| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of disturbance to a communication apparatus of an adjacent sub network by suppressing variation in impedance when switching transmission/reception of the communication apparatus while achieving downsizing by disposing a band pass filter at a receiving circuit section side. SOLUTION: A receiving amplifier element 6 is disposed on an initial stage of a receiving circuit section and a circuit on a post-stage of the receiving circuit section is electrically disconnected from the outside. In a transmitting circuit section, a first switch element 3 is inserted serially between a transmitting amplifier element 4 and an impedance element 2 and in the case of transmission, the impedance element 2 becomes output impedance of a communication apparatus 1. Further, as a circuit configuration, a second switch element 5 is inserted between a terminal at a side of the transmitting amplifier element 4 of the impedance element 2 and a ground, and in the case of reception, the same impedance element 2 also becomes input impedance of the communication apparatus 1. Thus, impedance can be fixed at all the time without depending on a transmitting/receiving state. COPYRIGHT: (C)2011,JPO&INPIT
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