Research And Design Of The RF Front-End Of Portable Spectrum Analyzer

The development of the wireless communications industry promote the innovation of spectrum measurement. Meeting the demonds of users for field testing accelerate the spread and application of economic portable spectrum analyzer, which characterized by lightweight body design, friendly user interface and strong endurance. The overall performance of economic portable spectrum analyzer is directly determined by the performance of RF front-end. In this thesis, a novel RF front-end operating at the frequency range of 9 kHz to 6.0 GHz is designed to be used by economic portable spectrum analyzer. The following aspects are included in this thesis:1. The technical requirements of RF front-end used in economic portable spectrum analyzer is determined. Technical characteristics and performance of the common economic spectrum analyzer are concluded based on the analysis of the development of economic spectrum analyzer, and specifications of RF front-end of portable spectrum analyzer are determined.2. The design scheme of the system and main circuits of RF front-end of spectrum analyzer are confirmed. The RF front-end with good performance is designed by zero-IF techniques for lower cost and circuit miniaturaiation. High performance VCOs are used for broadband local oscillator design in order to achieve miniaturization requirements. The design scheme of the local oscillator filter bands achieve the effect of harmonic suppression greater than 40 dBc. Problems of DC offset and image rejection in the process of quadrature demodulation are solved and the feasibility of solutions is verified by MATLAB software. In addition, eliminating spurs by I/Q data extracted from the hardware is realized in intermediate frequency processing scheme.3. The test of RF front-end is completed. The existing problems in hardware testing are analyzed and solutions are given based on the problem. The indicators of the RF front-end are fully achieved the expected requirements, which is shown in test results.A novel RF front-end used by economic portable spectrum analyzer is designed and completed in this thesis. The RF front-end can be used by common economic portable spectrum analyzer, which have low cost, good performance, and important value and significance on the research and design of portable spectrum analyzer at the present stage.