应用于数字广播的镜像抑制混频器的设计  

Design of image rejection mixer for digital broadcast

作　　者：黄晶[1] 王志功[1] 徐建[1] 吴毅强[1] 

机构地区：[1]东南大学射频与光电集成电路研究所,江苏南京210096

出　　处：《中国集成电路》2013年第4期22-26,共5页China lntegrated Circuit

摘　　要：在二次变频低中频结构的DRM/DAB数字广播射频极宽频带(148.5kH～1492MHz)接收机中,为了实现良好的镜像抑制性能,第二次变频采用双正交混频器结构。与单正交结构相比较,双正交型混频器具有更优的镜像抑制性能以及更高的成品率。考虑到宽带以及系统输出信号的信噪比,本文中采用了结合多级多相滤波器的双正交下变频有源混频器,在满足镜像抑制要求的的同时提供一定的增益。经理论分析和实际仿真结果表明,该结构的混频器具有良好的镜像抑制性能,镜像抑制比在DRM模式下IIR>48dB,DAB模式下IIR>55dB,而且对正交信号幅度和相位的失配不敏感,能够满足数字广播接收机射频前端的所需指标要求。目前整个芯片正在测试中,最终芯片将在Himalaya公司的接收机上进行整机验证。A dual-conversion low-IF architecture is proposedin the digital broadcasting receiver of a very wide band radio frequency （148.5kHz-1492MHz）,and double orthogonal mixer is used in order to achieve agood imagerejection.Compared with single orthogonal structure, double orthogonal mixer has a betterimagerejection and higher yield.Considering the broadband and the signal-to-noise ratioof system output signal,this paper usesactive mixer in double orthogonal down-conversion combined with muhistage poly-phase filter to meet the requirements of the imagerejectionand provide appropriate gain.The theoretical analysis and practical simulation results show that the structure of mixer has a goodimagerejection performance,image reject rate of DRM is about 48dB and image reject rate of DAB is about 55dB.And theimage reject rateis not sensitiveto the amplitude and phase mismatch of orthogonal signal, meeting the design requirements of digital broadcasting receiver.At present the chip is being tested and the chip will be Finally verified in the receiver of Himalaya company.

关 键 词：镜像抑制 双正交 低中频 多相滤波器 

分 类 号：TN773[电子电信—电路与系统]