目标模拟器X波段宽带射频前端的设计

发布时间：2018-03-22 06:01

本文选题：目标模拟器　切入点：射频前端　出处：《南京航空航天大学》2014年硕士论文　论文类型：学位论文

【摘要】：目标模拟器是雷达射频仿真系统中的关键部件之一,而射频前端对目标模拟器的性能有直接影响,因此深入研究雷达目标模拟器射频前端具有非常重要的现实意义。本文研究了具有高杂散抑制能力的目标模拟器X波段宽带射频前端,其主要功能是把X波段的载波频率变换到低中频。该宽带射频前端的低中频为50MHz~550MHz,相对带宽达到了166.7%,在此条件下要实现高杂散抑制具有很高的技术难度。本文首先通过研究各种射频接收技术,采用了超外差二次下变频接收方法,并对下变频过程中产生的组合频率分量进行了分析,然后确定了宽带射频前端的技术指标,对宽带射频前端中的各部件进行了指标优化,利用ADS、HFSS等仿真软件设计、仿真了带通滤波器、低噪声放大器、混频器、中频带通滤波器以及功率放大器等部件,并完成了实物加工与测试。为实现高杂散抑制,本文通过增加传输零点的方式,改善滤波器的选择性,提高宽带射频前端的带外杂散抑制能力;采用双平衡混频器,抑制与通带重叠的组合频率分量,提高宽带射频前端的带内杂散抑制能力。本文还针对自动增益控制电路、本振单元等进行了设计与分析。系统测试结果表明,该宽带射频前端的带内杂散抑制达到了40dB以上,带内增益平坦度基本小于±2d B,基本满足了目标模拟器对宽带射频前端的技术要求。
[Abstract]:The target simulator is one of the key components in the radar RF simulation system, and the RF front-end has a direct impact on the performance of the target simulator. Therefore, it is very important to study the RF front-end of radar target simulator. In this paper, the X-band wideband RF front-end of radar target simulator with high spurious suppression capability is studied. Its main function is to convert the carrier frequency of X band to the low intermediate frequency. The low intermediate frequency of the broadband RF front end is 50 MHz / 550MHz, and the relative bandwidth is 166.7%. It is very difficult to realize the high spurious suppression under this condition. By studying various radio frequency receiving technologies, The superheterodyne secondary downconversion receiver is adopted, and the combined frequency components produced in the downconversion process are analyzed, then the technical indexes of the broadband RF front-end are determined, and the indexes of the components in the broadband RF front-end are optimized. The simulation software ADSHSS is used to simulate the components such as bandpass filter, low noise amplifier, mixer, medium band pass filter and power amplifier. In this paper, the selectivity of filter is improved by increasing the transmission zeros, and the out-of-band spurious suppression ability of broadband RF front-end is improved, and the combined frequency component overlapped with passband is suppressed by using double-balanced mixer. This paper also designs and analyzes the automatic gain control circuit and local oscillator unit. The system test results show that the in-band spurious suppression of the broadband RF front-end is above 40dB. The in-band gain flatness is less than 卤2dB, which basically meets the technical requirements of the target simulator for the broadband RF front-end.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN955

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