| 摘要 |
An active duplex filter unit (7) for a combined GPS-cellular hand-set comprises a GPS low noise amplifier unit (13) connecting a receive antenna to the input of a GPS unit. It comprises a capacitance (15) and an inductance (16) preceding, in parallel, an amplifier (14) whose output is connected to ground via, in series, an inductance (17) and a capacitance (18) with a tap (19) for the application of a bias voltage (+V) between them. A similar cellular low noise amplifier unit (12) connects the receive antenna with the recive input of a cellular unit a transmit output of which is connected to a transmit antenna via a power amplifier. The GPS low noise amplifier unit (13) provides high gain and low noise figure at the GPS frequency and strong suppression in particular of frequencies used by cellular systems. The transmitter leakage signal in the GPS and cellular receivers is attenuated by the separation of the receive and transmit antennas. The GPS-cellular hand-set is compact and has low power consumption.
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