| 摘要 |
PURPOSE: An RF transmitting apparatus of an RIU(Radio Interface Unit) in a WLL(Wireless Local Loop) system is provided to improve the signal/noise ratio of an RF transmitting apparatus so as to increase the isolation of the front end of the RF transmitting apparatus in a WLL terminal. CONSTITUTION: In order to reduce the output noise of a system to the minimum, an amplifier(210), of which the gain is larger than '1', is installed in the input port of a mixer(200) in the front end of a transmitting unit. Accordingly, the whole front end of the transmitting unit becomes an amplifier, not a modulator. In case that the amplifier(210), of which the gain is larger than '1', is installed in the input port of the mixer(200), a receiving band noise generated from a transmitting output port is reduced remarkably because a total noise factor is reduced.
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