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在用数字电路构成广泛应用于通信系统的同步提取及检波的锁相环实验过程中,大都存在一个共同的问题,即一旦提高抖动抑制效果,就会使同步范围变窄。这是因为利用量化相位差的信号只能控制系统的输出相位之缘故。本文所研究的锁相环为利用二值量化相位差的信号控制系统的输出相位,与此同时控制自由频率在宽带内进行同步,通过实验及分析确认了其工作原理。在分析过程中,求出了系统的自由频率固定情况下的输出相位分布,并以自由频率状态下的存在概率做为权重将其相加。所求得的输出抖动和同步状态与实验完全一致。使用这种锁相环,虽然可以将输出相位抖动抑制到很小,能扩大同步范围,但是在宽带内为了提高过渡特性,必须检测相位羞及频率差。
In the digital circuit is widely used in synchronous extraction and detection of the communication system phase-locked loop experiment, most have a common problem, once the increase jitter suppression, it will narrow the synchronization range. This is because the signal using the quantized phase difference can only control the output phase of the system. In this paper, the phase-locked loop is used to control the output phase of the system by using two-phase quantization phase difference signal, at the same time to control the free frequency to be synchronized in the broadband. The working principle is confirmed through experiment and analysis. In the process of analysis, the output phase distribution of the system under the condition of free frequency is obtained and added together with the existence probability under the condition of free frequency. The resulting output jitter and synchronization state are exactly the same as the experiment. Using this phase-locked loop, although the output phase jitter can be suppressed to a very small, can expand the synchronization range, but in the broadband in order to improve the transient characteristics, you must detect the phase ashamed and frequency difference.