Design And Implementation Of RF Front-end Components In A Compact Spectrum Monitoring Equipment

With the rapid development of communications,the carrier frequency of communication device become higher and higher.The number of communication equipment is also rapidly growing.Leading to an increasingly scarce of spectrum resources.Spectrum congestion and illegal occupation of the band becoming a major factor affecting the wireless communications.The spectrum allocation and administrative monitoring have been made necessary in areas of communications, military,navigation,radio and television,etc.As a major equipment in RF area,spectrum monitoring equipment plays an extremely important role.According to the project requirements, the thesis has designed a miniaturization, low power consumption, high sensitivity spectrum monitoring equipment.As a high performance spectrum monitoring equipment,its frequency measurement range is 9kHz~8GHz,and the Real-time analysis bandwidth is 10 MHz.It not only used to spectrum monitoring but also has the function of the analysis of digital modulation signal.This device uses a superheterodyne architecture,abandons the previous filter bank and the YTF scheme.Using high-IF-frequency scheme,the system’s first-IF is 9.864 GHz.After a upconversion and twice downconversion,the RF signal is converted to 64 MHz IF-signal.We use IF-Filter and signal conditioning unit to ensure the device’s high sensitivity and large dynamic range.First,the thesis pointed out the design indexes,and analysed the key index such as NF,sensitivty,P1 dB,spurious response and residual response.The thesis pointed out the effect to the system caused by the indexes.Second, the thesis design the system of spectrum monitor equipment’s RF front-end, including the choose of the system architecture,the design of frequency conversion,spurious analysis,link gain distribution and noise analysis. With the help of ADS,putforward a feasible scheme for the system.Third,decomposed the system to modues,including cotrolled attenuator,LNA,three times frequency conversion unit.The frequency conversion unit is composed of anti-image filter,Mixer,IF filter,IF signal conditioning circuit.The filter scheme adopt the solution of microstrip filter,SAW and LC filter technology.The IF signal conditioning circuit adopt the solution of low power consumption.Finally,united the circuits together to complete the system integration work.Tested the indicators of the system and analyzed the results.