PIEZOELECTRIC THIN FILM RESONATOR, FILTER, COMMUNICATION MODULE AND COMMUNICATION DEVICE

摘要

PURPOSE: A piezoelectric thin film resonator, a filter, a communication module, and a communication device are provided to suppress the ripple in a communication band by preventing the generation of a stand wave. CONSTITUTION: A bottom electrode(3) is formed on a substrate(1). A piezoelectric-film(4) is formed on the bottom electrode. The top electrode is formed on the piezoelectric-film to face with the bottom electrode. At least a part of the peripheral part of the top electrode has a reverse tapered shape. At least a part of the peripheral part of the top electrode corresponds to the peripheral part of piezoelectric-film. The peripheral part of the top electrode is arranged near the peripheral part of the piezoelectric-film.