| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a front-end module for triple-band portable telephone, which can simplify the constitution of a portable telephone and can reduce the size of the telephone. SOLUTION: This front-end module is provided with a branching filter circuit 8, connected to an antenna 7 and composed of a plurality of notching circuits 19 and 20, antenna switches 9 and 12 which connect transmitting circuits and receiving circuits with respect to their corresponding notching circuits 19 and 20 by switching, and filters 10 and 11, which remove higher harmonics. One circuit 20 of the notch circuits 19 and 20 is used for two communications systems which use adjacent frequency bands. The antenna switch 12 connected to the notching circuit 20 is also used for the transmitting circuits used for the two communication systems. The module is also provided with SAW filters 15 and 17 or SAW duplexers which separate the received signals of the two communication systems from each other.</p> |
