一、前言近年来在单片锁相环集成电路及高速分频器方面有长足的发展,使得数字式频率合成器的研制工作变得较为简单。在很大程度上克服了以往存在的电路庞大复杂、技术难度大和成本高等一系列问题。过去令人生畏的锁相环技术,现在有可能为设计师们广泛接受了。例如莫托罗拉公司生产的单片超高频锁相环集成电路MC145152,28脚 I. Preface In recent years, monolithic PLL integrated circuits and high-speed divider has made great progress, making the development of digital frequency synthesizer becomes more simple. To a large extent, it overcomes the problems of huge and complex circuits, high technical difficulties and high costs that existed in the past. The daunting phase-locked loop technology of the past may now be widely accepted by designers. For example, Motorola’s monolithic UHF PLL IC MC145152, 28 feet