Design Of RF Front-end Of Microwave Real-time Spectrum Analyzer

From the beginning of the twentieth century, the innovations of RF technology has continued to emerge.Entered the twenty-first century, with the development of software radio technology, RF technology has also made the breakthrough and it’s application got deeply into society. The space is full of the RF signal, and RF interference issues between different systems also increases. How to detect and assess the interference signal effectively has been a big problem troubled engineers. As a general electronic test equipment, microwave spectrum analyzer is the most effective tool to detect signal and measure spectrum, and also one of the necessary tools on the research, production, detect and maintain of electronic equipment. And It is widely used in radio management and the military and civilian radio communications.This thesis research technology of microwave spectrum analyzers RF front-end design. For the domestic market, the measure range of microwave real-time spectrum analyzer is too low. So it is unable to conduct monitoring and management in X band and higher frequencies and is unable to meet the status of wireless communications, radar, space communications and other military systems testing requirements under the new system. Based on the technology of broadband and high-sensitivity receiver, this thesis designed a microwave spectrum analyzer front-end component whose measurement ranges 10MHz~20GHz and analyze bandwidth up to 70 MHz. According to the design requirements and complete index system of the analyzer, the superheterodyne structure was choosed, and writer use low band up converter and high band low converter in project design. On high frequency band, the design abandoned scheme of using YTF which is commonly used internationally, and choosed the switch filter group, avoiding the hysteresis, temperature drift,band group delay wave and other non-linear characteristics of using YIG. On high frequency band, a third harmonic mixing scheme was choosed and designed multiplier filter module to solve the problem that LO coverage does not reach the design demand.Firstly, thesis introduced several common structures of microwave real-time spectrum analyzer front-end, and the key indicators of the noise factor, sensitivity, dynamic range, etc. are described. The writer proposed the indicators of the microwave real-time spectrum analyzer front-end, and identified the scheme of frequency conversion, and doing the front-end system-level design, including the frequency conversion scheme research, analyzes spurious response, filter indicators, and the distribution of the noise figure.Then the entire front-end is divided into several modules. The main modules the writer research are the first, second and third mixing modules, multiplier filter module and filter module. These modules are simulated by using ADS software, and gives the results of physical.Finally, the writer tested the entire front-end of the microwave spectrum analyzer with a standard test scheme, and analyzed the results.