| In recent years, with the rapid development of mobile communications market, users can at any time anywhere more hope to enjoy high quality communication.For this reason,mobile operators started in the indoor, outdoor, underground and other mobile blind spot set repeater to satisfy the requirements of the user for call quality, it is natural for mobile communications repeater has begun to become a hot research.RF front-end is an important component of GSM digital fiber optic repeater, Its main function is the received RF signal filtering, amplification and frequency conversion processing. With the portable mobile communications devices and miniaturization requirements of the proposal, but also to the design of RF front-end low-power, low cost, small size, high-quality direction. The quality of the RF front-end design can directly determine the quality throughout the repeater.This paper introduces the application of mobile communications repeater system and development situation, and then the discussion among some basic theory of the RF circuit design. Then, from the basic concept of the receiver, in-depth analysis of the performance, an important indicator of high dynamic receiver and the critical designs of repeater that are low-noise amplifier design techniques, selected frequency module design techniques and power amplifier design techniques.Finally, the author describes the specific focus of the work:A digital fiber optic repeater GSM RF front-end system design plan; Describes the design departments of molecular circuits and PCB board layout and routing; frequency synthesizer which describes the principle of local oscillator;On this basis, focusing on design and implementation of RF circuits, including low noise amplifier, down conversion circuit, filter circuit and frequency synthesizer circuits. Finally, the test results are the characteristics of the RF module, described the testing process some of the problems, propose solutions to the problem. |
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