一种I/Q失衡误差的估计和补偿方法  

A Method of I/Q Imbalance Estimation and Compensation

作　　者：孟婕 王厚军[1] 叶芃[1] 杨扩军[1] 赵禹 郭连平[1] 蒋俊[1] MENG Jie;WANG Houjun;YE Peng;YANG Kuojun;ZHAO Yu;GUO Lianping;JIANG Jun(School of Automation Engineering,University of Electronic Science and Technology of China,Chengdu 611731)

机构地区：[1]电子科技大学自动化工程学院,成都611731

出　　处：《电子科技大学学报》2022年第2期227-233,共7页Journal of University of Electronic Science and Technology of China

基　　金：国家自然科学基金(61871100,61801092);中央高校基本科研基金(ZYGX2020ZB003,ZYGX2020ZB002,ZYGX2020J012);四川省重大科学仪器设备专项(2019ZDZX0041,2019ZDZX0037)。

摘　　要：零中频架构近年来得到广泛应用,但是该架构中的同相/正交(I/Q)失衡问题严重影响接收信号的质量。通过后端补偿算法消除I/Q失衡是最为有效的手段之一,然而现有文献对宽带系统I/Q失衡中时间失配(TM)误差的研究不够全面。该文建立了一种包含TM误差的宽带I/Q失衡增广误差模型,首先基于数据辅助型方法对失衡误差进行估计,采用多项式拟合的方法将相位失衡误差进行分解,基于分解后的失衡误差设计了一种基于非线性相位的实数有限脉冲响应(FIR)滤波器的补偿结构对各项失衡误差进行补偿。根据最小二乘(LS)的思想选择最优的延时值以保证补偿滤波器的因果性,补偿滤波器的设计结合Krylov子空间迭代算法中的共轭梯度平方(CGS)算法和增大过渡带设计频点间隔的设计思想。实验结果表明,设计的补偿滤波器在保证过渡带衰减特性的前提下提高了失衡误差的补偿精度,带有I/Q失衡增广误差的系统在引入该文设计的补偿结构后获得了近77 dB相对镜像比(RIR)提升。The zero-IF architecture has been widely used in recent years,but inphase/quadrature(I/Q)imbalance deteriorates the quality of received signals seriously.Eliminating I/Q imbalance through back-end compensation algorithms is one of the most efficient methods,but the existing literature does not comprehensively study the time mismatch(TM)error in broadband I/Q imbalance.An augmented error model of wideband I/Q imbalance including TM errors is established in this paper.The data-aided method is used to estimate the imbalance value in this paper,and then the polynomial fitting is applied to decompose the phase mismatch.Based on the decomposed error,a corresponding compensation structure based on a real-valued finite impulse response(FIR)filter with nonlinear phase is proposed to eliminate the separated imbalance errors.The design of the compensation filter firstly selects the optimal delay value according to the theory of least square(LS)to ensure the causality,and then utilizes the conjugate gradient square(CGS)algorithm based on the Krylov subspace,incorporating the design idea of increasing the transition band frequency interval to design the compensation filter.The experimental results show that the designed compensation filter improves the compensation accuracy of the imbalance error under the premise of ensuring the attenuation characteristics of the transition band,and the system with I/Q augmented imbalance can obtain a nearly 77 dB relative image ratio(RIR)improvement after introducing the compensation structure designed in this paper.

关 键 词：滤波器设计 I/Q失衡 KRYLOV子空间 多项式拟合 宽带零中频架构 

分 类 号：TN98[电子电信—信息与通信工程]