复旦大学：《集成电路工程》教学资源（硕士士学位论文）射频接收机中的自动增益控制.pdf

I 目录图目录 ··························································································· III 表目录 ··························································································· V 摘要 ····························································································· VI Abstract ······················································································ VII 第一章概述 ···················································································· 1 1.1 研究背景············································································· 1 1.2 研究动机············································································· 2 1.3 论文结构············································································· 3 第二章射频设计中的主要参量与接收机架构 ·········································· 4 2.1 非线性················································································ 4 2.1.1 三阶交调点 ································································· 5 2.1.2 IP3的级联公式 ····························································· 7 2.1.3 宽带信号的三阶交调 ····················································· 8 2.1.4 复合三阶失真 ······························································ 9 2.2 噪声·················································································· 12 2.2.1 信噪比 ······································································ 12 2.2.2 噪声系数 ··································································· 13 2.3 信号噪声失真比 ··································································· 14 2.3.1 概述 ········································································· 14 2.3.2 信号噪声失真比的级联公式 ··········································· 15 2.3.3 影响信号噪声失真比的几个因素 ····································· 16 2.3.3.1 噪声系数对信号噪声失真比的影响 ···················· 17 2.3.3.2 非线性对信号噪声失真比的影响 ······················· 17 2.3.3.3 增益对信号噪声失真比的影响 ·························· 18 2.4 接收机的主要架构 ································································ 22 2.4.1 外差架构 ··································································· 22 2.4.2 零中频架构 ································································ 24 2.4.3 其他架构 ··································································· 25 第三章系统自动增益控制 ································································· 26 3.1 概述·················································································· 26 3.1.1 反馈环路与前馈环路 ···················································· 26

II 3.1.2 数字自动增益控制 ······················································· 28 3.2 数字电视调谐器(TV-tuner)系统架构及系统控制方法 ···················· 29 3.2.1 数字电视调谐器(TV-tuner)的系统架构 ······························ 30 3.2.2 各模块增益控制流程 ···················································· 30 3.2.3 各个模块的目标功率设计 ·············································· 33 3.3 自动增益控制算法 ································································ 33 3.3.1 系统控制状态机 ·························································· 34 3.3.2 增益核心算法状态机 ···················································· 35 3.3.3 输出功率的数字编码方法 ·············································· 38 3.3.3.1 功率检测器(PWD)的输出编码 ·························· 39 3.3.3.2 幅度检测器(RSSI)的输出编码 ·························· 40 3.4 其他模块············································································ 41 3.4.1 RC 偏差校正模块 ························································· 41 3.4.2 功率检测器的直流失调校正 ··········································· 42 3.4.3 脉宽调制译码 ····························································· 43 3.4.4 噪声与带外非线性的优化模块 ········································ 45 第四章电路仿真及测试 ···································································· 49 4.1 各模块仿真结果 ··································································· 49 4.1.1 系统仿真 ··································································· 49 4.1.2 电阻电容校正模块仿真 ················································· 51 4.1.3 功率检测器直流校正模块仿真 ········································ 51 4.1.4 脉宽调制译码模块仿真 ················································· 51 4.2 数字电视调谐器的测试结果 ···················································· 52 4.2.1 系统自动增益控制测试 ················································· 52 4.2.2 脉宽调制译码测试 ······················································· 53 第五章总结与展望 ·········································································· 54 5.1 总结·················································································· 54 5.2 展望·················································································· 54 参考文献 ······················································································· 55 致谢 ······················································································· 57

III 图目录图 1-1 1995 到 2012 年全球无线通信用户数量估计 ....................................... 1 图 1-2 接收机的一般架构 ............................................................................... 2 图 1-3 线性度与噪声之间的折衷 .................................................................... 2 图 2-1 三阶交调量对有用信号的影响 ............................................................. 5 图 2-2 带内三阶交调量的干扰 ........................................................................ 5 图 2-3 三阶交调点在对数坐标上的表示.......................................................... 6 图 2-4 多级级联的 IP3 .................................................................................... 7 图 2-5 一个频点三阶交调量的两种产生方式 .................................................. 8 图 2-6 互交调与复合三阶交调产生差拍数对比 ............................................. 10 图 2-7 宽带信号的复合三阶差拍分布 ........................................................... 11 图 2-8 LNA 二端口噪声等效电路.................................................................. 13 图 2-9 不同输入下的信号噪声失真比 ........................................................... 15 图 2-10 噪声系数对信号噪声失真比的影响 .................................................. 17 图 2-11 非线性对信号噪声失真比的影响 ...................................................... 18 图 2-12 可变增益模块输入与输出、增益的特性 ........................................... 19 图 2-13 级联下目标功率与后级最优输入点的关系 ....................................... 20 图 2-14 级联情况下后级信号噪声失真比与输入的关系 ................................ 21 图 2-15 外差架构下信号传输过程 ................................................................ 23 图 2-16 外差接收机的基本架构 .................................................................... 23 图 2-17 双中频外差接收机架构 .................................................................... 24 图 2-18 零中频接收机架构 ........................................................................... 24 图 3-1 反馈自动增益控制环路 ...................................................................... 26 图 3-2 前馈自动增益控制环路 ...................................................................... 27 图 3-3 数字编码的混合自动增益控制环路 .................................................... 28 图 3-4 全球通信标准分布 ............................................................................. 29 图 3-5 基于多标准的数字电视调谐器架构 .................................................... 30 图 3-6 调谐器增益调整流程 ......................................................................... 31 图 3-7 系统自动增益控制环路 ...................................................................... 32 图 3-8 系统控制状态图................................................................................. 34 图 3-9 增益核心算法状态图 ......................................................................... 36 图 3-10 增益调整流程图............................................................................... 38

IV 图 3-11 功率检测器输入输出关系................................................................. 39 图 3-12 功率检测器的编码 ........................................................................... 39 图 3-13 线性化编码后 PWD 输出功率与输出功率码关系 ............................. 40 图 3-14 幅度检测器的编码 ........................................................................... 41 图 3-15 线性化编码后 RSSI 输出功率与输出功率码关系 ............................. 41 图 3-16 RC 校正状态转换图 ........................................................................ 42 图 3-17 功率检测器的直流校正流程 ............................................................. 43 图 3-18 二分法校正过程............................................................................... 43 图 3-19 脉宽调制译码模块 ........................................................................... 44 图 3-20 占空比的校正 .................................................................................. 44 图 3-21 除法控制模块状态图 ....................................................................... 45 图 3-22 系统可知的 3 个信号位置 ................................................................ 45 图 3-23 P1 = P2 = P3 .................................................................................... 46 图 3-24 P1 > P2 = P3 .................................................................................... 46 图 3-25 P1 > P2 > P3 .................................................................................... 46 图 3-26 P1 = P2 > P3 .................................................................................... 47 图 3-27 多级系统中增益分配对非线性和噪声的影响 .................................... 48 图 3-28 Mixer 增益模式选择模块状态图 ....................................................... 48 图 4-1 系统各级的输出................................................................................. 49 图 4-2 PWD 及两个 RSSI 的输出 ................................................................. 49 图 4-3 系统控制流程 .................................................................................... 50 图 4-4 二分法增益设置................................................................................. 50 图 4-5 线性法增益设置................................................................................. 50 图 4-6 电阻电容校正模块仿真 ...................................................................... 51 图 4-7 功率检测器直流校正模块仿真 ........................................................... 51 图 4-8 脉宽调制译码模块仿真 ...................................................................... 52 图 4-9 自动增益控制下各级增益的变化........................................................ 53 图 4-10 脉宽调制译码模块测试结果 ............................................................. 53