ACOUSTIC WAVE RESONATOR, FILTER AND MULTIPLEXER

To suppress spurious.SOLUTION: An acoustic wave resonator according to the present invention comprises: a piezoelectric substrate; a pair of comb-shaped electrodes which is provided on the piezoelectric substrate, has a plurality of electrode fingers and excites an acoustic wave; and a polycrystalline substrate which is provided on the side opposite from the surface of the piezoelectric substrate on which the pair of comb-shaped electrodes is provided, the polycrystalline substrate having an average particle size being equal to or less than 66 times an average pitch of the plurality of electrode fingers.SELECTED DRAWING: Figure 4 【課題】スプリアスを抑制すること。【解決手段】本発明は、圧電基板と、前記圧電基板上に設けられ、複数の電極指を有し弾性波を励振する一対の櫛型電極と、前記圧電基板の前記一対の櫛型電極が設けられた面と反対側に設けられ、平均粒径が前記複数の電極指の平均ピッチの６６倍以下である多結晶基板と、を備える弾性波共振器である。【選択図】図４