程控滤波器设计

范文编号:CK066   范文字数:12387,页数:37

摘  要
 随着滤波系统在各类电子装置中的普遍使用，普通的滤波器在工作时产生的误差，会影响整个系统的精确度。低精度的滤波器在使用时会造成很多不良后果，本课题基于单片集成可编程滤波器芯片的程控滤波器设计有着极其重要的意义。当输入信号幅度变化时，通过前级的程控增益放大模块实现对增益的精确控制最终使输出信号幅度基本保持稳定；而对于输入信号频率的改变，借助单片集成可编程滤波器芯片的同时辅以简单的外围器件，采用编程数据来完成RC网络的切换, 通过单片机编程对各种低频信号实现低通，高通(带通，带阻以及全通)滤波处理，而且滤波的特性参数如中心频率，品质因数等也可以根据不同的应用场合适当进行设置。提高了滤波器的性能和指标的同时避免了传统有源滤波器电路滤波特性参数精度不高、电路复杂、设计和调试麻烦等难题，可以很好的应用于信号频率及幅度在宽范围内变化的场所，操作方便，性能优良。本次研究设计一个程控滤波器，放大器增益可设置，低通或高通滤波器通频带，截止频率等参数可设置。
关键词：程控  滤波器  单片机

Abstract
 With the development of filter system in the various types of electronic devices, normal filter will generate error when it works, and it will affect the overall system accuracy. Low precision filters will cause many adverse consequences, the subject of integrated programmable filters based on single chip programmable filter design has an extremely important significance. When the input signal amplitude changes, with the front stage programmable gain amplifier module, we can achieve precise control to keep the output signal amplitude remain stable;
 while the input signal changes frequently, we  accomplish the RC network switch with monolithic integrated programmable filter chip and simple peripheral device by sampling program data;
 By microcontroller programming, we accomplish low-pass, high pass filtering on a variety of low-frequency signals, and  filter parameters such as center frequency, quality factor can be set properly according to different applications.
 Thus, we improve the performance and targets of filter, at the same time, we avoid the challenge which includes: the inaccuracy of characteristic parameter in traditional active filter, the complex design and debug of circuit, and it can be well applied  in suitation which signal frequency and amplitude changes in a wide range of place,it is easy to operate and has excellent performance.The study aims to design a Programmable filter which its amplifier gain,low-pass or high pass filter passband and the cut-off frequency can be set.
Keywords： Programmable  filter SCM

目 录
摘要……………………………………………………………………………. . .……………..Ⅱ
1 前言…………………………………………………………………………………………. .1
 1.1  什么是滤波器………………………………………………………………………… 1
 1.2  滤波器的发展………………………………………………………………………… 1
 1.3  单片机的应用领域与发展趋势……………………………………………………… 2
 1.4  课题背景……………………………………………………………………………… 2
 1.5  设计要求……………………………………………………………………………… 3
2 总体设计方案………………………………………………………………………….  . .5
2.1  系统总体结构…………………………………………………………………….  …5
2.2  各部分性能指标……………………………………………………………………... .5
3  各部分设计方案………………………………………………………………………. .. 7
 3.1  可控增益放大器方案……………………………………………………………… . 7
 3.2  程控滤波器方案………………………………………………………………………7
 3.3  椭圆滤波器方案………………………………………………………………………8
 3.4  幅频特性分析仪方案…………………………………………………………………8
4 理论分析与计算…………………………………………………………. ………………. 9
 4.1  低通滤波器参数选取…………………………………………………………………9
 4.2  高通滤波器参数选取…………………………………………………………………9
 4.3  椭圆滤波器参数选取……………………………………………………. ………… 11
5  系统电路设计………………………………………………………………………. ..……14
 5.1  程控放大器电路设计…………………………………………………………………14
 5.2  低通滤波器电路设计…………………………………………………………………15
5.3  高通滤波器电路设计…………………………………………………………………16
 5.4  椭圆滤波器电路设计…………………………………………………………………17
 5.5  简易幅频特性分析仪电路设计………………………………………………………18
6  系统电路设计……………………………………………………………………………...20
7  测试方法与测试结果…………………………………………………………………….22
 7.1  测试仪器………………………………………………………………………………22
 7.2  程控放大器电路测试…………………………………………………………………22
 7.3  低通滤波器电路测试…………………………………………………………………22
 7.4  高通滤波器电路测试…………………………………………………………………22
 7.5  椭圆滤波器电路测试…………………………………………………………………22
 7.6  简易幅频特性分析仪测试……………………………………………………………23
8  设计结果……………………………………………………………………………………24
9  LTC1068……………………………………………………………………………………25
 9.1  LTC1068简介…………………………………………………………………………25 
 9.2  LTC1068内部结果和工作模式………………………………………………………27
 9.3  总结LTC1068…………………………………………………………………………29
10 范文总结……………………………………………………………………………………30
11 致谢………………………………………………………………………………... ………31
12  参考文献……………………………………………………………………………………32

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