Wide band resonators using SH mode of plate wave on LiNbO3

Currently, an ultra wide band resonator to realize a tunable filter with a wide tunable range is strongly required, because a mobile phone with multi-bands and a cognitive radio system require such a tunable filter to simplify their circuits. This time, authors realized resonators with ultra wide bandwidths of 29 % and a large impedance ratio of 98 dB between resonant and anti-resonant frequencies using an SH₀ plate wave in a LiNbO₃ plate. In addition, by applying their resonators to tunable filters, a band pass type tunable filter with a tunable range of 15 % and a ladder type one with a tunable range of 19 % were realized using capacitance of capacitors connected them.