Patent ID: 7659795
Filing Date: 2010-02-09
Classification: H03H,H04B

Abstract:
1. A multiband switch type antenna duplexer in which signals of different first and second frequency bands, respectively, share a single antenna, wherein: a transmitting frequency band f a first receive filter corresponding to said first frequency band and a second receive filter corresponding to said second frequency band are provided, output terminals on the output side of said receive filters are connected in parallel to each other via a matching circuit and a phase shift circuit, thereby forming a third parallel connection point, and said third parallel connection point is used as an output terminal for reception, the input terminal of the receive filter corresponding to said first frequency band and the input terminal of the receive filter corresponding to said second frequency band are connected in parallel to each other, via a first switching element which becomes conductive at the time of the reception of the signals of said first frequency band and is released at the time of the reception of the signals of said second frequency band and via a second switching element which is connected to the ground at the time of the reception of the signals of said first frequency band and becomes conductive at the time of the reception of the signals of said second frequency band and a quarter wavelength phase shift circuit, respectively, thereby forming a first parallel connection point, a control terminal which controls both said first switching element and said second switching element is provided between said first switching element and said first receive filter corresponding to said first frequency band, said first parallel connection point is connected in parallel to a switching element for transmission, which is connected to a common input terminal on the transmission side corresponding to said first and second frequency bands, becomes conductive at the time of the transmission of the signals of said first or second frequency band, and is released at the time of the reception, via a switching element which is connected to the ground at the time of the transmission of the signals of said first or second frequency band and becomes conductive at the time of the reception and a quarter wavelength phase shift circuit, thereby forming a second parallel connection point, and said second parallel connection point is directly connected to an antenna terminal or connected to the antenna terminal via a low-frequency pass filter or a high-frequency pass filter.