Optimal Design Of X-band Low Noise Amplifier

Low noise amplifier is one of the important parts in the microwave receiving system,and located in the front end of the receiving system. The main function of LNA is to amplify the received signal and restrain the noise. It’s performance will directly decide the quality of the whole receiving system’s sensitivity and noise performance. With the rapid development of the satellite communications, radar, navigation technology, people pay more and more attentions to the research and design of the better performance and skillful LNA. The main contents are as follows:Firstly, this paper make a general introduction through the research background,significance and the status of LNA. And then this paper make a detail summary about the theory of the micro-strip theory which are used in the thesis. We get the character of micro-strip line and the calculation of parameters by the brief introduction of microwave transmission line. We analyze the design of the matching circuit with micro-strip line structure.Secondly, The microwave network is briefly introduced in this paper, explaining the concepts of the two-port network, S-parameters and Smith chart. And then this paper introduce the performance index involved in the LNA design, Mainly through the detailed analysis and elaboration of the concept and significance of noise, stability, gain, VSWR.Finally, this paper combine with bias circuit and the stability of LNA, with source series negative feedback and RF design tool ADS 2013, the LNA which configures series of two stages cascaded transistors VMMK-1218 from AVAGO company, and the matching circuits is design with micro-strip line. By means of the simulation, the LNA exhibits operating with 8.7~9.3GHz, noise figure less than 0.2d B, gain more than 26 d B, all the two VSWR less than 1.4, and has a good performance, meets the needs of the design index.