LADDER-TYPE THIN-FILM BULK ACOUSTIC WAVE FILTER

摘要

A ladder filter comprising a plurality of bulk acoustic wave resonators, the resonators comprising a plurality of series resonators in series between an input terminal and an output terminal of the filter, and one or more shunt resonators e ach connected between a junction between two series resonators and a common terminal, the series resonators comprising an input series resonator connected to the input terminal and an output series resonator connected to the output terminal , and wherein the shunt resonators are designed to satisfy:a unity aspect ratio and wherein the series resonators are designed to satisfy an aspect ratio different from unity.The aspect ratio is defined as the ratio of length to width of the resonator.