Ultra wide band elastic resonators and their application: SH0 mode plate wave resonators with ultra wide bandwidth of 29 %

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 tunable filters to simplify their circuits. This time, authors realized resonators with ultra wide bandwidths of 26 to 29 % and a large impedance ratio of 92 to 98 dB between resonant and anti-resonant frequencies using an SH
₀
plate wave in a LiNbO
₃
plate. In addition, a band pass type tunable filter with a tunable range of 16 to 18 % was realized using the resonators.