宽带双信道射频前端的设计与实现

发布时间：2018-07-21 19:48

【摘要】：随着无线通信的广泛应用,全球范围内对无线电频谱资源的需求都呈现增长趋势。为了更好的使用和管理无线电系统,我们需要对无线电信号的频率、功率等特性进行检测,对信号携带信息进行分析并且识别信号的来波方向。90年代初,美国最先提出软件定义无线电(SDR)的概念,当前普遍认为SDR覆盖的频带为0.8GHz 6GHz。本文针对SDR定义的频带范围设计了可用于监测接收系统的双信道射频前端电路。该射频前端的接收频率范围为30MHz 6GHz,系统采用超外差接收机结构,总共使用三级变频单元,将接收频率范围内的射频(RF)信号下变频到中心频率为160MHz的中频(IF)信号,信道带宽为40MHz。本文首先调研了国内外主要的监测设备厂商现有产品的性能,提出了本监测设备中射频前端的指标要求。通过常用接收机结构性能的对比,确定采用超外差的接收方案。根据当前模数转换器、频率源等模块的限制因素,确定了射频前端三级变频的总体设计方案。其次,根据总体设计方案,分析每一级变频电路中的镜像频率,杂散响应和互调干扰等因素,确定该级变频电路滤波器设计要求和其他器件的选型方案。在确定射频电路的链路设计方案后,对射频前端的增益,噪声系数等系统指标进行仿真验证。完成仿真验证之后,进行各个模块电路的设计,主要完成了预选滤波器和中频滤波器的分析和设计,以及混频电路设计。本文针对第一混频电路高中频方案中本振泄露的问题,提出了一种本振泄露信号抑制电路的设计方案,解决了高中频方案设计中滤波器对本振泄露信号抑制不足的问题。最后,对双信道射频前端电路进行功能调试,并且对增益、噪声系数、和系统线性度等指标进行测试。根据测试的结果分析存在的问题,提出改进的方案,电路功能基本满足预期的设计要求。
[Abstract]:With the wide application of wireless communication, the global demand for radio spectrum resources is increasing. In order to better use and manage the radio system, we need to detect the frequency and power characteristics of the radio signal, analyze the information carried by the signal and identify the direction of the signal in the early 1990s. The concept of software defined radio (SDR) was first put forward in the United States, and it is generally considered that the frequency band covered by SDR is 0.8GHz / 6GHz. In this paper, a dual channel RF front-end circuit is designed to monitor the receiving system for the band range defined by SDR. The receiving frequency range of the RF front-end is 30MHz and 6GHz. The system adopts the structure of superheterodyne receiver. In total, the radio frequency (RF) signal in the frequency range is converted down to the if signal with a central frequency of 160 MHz, and the channel bandwidth is 40 MHz. This paper first investigates the performance of the existing products of the main monitoring equipment manufacturers at home and abroad, and puts forward the requirements of the RF front end in the monitoring equipment. By comparing the structure and performance of common receivers, the receiving scheme of superheterodyne is determined. According to the limiting factors of current analog-to-digital converter and frequency source, the overall design scheme of three-stage frequency conversion for RF front-end is determined. Secondly, according to the overall design scheme, the image frequency, spurious response and intermodulation interference of each stage frequency conversion circuit are analyzed, and the design requirements of the filter and the selection scheme of other devices are determined. After the link design scheme of RF circuit is determined, the gain and noise coefficient of RF front-end are simulated and verified. After the simulation and verification, the design of each module circuit is carried out, mainly the analysis and design of pre-selected filter and if filter, as well as the design of mixing circuit. In order to solve the problem of local oscillator leakage in the high frequency scheme of the first mixed-frequency circuit, this paper presents a design scheme of the local oscillator leakage signal suppression circuit, which solves the problem that the filter can not suppress the local oscillator leakage signal in the design of the high-frequency scheme. Finally, the dual channel RF front-end circuit is debugged, and the gain, noise coefficient and linearity of the system are tested. According to the test results, the existing problems are analyzed, and the improved scheme is put forward. The circuit functions basically meet the expected design requirements.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN98

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