MEMS variable capacitors integrated on lithium niobate

A tunable bandpass filters with low insertion loss, sharp cut-off characteristics, wide bandwidth and wide tunability is strongly expected for future reconfigurable and cognitive wireless systems. In this study, a wideband tunable filter with the center frequency of 1.08 GHz was fabricated by directly integrating Love wave resonators and electrostatically actuated MEMS variable capacitors on a 15° Y LiNbO3 wafer. The Love wave resonators have an extremely large electromechanical coupling coefficient (k2 ∼ 30%), providing wide bandwidth and wide tuning range. The 3 dB bandwidth was tuned from 146 MHz to 130 MHz by applying 15 V to one of the MEMS variable capacitors.