Patent ID: 7800460

Claim:
A balanced elastic wave filter device having an unbalanced terminal and first and second balanced terminals, comprising: a first elastic wave filter unit including first to third IDTs arranged in this order in an elastic wave propagation direction, the second IDT being divided into three portions in the elastic wave propagation direction so as to include first to third sub-IDT portions; and a second elastic wave filter unit including fourth to sixth IDTs arranged in this order in an elastic wave propagation direction, the fifth IDT being divided into three portions in the elastic wave propagation direction so as to include first to third sub-IDT portions; wherein one end of the first IDT, one end of the third IDT, one end of the fourth IDT, and one end of the sixth IDT are connected to the unbalanced terminal; the first to third IDTs and the fourth to sixth IDTs are arranged such that a phase of a signal transmitted from the unbalanced terminal to the first balanced terminal is different from a phase of a signal transmitted from the unbalanced terminal to the second balanced terminal by about 180 degrees; the second IDT includes a first common bus bar that commonly connects one end of each of the first to third sub-IDT portions together, the other end of the second sub-IDT portion is connected to the first balanced terminal, the other end of the first sub-IDT portion and the other end of the third sub-IDT portion are connected to a ground terminal; and the fifth IDT includes a second common bus bar that commonly connects one end of each of the first to third sub-IDT portions together, the other end of the second sub-IDT portion is connected to the second balanced terminal, and the other end of the first sub-IDT portion and the other end of the third sub-IDT portion are connected to a ground terminal.