接收机下变频器级联噪声系数研究  

Study on cascade noise figure of receivers with down converter

作　　者：张广显 Zhang Guangxian(The 13th Research Institute,CETC,Shijiazhuang 050051,China)

机构地区：[1]中国电子科技集团公司第十三研究所,河北石家庄050051

出　　处：《电子技术应用》2021年第1期7-10,共4页Application of Electronic Technique

摘　　要：依据噪声系数定义,推导出了包含混频器接收机的级联噪声系数公式,根据公式很容易计算和分析器件噪声、增益及镜频抑制度对整机噪声系数的影响。镜频抑制滤波器位置要在低噪声放大器后尽量靠近混频器,滤波器前的增益以及滤波器镜频抑制度要足够大,至少大于20 dB。通过合理的结构设计以及镜频抑制后,二次、三次下变频接收机噪声系数分别比镜频噪声完全不抑制时降低接近6 dB、9 dB。According to the definition of noise figure,this paper deduces the cascade noise figure formula of receivers with mixers.By using this formula,it is easy to calculate and analysis the system noise figure affected by the device noise figure,gain and filter image rejection.The position of image rejection filter behind the low noise amplifier needs place as close as to the mixer.The gain before the filter and filter image rejection needs high enough,at least greater than 20 dB.Through the proper design and image rejection,the noise figure of the receiver which has two-stages,three-stages frequency conversion will decrease close to 6 dB and 9 dB,than when the image noise do not be rejected at all.

关 键 词：接收机 级联 噪声系数 混频器 镜像抑制 

分 类 号：TN85[电子电信—信息与通信工程]