低中频接收机I/Q不平衡的数字估计和补偿  

Digital I/Q Imbalance Estimation and Compensation in Low-IF Receiver

作　　者：陈春[1] 周立学[1] 李春化[1] 

机构地区：[1]西安电子工程研究所,西安710100

出　　处：《火控雷达技术》2014年第4期69-73,77,共6页Fire Control Radar Technology

摘　　要：相对于传统的超外差式接收机,低中频接收机由于不需要镜像抑制滤波器、中频滤波器等片外大体积昂贵器件,因而系统设计可以更加灵活,体积更小,成本更低,集成度更高。低中频接收机采用I/Q下变频进行镜像分离,但模拟前端I/Q不平衡导致的镜像抑制不足问题却是其一大缺点。本文提出了一种利用测试信号数字估计和补偿I/Q不平衡的方法来提高镜像抑制能力。仿真结果表明,在幅度不平衡不大于10%和相位不平衡不大于10°时,经补偿后的镜像抑制比能够达到50d B以上。Compared with the traditional super-heterodyne receiver, the low-IF receiver is much more flexible in system design, smaller in size,lower in cost and more highly integrated since it does not need for some large size ex-pensive components which are difficult to be integrated on the chip such as image rejection filter and IF filter,and so on. The low –IF receiver adopts I/Q down-conversion to separate image, however, insufficient image rejec-tion caused by I/Q imbalance of the analog front-end becomes one of disadvantages. In order to enhance the abili-ty of image rejection, a technique based on test signal to realize the digital I/Q imbalance estimation and compensa-tion is presented. Simulation results show the image rejection ratio after compensation can be over 50dB under con-dition that amplitude imbalance is not more than 10% and phase imbalance is not more than 10 ° .

关 键 词：I/Q不平衡 低中频接收机 测试信号 I/Q不平衡补偿 

分 类 号：TN957.5[电子电信—信号与信息处理]