Design And Development Of LNA/diplexer Module Base On RP Repeater Transceiver Front-end

With the rapid development of microwave communication, technical means has been continuously improved. For the demand of communications equipment integrated, systematic and miniaturization demand is higher and higher. The LNA/diplexer module is an essential part of microwave communications repeaters system and micro base station system for the market requirement. It enjoys such merits:narrow bandwidth, low noise figure and high gain, low insertion loss, high attenuation, miniaturization, integration, and high production repeatability features. It is used to share the same antenna system for both uplink and downlink signal which has perfect isolation. The low noise of the system is greatly improved the sensitivity of the receiving system. The appropriate amplification of the useful signal is helpful for consequent noise suppression and to maintain a high linearity. LNA unit and duplexer unit are integrated to form a module, which is relative to the independent device it has better range of applications and more cost-effective.The main work of this thesis is as follows:1、The basic principle of LNA/diplexer are summarized at first, then outline the development of low noise amplifiers and filters and research, as well as the purpose and significance of this study.2、In the section of low noise amplifier design, it analyzes and summarizes the design process. Based on the ADS simulation software, the L-band low noise amplifier is designed. The paper innovatively proposes a negative feedback at source and paralleling impedance at gate method, which realizes full band stability. It gives a detailed design process and design results. In addition the other two common design schemes of the common low-noise amplifier are given.3、In the diplexer design aspects, firstly, it introduces and outlines the coaxial cavity filter design theory and the design process. Then the actual simulation is carried out on the receive filter design, we adopt a multi-software co-simulation design. The filter structure is determined by the filter design software. By using AWR software lumped circuit model is simulated to optimize the whole coupling coefficient. Then3D electromagnetism software HFSS is used for simulation of resonant frequency of diplexer receive filter, coupling coefficients of each two resonators, and external quality factor. Easily to make sure the resonance unit and the diplexer physical structure and dimension form above these steps.4, We make two integral units, respectively, debug, then assemble and install them, make overall test. The actual test indicators meet the design specifications demand.Base on the design theory of the LNA and the coaxial cavity filter, this thesis is aim to design a LNA/diplexer module used in a RP repeater system. The module has been successfully applied in a microwave radio communication system. The products have a good market, meanwhile two design methods and steps of the units in this paper has a certain significance in microwave device design industry personnel.