程控濾波器設計

測控論文編號:CK066   論文字數:12387,頁數:37

目 錄
摘要……………………………………………………………………………. . .……………..Ⅱ
1 前言…………………………………………………………………………………………. .1
 1.1  什么是濾波器………………………………………………………………………… 1
 1.2  濾波器的發展………………………………………………………………………… 1
 1.3  單片機的應用領域與發展趨勢……………………………………………………… 2
 1.4  課題背景……………………………………………………………………………… 2
 1.5  設計要求……………………………………………………………………………… 3
2 總體設計方案………………………………………………………………………….  . .5
2.1  系統總體結構…………………………………………………………………….  …5
2.2  各部分性能指標……………………………………………………………………... .5
3  各部分設計方案………………………………………………………………………. .. 7
 3.1  可控增益放大器方案……………………………………………………………… . 7
 3.2  程控濾波器方案………………………………………………………………………7
 3.3  橢圓濾波器方案………………………………………………………………………8
 3.4  幅頻特性分析儀方案…………………………………………………………………8
4 理論分析與計算…………………………………………………………. ………………. 9
 4.1  低通濾波器參數選取…………………………………………………………………9
 4.2  高通濾波器參數選取…………………………………………………………………9
 4.3  橢圓濾波器參數選取……………………………………………………. ………… 11
5  系統電路設計………………………………………………………………………. ..……14
 5.1  程控放大器電路設計…………………………………………………………………14
 5.2  低通濾波器電路設計…………………………………………………………………15
5.3  高通濾波器電路設計…………………………………………………………………16
 5.4  橢圓濾波器電路設計…………………………………………………………………17
 5.5  簡易幅頻特性分析儀電路設計………………………………………………………18
6  系統電路設計……………………………………………………………………………...20
7  測試方法與測試結果…………………………………………………………………….22
 7.1  測試儀器………………………………………………………………………………22
 7.2  程控放大器電路測試…………………………………………………………………22
 7.3  低通濾波器電路測試…………………………………………………………………22
 7.4  高通濾波器電路測試…………………………………………………………………22
 7.5  橢圓濾波器電路測試…………………………………………………………………22
 7.6  簡易幅頻特性分析儀測試……………………………………………………………23
8  設計結果……………………………………………………………………………………24
9  LTC1068……………………………………………………………………………………25
 9.1  LTC1068簡介…………………………………………………………………………25 
 9.2  LTC1068內部結果和工作模式………………………………………………………27
 9.3  總結LTC1068…………………………………………………………………………29
10 論文總結……………………………………………………………………………………30
11 致謝………………………………………………………………………………... ………31
12  參考文獻……………………………………………………………………………………32

摘  要
 隨著濾波系統在各類電子裝置中的普遍使用，普通的濾波器在工作時產生的誤差，會影響整個系統的精確度。低精度的濾波器在使用時會造成很多不良后果，本課題基于單片集成可編程濾波器芯片的程控濾波器設計有著極其重要的意義。當輸入信號幅度變化時，通過前級的程控增益放大模塊實現對增益的精確控制最終使輸出信號幅度基本保持穩定；而對于輸入信號頻率的改變，借助單片集成可編程濾波器芯片的同時輔以簡單的外圍器件，采用編程數據來完成RC網絡的切換, 通過單片機編程對各種低頻信號實現低通，高通(帶通，帶阻以及全通)濾波處理，而且濾波的特性參數如中心頻率，品質因數等也可以根據不同的應用場合適當進行設置。提高了濾波器的性能和指標的同時避免了傳統有源濾波器電路濾波特性參數精度不高、電路復雜、設計和調試麻煩等難題，可以很好的應用于信號頻率及幅度在寬范圍內變化的場所，操作方便，性能優良。本次研究設計一個程控濾波器，放大器增益可設置，低通或高通濾波器通頻帶，截止頻率等參數可設置。
關鍵詞：程控  濾波器  單片機

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