| 摘要 |
PROBLEM TO BE SOLVED: To switch the system of a dual mode radio device shared by a TDD system and an FDD system with a simple circuit without decreasing the power efficiency of a transmission circuit. SOLUTION: In a TDD system transmission, a transmission signal is outputted from the third terminal 26 of a circulator 20 to a first terminal 22. In a TDD system reception, a reception signal is outputted from the first terminal 22 of the circular 20 to a second terminal 24. In an FDD system transmission, the signal is outputted from the transmission/reception terminal 13 of the antenna sharing unit 10 to an antenna terminal 12. In an FDD system reception, the reception signal is outputted from the antenna terminal 12 of the antenna sharing unit 10 to a reception terminal 16. Thus, the operation of transmission/ reception can be switched by using the antenna sharing unit 10 and the circulator 20. Since the number of switches required for switching a communication system, the dual mode radio device can be realized with the simple circuit without decreasing the power efficiency of a transmission circuit 42.
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