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应用科学学报

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宽带无线接收机射频前端结构研究与设计

周建政1, 2 ， 王志功1 ，李莉2 ，王科平1   

  1. 1.东南大学 射频与光电集成电路研究所，江苏 南京 210096；

    2.合肥工业大学 计算机与信息学院，安徽 合肥 230009

  • 收稿日期:2007-04-09 修回日期:2007-12-05 出版日期:2008-03-31 发布日期:2008-03-31

RF Front-End Topology Design of Wideband Receivers

Zhou Jian-zheng1,2, Wang Zhi-gong1, Li Li2, Wang Ke-ping1   

  1. 1. Institute of RF- & OE-ICs, Southeast University, Nanjing 210096, China；
    2. School of Computer & Information, Hefei University of Technology, Hefei 230009，China
  • Received:2007-04-09 Revised:2007-12-05 Online:2008-03-31 Published:2008-03-31

被引次数

29

摘要： 论证了宽带无线接收机宜采用上边注入、固定中频的二次正交混频低中频结构。文中推导出单双正交与双双正交这两种二次正交混频结构中分别存在4种镜像抑制比及这4种镜像抑制比与其结构中的幅度失配ΔA或相位失配Δθ之间的定量关系。两种结构的性能比较表明,宽带无线接收机射频前端更适合采用单双正交结构。为提高系统的镜像抑制性能，射频前端在单双正交结构的基础上添加两个模块：射频滤波器与第二次混频之前的多相滤波器。最后，给出了整个射频前端系统的镜像抑制性能关系式，并给出一个设计实例(DRM接收机射频前端)。Matlab仿真结果表明本射频前端结构具有良好的镜像抑制性能(当-10°≤Δθ≤10°，-0.1≤ΔA≤0.1时，4个镜像抑制比IRR≥61.16dB)，结合低中频结构固有的便于高集成度，支持多通信标准，且可避免寄生低频噪声影响等特点，使之成为实现宽带无线接收机的理想结构之一。

关键词: 宽带接收机, 射频前端, 二次变频, 正交混频, 镜像抑制比

Abstract: A high-side injection, fixed intermediate frequency (IF), double-quadrature-downconversion and low-IF structure is proposed for wideband receivers. Four image rejection ratios (IRR), and relationship between IRRs and the amplitude errors ΔA or phase errors Δθ of two kinds of double quadrature receiver structures (single-double and double-double quadrature structures) are derived. Comparison of these two structures shows that single-double quadrature conversion is more suitable for wideband receivers. To improve IRRs of the system, two modules, RF filter and polyphase filter before the second downconersion, are added to the single-double quadrature structure. The quantitative IRRs performance of the total RF-end and a design example, DRM receiver RF-end, are given. Simulation results show that this RF-end structure has good IRR performance (when -10°≤Δθ≤10°，-0.1≤ΔA≤0.1, IRRs≥61.16dB). This is an ideal structure for wideband radio receivers, combining the inherent characteristics of a low-IF structure such as suitability for high integrality, ability of supporting multi-standard communication, and immunity to parasitical low frequency noise.

Key words: wideband receiver, RF front-end, dual-conversion, quadrature downconvert, image rejection ratio (IRR)