pll电路的研究及在信号产生中的应用.doc

PLL电路的研究及在信号产生中的应用

摘    要

摘要：随着科学技术的发展，锁相环PLL是自动频率控制和自动相位控制技术的融合。鉴于其在通讯、航海、军事等发面的广泛应用，研究锁相环电路的特性有助于了解和提高锁相环电路的性能指标，使其在各领域得到更为广泛的应用和推广，其具有很强的实际应用价值。

本设计基于数字锁相环式频率合成技术,采用AT89S52单片机完成电压控制LC振荡器的控制。可控制单片机改变频率，步进为100KHz；可实时测量压控振荡器输出频率、输出电压峰—峰值，并用数码管显示器显示；在输出负载为容性阻抗时，用一个串联谐振回路提高其输出功率；采用了交流电压反馈和AGC电路来稳定输出电压；末级功放选用三极管2SC2668，使其工作在丙类放大状态，提高了放大器的效率；输出正弦波比较稳定，没有明显失真；输出频率稳定度达到10-3；输出功率≥20mW；输出电压可稳定在1V±0.1V。

关键词：锁相环；压控振荡器；频率测量；信号产生；单片机

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    录

１ 引言 1

2系统组成 3

3方案论证与比较 4

3.1压控振荡器方案论证与选择 4

3.2频率合成器的设计方案论证与选择 4

3.3控制模块的设计方案论证与选择   5

3.4电源方案的选择 5

4锁相环 7

4.1锁相环的概念 7

4.2锁相环基本框图 7

4.3鉴相器的时序图 8

4.4捕捉带与通频带 9

5单元电路的设计 10

5.1压控振荡器 10

5.1.1压控振荡器MC1648 11

5.1.2压控振荡电路设计 11

5.1.3变容二级管与开关二级管切换电路 12

5.2锁相环式频率合成器的设计 12

5.2.1锁相环控制电路设计 12

5.2.2 MC145163的管脚图与内部组 13

5.2.3 MCl45163P的相位比较器 14

5.3低通滤波器 15

5.4电源电路设计 16

5.5电子控制单元电路（ECU） 16

5.5.1 89C52单片机的管脚说明 16

5.6频率测量显示电路 20

6 软件设计 21

7 测试结果 23

8 结论 24

9参考文献 25

致谢 26

附录１：系统原理图 27

附录2：环境参数检测程序 28