| 主权项 |
1. A duplexer comprising:
a transmission SAW filter device configured to output, to a common terminal, an unbalanced transmission signal in a first frequency band that has been inputted from an unbalanced transmission terminal; a reception SAW filter device configured to output, in a balanced state to balanced first and second reception terminals, an unbalanced reception signal in a second frequency band inputted to the common terminal; and a piezoelectric substrate having one main surface on which the transmission SAW filter device and the reception SAW filter device are provided; wherein the reception SAW filter device includes:
a first filter channel spanning from the common terminal to the first balanced reception terminal; anda second filter channel spanning from the common terminal to the second balanced reception terminal; of the first and second filter channels, the one filter channel having lower attenuation characteristics in the unbalanced transmission signal band at the respective balanced first and second reception terminals, when the unbalanced transmission signal is inputted to the common terminal, is located farther from the unbalanced transmission terminal than the other filter channel; the transmission SAW filter device is located in one region of the one main surface sectioned off by an imaginary line that is perpendicular or substantially perpendicular to a pair of opposing sides of the piezoelectric substrate; the reception SAW filter device is located in another region of the one main surface sectioned off by the imaginary line; the common terminal is disposed near or adjacent to a position where one of the pair of opposing sides intersects with the imaginary line; the transmission terminal is disposed at the position of an end portion, of the one region, that is close to or adjacent to the other of the pair of opposing sides and far or spaced from the imaginary line; the one filter channel is disposed on the one of the opposing sides so that the reception terminal in the one filter channel is disposed in the position of an end portion, of the other region, that is close to or adjacent to the one of the pair of opposing sides and far or spaced from the imaginary line; and the other filter channel is disposed on the other of the opposing sides so that the reception terminal in the other filter channel is disposed in the position of an end portion, of the other region, that is close to or adjacent to the other of the pair of opposing sides and far or spaced from the imaginary line. |
