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锁相技术是现代通信的基础,而集成锁相环(PLL)则为现代通信提供了一种强有力的电子器件,大大促进了现代通信技术的发展。国产单片模拟集成PLLKD802~*就属该类器件。应用它可以方便地实现频率跟踪、锁相式倍频、分频、移频以及调频信号解调等。图1为KD802方框图。它由鉴相器(PD)、压控振荡器(VCO)、低通滤波器(LPF)、放大器(A)、限幅器以及内部稳压和温度补偿网络组成。PD比较输入信号和VCO输出信号的相位,产生一个与相位差相关的误差电压,该电压控制VCO的振荡频率,使之向输入信号的频率靠拢而实现频率自动跟踪。LPF则滤除高频成份和防止干扰。与分立元件组成的PLL相比,KD802不仅体积小、
Phase-locked technology is the basis of modern communications, and integrated phase-locked loop (PLL) provides a powerful electronic device for modern communications, greatly contributing to the development of modern communications technology. Domestic single chip analog integrated PLLKD802 ~ * belongs to this kind of device. Application It can easily achieve frequency tracking, phase-locked multiplier, frequency division, frequency shift and frequency modulation signal demodulation. Figure 1 for the KD802 block diagram. It consists of a phase detector (PD), a voltage controlled oscillator (VCO), a low pass filter (LPF), an amplifier (A), a limiter, and an internal regulator and temperature compensation network. The PD compares the phases of the input signal and the VCO output signal to produce an error voltage related to the phase difference that controls the oscillation frequency of the VCO to bring it closer to the frequency of the input signal to achieve automatic frequency tracking. The LPF filters out high-frequency components and prevents interference. Compared with the discrete component PLL, KD802 not only small size,