Acoustic wave filter with reduced bulk-wave scattering loss, ladder filter incorporating same and method

摘要

A method and apparatus for an acoustic wave filter (110) with reduced bulk-wave scattering loss and a ladder filter (30, 40) incorporating same. The method includes steps of providing an acoustic wave propagating substrate (111) and disposing a first reflector (112) on a first surface thereof. The method also includes disposing a first transducer (115) to a first side of the first reflector (112). The first transducer (115) is separated from the first reflector (112) by a first gap (118) having a first width (114) exceeding one-fourth of the acoustic wavelength. The method also includes disposing a second reflector (112') to a side of the first transducer (115) opposite the first reflector (112). The first (112) and second (112') reflectors each include a group of periodically disposed reflective elements (113, 113'). The second reflector (112') is separated from the first transducer (115) by a second gap (140) having a second width (139). The method also includes disposing a first waveguiding element (116) having a first breadth (117) within the first gap (118).