随着人们生活水平的不断提高,单片机控制无疑是人们追求的目标之一，它所给人带来的方便也是不可否定的，其中数字温度计就是一个典型的例子，但人们对它的要求越来越高，要为现代人工作、科研、生活、提供更好的更方便的设施就需要从数单片机技术入手，一切向着数字化控制，智能化控制方向发展。人们迫切地要求能够远距离随时随地迅速而准确地传送多媒体信息。于是，无线通信技术得到了迅猛的发展，技术也越来越成熟。而宽带放大器是上述通信系统和其它电子系统必不可少的一部分。本设计根据增益控制的原理，在完成增益指标和自制稳压电源的同时，也考虑了实际使用效果，来提高放大器带负载的能力。

本设计介绍的是基于单片机的程控放大器，其由三个模块电路构成：交流放大器、增益控制和单片机键盘显示处理模块。交流放大器采用自举式同相交流放大器，提高交流放大器的输入电阻，从而提高了共模抑制比。增益控制采用继电器的导通和关断来控制反馈电阻的大小，以实现增益大小的变化。单片机键盘显示处理模块主要采用1602液晶显示，通过按键盘控制以实现显示不同的增益。

 

关键词：AT89C51单片机；DAC0832；数模转换器；运算放大器

Abstract

 

With the continuous improvement of people's living standards, single-chip control is undoubtedly one of the goals pursued by people, it brings the convenience is also undeniable, which is a typical digital thermometer example, but it is more and more of its requirements The higher the need for modern work, research, life, to provide better and more convenient facilities need to start from the number of single-chip technology, all toward the digital control, intelligent control direction. There is an urgent need to be able to transmit multimedia information quickly and accurately anywhere, anytime. As a result, wireless communication technology has been rapid development, technology is more and more mature. And broadband amplifiers are indispensable parts of the above communication systems and other electronic systems. The design of the principle of gain control, in the completion of the gain indicators and self-regulated power supply at the same time, also consider the actual use of the effect, to improve the amplifier with load capacity.

This design is based on the single-chip programmable amplifier, which consists of three modules: AC amplifier, gain control and single-chip keyboard display processing module. The AC amplifier uses a bootstrap phase AC amplifier to increase the input resistance of the AC amplifier, thereby increasing the common mode rejection ratio. The gain control uses the relay on and off to control the size of the feedback resistor to achieve a change in gain size. Single-chip keyboard display processing module is mainly used 1602 LCD display, by pressing the keyboard control to achieve the display of different gains.

 

Key words: AT89C51 microcontroller; DAC0832; digital-to-analog converter; operational amplifier