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中南民族大学 计算机科学学院

电子设计竞赛报告

竞赛题目 可变增益宽带直流放大器 学院 计算机科学学院 专业 自动化 参赛学生 组长 陈明 学号 2012213408 联系电话 18202743137 组员 邓贵 学号 2012213477 组员 雷建国 学号 2012213457 指导老师 王超 张志俊

自动化电赛实验室 12级测控组

中南民族大学 计算机科学学院

通用可变增益放大器（D）

摘要

通过对目前放大器的增益和控制方法进行分析和比较，该设计提出了一种简

单易行的控制方案，采用了分级设计匹配互连的思想。该设计分为电源部分、电压控制放大部分、档位选择控制部分、两级固定增益部分和后级电压输出部分。此设计通过继电器对各个部分的连接进行匹配切换，使整个系统的放大倍数在所需的-20dB~0dB，0dB~20dB，20dB~40dB，40dB~60dB四个档位之间转换。通过最后一级功率的放大，使输出部分获得幅度远大于±8V，并且很好的抑制了零点漂移问题。该设计除了满足题目的基本部分和发挥部分要求外，我们还充分发挥各级之间的创新，并把它融入系统中，设计出一个可控范围大、输出稳定高、低温漂、幅频特性良好、抗干扰能力强的可变增益放大器。该设计采用单端输入，单端输出方式实现增益连续调节，输入阻抗有50Ω和大于10MΩ可选，电路输出阻抗有0Ω和50Ω可选。

ABSTRACT

Through the current amplifier gain and control methods for analysis and comparison of the design of a simple control scheme is proposed , using a hierarchical design to match the interconnect ideas. The design is divided into power section , the voltage control amplification section , gear selection control section , rear section and two fixed gain level voltage output section. By this design of various parts of the relay connection switching match , so the magnification of the entire system 0dB, 0dB ~ 20dB, 20dB ~ 40dB, 40dB ~ 60dB conversion between four gear required -20dB ~. By the end of a power amplification, the output section to get much larger than ± 8V, and good suppression of the zero drift problem. In addition to meeting the basic part of the design of the subject and played part of the requirements , we also give full play between levels of innovation , and put it into the system , the design of a controllable range, high output stability , low temperature drift , amplitude-frequency characteristics good , strong anti-jamming capability variable gain amplifier. The design uses a single-ended input , single-ended output achieved continuous gain adjustment, input impedance of 50Ω and greater than 10MΩ optional circuit output impedance of 0Ω and 50Ω optional

12级自动化 2

中南民族大学 计算机科学学院

目录

目录................................................................................................................................................... 3 要求................................................................................................................................................... 4

1、基本要求 ............................................................................................................................. 4 2．发挥部分 ............................................................................................................................. 4 一、方案论证与比较 ....................................................................................................................... 4

1、电压控制放大部分 ............................................................................................................. 5

方案一： ........................................................................................................................... 5 方案二： ........................................................................................................................... 5 方案三： ........................................................................................................................... 5 2、档位选择控制部分 ............................................................................................................. 5

方案一： ........................................................................................................................... 5 方案二： ........................................................................................................................... 5 方案三： ........................................................................................................................... 5 3、末级电压输出部分 ............................................................................................................. 6

方案一： ........................................................................................................................... 6 方案二： ........................................................................................................................... 6 方案三： ........................................................................................................................... 6

二、 系统设计 ................................................................................................................................. 7

A.硬件设计部分 ....................................................................................................................... 7 1、总体设计思路 ..................................................................................................................... 7 2、主要电路原理分析与计算 ................................................................................................. 7

2.1、电压控制放大部分 .................................................................................................. 7 2.2、档位控制及固定增益部分 ...................................................................................... 9 2.3、末级电压输出部分 ................................................................................................ 10 B.软件设计部分 ..................................................................................................................... 11 三、系统测试方法与测试数据 ..................................................................................................... 12

1、测试仪器 ........................................................................................................................... 12 2、测试方法与测试数据 ....................................................................................................... 12 3、测试结果分析 ................................................................................................................... 14

3．1测试结果分析 ........................................................................................................ 14 3．2误差分析 ................................................................................................................ 14 3．3 测试心得 ............................................................................................................... 14

四、总结 ......................................................................................................................................... 14 五、 附录1 .................................................................................................................................... 14 附录2.............................................................................................................................................. 14

12级自动化 3