The Design Of RF Front-end Based On Ultrashort Wave Anti-Jamming Communication System

The RF receiver is at the front end of the whole communication system.It plays an important role in the performance and structure of the entire communication system.As one of the most important equipments in the communication system,ultra short wave receiver is widely used in military communication system and civil communication system.Moreover,with the development of high performance integrated chip,it also promotes the development of high performance ultra short wave receiver,and makes it develop towards high linearity,high sensitivity and high integration direction.Therefore,it is of great practical significance to study the ultrashort wave RF receiver.On the basis of a large number of literatures on RF receiver design,firstly,the structure of the receiver is analyzed,and the structure and working principle of each receiver are analyzed.The advantages and disadvantages of different structures are compared,and the key technical indicators of the receiver are analyzed.From the point of view of system performance and integration,this paper proposes a superheterodyne secondary frequency conversion scheme based on this topic.It is mainly composed of LNA mixer and IF amplification and other circuit modules.Secondly,through the system simulation,the main scheme of the receiver and the key technical indexes such as gain distribution,noise figure and frequency selectivity are analyzed and demonstrated.According to the requirements of technical indicators LNA module,mixer and IF amplification module,the frequency source module circuit were designed,and the modules were tested separately.Therefore the 225-512 MHz signal is filtered,mixed,amplified,and the center frequency of 72 MHz IF signal is output.Among them,the entire design process using an intermediate frequency of 800 MHz high frequency,IF2 using low frequency,the purpose is to keep the signal from the useful signal,and to improve the overall system image rejection ratio.Finally,on the basis of the design of each independent module,the performance of each module is integrated to complete the design of RF front-end system.The output of the whole system is tested,so as to realize the signal amplification,filtering and mixing and output of the required IF signal in the whole system.