PLL電路的研究及在信號產生中的應用

摘    要

摘要：隨著科學技術的發(fā)展，鎖相環(huán)PLL是自動頻率控制和自動相位控制技術的融合。鑒于其在通訊、航海、軍事等發(fā)面的廣泛應用，研究鎖相環(huán)電路的特性有助于了解和提高鎖相環(huán)電路的性能指標，使其在各領域得到更為廣泛的應用和推廣，其具有很強的實際應用價值。

本設計基于數字鎖相環(huán)式頻率合成技術,采用AT89S52單片機完成電壓控制LC振蕩器的控制?？煽刂茊纹瑱C改變頻率，步進為100KHz；可實時測量壓控振蕩器輸出頻率、輸出電壓峰—峰值，并用數碼管顯示器顯示；在輸出負載為容性阻抗時，用一個串聯諧振回路提高其輸出功率；采用了交流電壓反饋和AGC電路來穩(wěn)定輸出電壓；末級功放選用三極管2SC2668，使其工作在丙類放大狀態(tài)，提高了放大器的效率；輸出正弦波比較穩(wěn)定，沒有明顯失真；輸出頻率穩(wěn)定度達到10-3；輸出功率≥20mW；輸出電壓可穩(wěn)定在1V±0.1V。

關鍵詞：鎖相環(huán)；壓控振蕩器；頻率測量；信號產生；單片機

ABSTRACT

Abstract: Along with the science technical development, lock mutually the wreath PLL is mutually automatic frequency control and auto control technical fusion. Owing to it is in the hair noodleses, such as communication, voyage and military...etc. of extensive applied. The research lock mutually the characteristic of wreath electric circuit help understanding and exaltation to lock mutually the function index sign of wreath electric circuit, Make it get more extensive application and expansion in each realm, it has very strongly physically applied value.

The system adopting AT89S52 to design the VCO is based on the digital frequency synthesize technical .The digital PLL principle is used and the control of the core chip MC145163 is accomplished by AT89S52. It can automatically change and measure the frequency of VCO with a step of 100 kHz and VP-P and display it by LED .Meantime it realizes the functions of expanding the frequency, which make more practical. The design is program with AT89S52 . It is proved to be well functioning, the output frequency is stable and the power of is over 20mW, and the capability indexes are also good after testing.

Key Words：PLL;voltage controlled oscillator; frequency measure; signal-generating; SMCU

目    錄

１ 引言 1

2系統組成 3

3方案論證與比較 4

3.1壓控振蕩器方案論證與選擇 4

3.2頻率合成器的設計方案論證與選擇 4

3.3控制模塊的設計方案論證與選擇   5

3.4電源方案的選擇 5

4鎖相環(huán) 7

4.1鎖相環(huán)的概念 7

4.2鎖相環(huán)基本框圖 7

4.3鑒相器的時序圖 8

4.4捕捉帶與通頻帶 9

5單元電路的設計 10

5.1壓控振蕩器 10

5.1.1壓控振蕩器MC1648 11

5.1.2壓控振蕩電路設計 11

5.1.3變容二級管與開關二級管切換電路 12

5.2鎖相環(huán)式頻率合成器的設計 12

5.2.1鎖相環(huán)控制電路設計 12

5.2.2 MC145163的管腳圖與內部組 13

5.2.3 MCl45163P的相位比較器 14

5.3低通濾波器 15

5.4電源電路設計 16

5.5電子控制單元電路（ECU） 16

5.5.1 89C52單片機的管腳說明 16

5.6頻率測量顯示電路 20

6 軟件設計 21

7 測試結果 23

8 結論 24

9參考文獻 25

致謝 26

附錄１：系統原理圖 27

附錄2：環(huán)境參數檢測程序 28