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毕业设计 高频锁相环设计,共17页,5061字。
摘要：锁相环是个相位误差控制系统，相位比较器将检测输入信号和输出信号的相位差，再把信号转换成UD电压输出信号，此信号经低通滤波器滤波后形成压控振荡器的控制电压UC，对振荡器输出信号的频率实施控制。锁相环由鉴相器、环路滤波器和压控振荡器组成。鉴相器是鉴别输入信号Ui与输出信号Uo之间的相位差 ，并输出误差电压Ud。Ud 中的噪声和干扰成分被低通性质的环路滤波器滤除 ，形成压控振荡器（VCO）的控制电压Uc。Uc作用于压控振荡器的结果是把它的输出振荡频率f。拉向环路输入信号频率fi ，当二者相等时，环路被锁定 ，称为入锁。维持锁定的直流控制电压由鉴相器提供，因此鉴相器的两个输入信号间留有一定的相位差。
Abstract: The phase-locked loop will be the phase error control system, the phase comparator will examine the input signal and the output signal phase difference, again signal conversion UD voltage output signal, this signal after low pass filter filter will form the pressure to control oscillator’s control voltage UC, to oscillator output signal frequency implementation control. The phase-locked loop by the discriminator, the ring circuit filter and the pressure controls the oscillator to be composed. The discriminator is distinguishes input signal Ui and between the output signal Uo phase difference, and outlet error voltage Ud. In the Ud noise and the disturbance ingredient by the low pass nature’s ring circuit filter filtration, are formed the pressure controls the oscillator (VCO) control voltage Uc. Uc affects Yu Yakong oscillator’s result is its output oscilation frequency f. Pulls to loop input signal frequency fi, when the two are equal, the ring circuit is locked, is called into the lock. The maintenance locking cocurrent control voltage provides by the discriminator, therefore between the discriminator two input signal leaves leeway certain phase difference.
关键词：鉴相器，环路滤波器，压控震荡器，AD9901，74LS124。
Key word: The discriminator, the ring circuit filter, the pressure controls the oscillator, AD9901,74LS124.
1 前言 3
2 锁相环工作原理 4
2.1 锁相环的功能 4
2.2锁相环各单元的工作原理 4
2.2.1 鉴相器 4
2.2.2 环路滤波器我们选择比例积分滤波器，其电路图如图1.3所示 5
2.2.3 压控滤波器 5
2.3锁相环工作过程 6
3单元模块设计 8
3.1 AD9901芯片介绍 8
3.2 环路滤波器 9
3.3 74LS124芯片介绍 11
6 参考文献 16
7 附录 17