Patent ID: 7880562

Claim:
A balanced-output triplexer comprising: an input terminal for inputting a first unbalanced signal of a first frequency band, a second unbalanced signal of a second frequency band higher than the first frequency band, and a third unbalanced signal of a third frequency band higher than the second frequency band; a pair of first balanced output terminals for outputting a first balanced signal corresponding to the first unbalanced signal; a pair of second balanced output terminals for outputting a second balanced signal corresponding to the second unbalanced signal; a pair of third balanced output terminals for outputting a third balanced signal corresponding to the third unbalanced signal; a first filter provided between the input terminal and the pair of first balanced output terminals, for passing signals having frequencies within the first frequency band selectively, and for converting the first unbalanced signal into the first balanced signal and outputting the first balanced signal to the pair of first balanced output terminals; a second filter provided between the input terminal and the pair of second balanced output terminals, for passing signals having frequencies within the second frequency band selectively, and for converting the second unbalanced signal into the second balanced signal and outputting the second balanced signal to the pair of second balanced output terminals; and a third filter provided between the input terminal and the pair of third balanced output terminals, for passing signals having frequencies within the third frequency band selectively, and for converting the third unbalanced signal into the third balanced signal and outputting the third balanced signal to the pair of third balanced output terminals, wherein: each of the first to third filters includes a pair of output resonators that are electromagnetically coupled to each other and connected to the corresponding pair of balanced output terminals, the pair of output resonators consisting of a first output resonator and a second output resonator, each of the first and second output resonators having an open end and a short-circuited end, the first and second output resonators being opposite in positional relationship between the open end and the short-circuited end; and the first and second output resonators are opposed to each other such that the open end of the first output resonator and the short-circuited end of the second output resonator are close to each other while the short-circuited end of the first output resonator and the open end of the second output resonator are close to each other.