Patent ID: 8330553

Claim:
A duplexer, comprising: an acoustic wave element having a first terminal and a second terminal; a substrate mounting the acoustic wave element on a surface; a first columnar conductor electrically connected to the first terminal, and drawn to a back surface of the substrate, while being buried partially in the substrate; a second columnar conductor electrically connected to the second terminal, and drawn to the back surface of the substrate, while being buried partially in the substrate; a first ground pattern region arranged between the first columnar conductor drawn part and the second columnar conductor drawn part, on the back surface of the substrate; a second ground pattern region electrically connected to the first ground pattern region and arranged in the part not including between the first columnar conductor drawn part and the second columnar conductor drawn part, on the back surface of the substrate; and a third columnar conductor electrically connected to the first ground pattern region, while being buried partially in the substrate, wherein the acoustic wave element includes a third terminal, a fourth columnar conductor is electrically connected to the third terminal, and drawn to the back surface of the substrate, while being buried partially in the substrate, and the second terminal is a first balanced output terminal, the third terminal is a second balanced output terminal, and the second columnar conductor drawn part and the fourth columnar conductor drawn part are arranged on the same side in the substrate.