Research On The 900MHz Low Power Indoor Repeater

In this article,the author tries to interpret the design theory, thoughts, methods and measurement of the key modules in a narrowband repeat system. The author also gives the detail regard in the design and measurement course.The author explains the importance of a repeater in the mobile communication, and describes its principles, classification, correlative concepts, the differences between a base station, the status of development, market and research. The author also introduces the contents discussed in the article. Basic theories and concepts of microwave circuits, including the s parameter, the design of LNA, the noise and the nonlinear distortion are summarized. Discuss the design course of a wideband repeater system from the system design to the implement of circuits and the measurement, including the decision of system parameter, the system structure and components. Propose mixing-filtering method to improve the selectivity of repeater. The mixing-filtering module is the key module of a narrowband repeater. The author interprets its importance and principle and introduces the SAW filter and mixer, especially the diode double balanced mixer. Discuss the PLL frequency synthesizer which produces the local oscillator for the system. The author summarizes the frequency synthesize techniques, introduces the application of MC145152 and gives a detail discusses on the parameters of PLL. At last the author summarizes his work in this project and his experience gained in this project. The circuits' schematics and the PCB layouts are presented in the appendix.