摘要:本论文在现有放大器的基础上进行借鉴和研究，设计出的宽频带放大器主要由各级放大模块、数模转换模块、增益可调模块等几个功能性模块构成。该系统的微处理器为AT89c51，增益自动可调单元选择为AD603器件，具有增益预置和程控功能，能实现5分贝步距间隔的连续调节，并使其增益不超出负20分贝到正的60分贝的范围。在频带宽度10兆赫兹以下，其增益波动不超过1分贝。该系统的主要运行过程就是先对放大输出信号进行检波处理，再通过模数转换器使其变为数字信号，便可以结合单片机，进行增益自动控制，通过改变元器件的参数和利用并联、级联的方式，即可使最终输出信号达到要求中的放大倍数，且具有稳定性和可靠性。50931

毕业论文关键词：放大器；增益控制；AD603 

The Design of Wideband DC Amplifier

Abstract: In this paper on the basis of other theories of amplifier for reference and research, design of broad band amplifier at all levels mainly by amplifying module, digital to analog conversion module, gain adjusting module, and several other functional modules. The system of microprocessor AT89C51 and gain automatic adjusting unit selection for AD603 device with preset and gain programmable function, can realize 5 dB step spacing adjusted continuously, and the gain does not exceed the negative 20 dB to 60 dB range. In the frequency band width below 10 MHz, the gain fluctuation is not more than 1 db. The main operation process of the system is now to the amplifier output signal demodulation processing, again by an analog-to-digital converter (ADC) the change to digital signals can be combined with the SCM, automatic gain control, by changing the parameters of the components and the use of parallel, cascade, can make the total output signal reaches the requirements of magnification and high stability and reliability.

Key Words: Amplifiers; Gain control; AD603

目  录

摘要 1

引言 2

1.宽频带放大器的背景与研究 2

1.1概述 2

1.2宽频带放大器的应用前景 2

1.3课题研究 2

2.系统模块的总设计 3

2.1宽频带放大器的理论基础 3

2.2主要模块与电路 3

2.3系统框图设计 5

3.理论分析与计算 6

3.1宽带增益积 6

3.2通频带内增益起伏控制 6

3.3线性相位 7

3.4抑制直流零点漂移 7

3.5改善放大器的稳定性 7

4.硬件设计 8

4.1跟随模块的设计 8

4.2差分放大电路的设计 8

4.3增益控制电路的设计 9

4.4补偿电路的设计 9

4.5后级功率放大电路的设计 9

4.6各级增益控制的设计 10

4.7通频带选择模块的设计 10

4.8程控放大电路的设计 10

4.9电源模块的设计 10

5.系统软件流程图设计