Patent ID: 8125297

Claim:
A filter comprising: a first filter unit; a second filter unit; and a balun, wherein the first filter unit includes: a plurality of series resonators connected in series to each other between a first input terminal and a first output terminal; a plurality of parallel resonators each having one end connected to a node associated with at least one of the plurality of series resonators between the first input terminal and the first output terminal; and a common inductance having one end connected to the other ends of at least two of the plurality of parallel resonators and the other end connected to a ground terminal, the second filter unit includes: a plurality of series resonators connected in series to each other between a second input terminal and a second output terminal; a plurality of parallel resonators each having one end connected to a node associated with at least one of the plurality of series resonators between the second input terminal and the second output terminal; and a common inductance having one end connected to the other ends of at least two of the plurality of parallel resonators and the other end connected to the ground terminal, and the balun divides an input signal into two signals having opposite phases and outputs the two signals to the first input terminal and the second input terminal.