频率源是雷达、通信、电子对抗与电子系统实现高性能指标的关键，很多现代电子设备和系统的功能都直接依赖于所用频率源的性能，因此频率源被人们喻为众多电子系统的“心脏”。而当今高性能的频率源均通过频率合成技术来实现。频率合成器是利用一个或多个标准信号，通过各种技术途径产生大量离散频率信号的设备。传统的频率合成器有直接模拟合成法与锁相环合成法两种。直接模拟合成法利用倍频、分频、混频及滤波，从单一或几个参考频率中产生多个所需的频率。该方法频率转换时间快（小于100ns），但是体积大、功耗大，目前已基本不被采用。锁相环式频率合成器具有很好的窄带跟踪特性，可以很好地选择所需频率的信号，抑制杂散分量，并且避免了大量的滤波器，有利于集成化和小型化。但存在高分辨率和快转换速度之间的矛盾，一般只能用于大步进频率合成技术中。
Frequency is the source of radar, communications, electronic warfare and electronic systems to achieve the key performance indicators, many modern electronic equipment and the function of the system are directly dependent on the frequency used by the source of the performance, the frequency source been numerous electronic system known as the "heart . " And the frequency of today''s high-performance all through the frequency of the source technology to achieve. Synthesis is the use of one or more standard signal, through various technical means of a large number of discrete frequency signal equipment. Synthesis of traditional direct analog synthesis and PLL synthesis of two. Direct analog synthesis using frequency, frequency, mixing and filtering, from a single or a few reference frequency generated more than the required frequency. The method frequency
4700字
