Patent ID: 7283016

Claim:
A balanced acoustic wave filter including an unbalanced terminal and first and second balanced terminals, the filter comprising: an acoustic wave substrate; a first longitudinally-coupled filter element disposed on the acoustic wave substrate and including at least three IDTs connected between the unbalanced terminal and the first balanced terminal; a second longitudinally-coupled filter element disposed on the acoustic wave substrate and including at least three IDTs connected between the unbalanced terminal and the second balanced terminal through which a signal of an opposite phase to that in the first balanced terminal of the first filter element flows; a first connecting line connecting a grounded end of the IDT connected to the first balanced terminal of the first filter element to a grounded end of the IDT connected to the second balanced terminal of the second filter element so as to define a common midpoint grounded portion and provided on the acoustic wave substrate; and a second connecting line connecting grounded ends of the IDTS connected to the unbalanced terminal in the first filter element to grounded ends of the IDTs connected to the unbalanced terminal in the second filter element so as to define an unbalanced-side grounded portion and provided on the acoustic wave substrate; wherein the common midpoint grounded portion and the unbalanced-side grounded portion are electrically separated from each other on the acoustic wave substrate.