.2.4 G High-sensitivity Receiver Rf Front-end Design And Realization

Luggage positioning and tracking system is a short-range wireless position technology that is used for positioning and tracking luggage at airport to prevent them being damaged or lost. Receiver RF front-end is an important part of the system, which can receive and amplifier signal, filter interference, down-convert RF signal to IF or baseband signal and realize automatic gain control,etc. Then the satisfied signal is transmitted to digital part for further processing.The transmitter must be small enough with invisibility,that is to say,the emitting power is low. Only the receiver performs high sensitivity, high gain and wide dynamic range to ensure that weak signal is received for digital correlation peak detection,can the system achieve accurate position. In addition, the receiver shoud possess features of small size, low power consumption and low cost.In order to achieve the above target, in this paper, 2.4GHz high sensitivity receiver RF front-end is designed and implemented.Firstly, after the wireless environment of several international airports is tested, 2.4GHz band has been choosen. Zero-IF structure is preferred by analyzing and comparing different topological structures of receiver RF front-end. Then,appropriate chips are selected based on performance indicators of the system and zero-IF structure.Next, system-level simulation model is established by ADS software and parameters of the module are setted according to actual performances of selected chips to verify the feasibility of receiver RF front-end.Secondly, each function module is designed, including loop filter circuit of oscillator, impedance matching circuit of the two initial low noise amplifiers(LNAs), automatic gain control(AGC) circuit, LC low-pass filter and final amplifier circuit of baseband. At the end of ChapterⅢ, the schematic of receiver RF front-end is presented.Thirdly, final printed circuit board(PCB) layout is designed with scientific and rational component placing and transmission line routing. Then PCB files are emailed to the company specialized in manufacturing multilayer PCB to produce circuit board. After crafting chips, each function module must be debugged including testing phase noise of oscillator circuit, optimizing peripheral circuit of LNA1, improving the performance of LC low-pass filter,testing frequency response characteristic of baseband circuit. Then the system of receiver RF front-end is debugged when each module functions properly.Finally, all test results are recorded and analyzed after performance test.The results show that the designed receiver RF front-end fullfils the specification requirements.