Research Of Sampling Phase Locked Frequency Synthesizer

Frequency source is widely used in today's electronic equipment and even refered as "a heart" of many electronic systems.The frequency synthesizer with a lot of channels and high frequency stability by means of theory of phase locking has almost been a necessary component in the modern electronic systems such as telecommunication , radar and electronic countermeasure.The phase-locked frequency synthesizer can be generally divided into two kinds:one is digital phase locked frequency synthesizer,the other is analog sampling phase locked frequency synthesizer.Compared with the prior,the latter has many merits such as lower phase noise,samller volume,lighter weight and lower power consumption and has a wide foreground in the equipments of microwave band.The basic operation principle of phase-locked frequency synthesizer and the type of circuits are expatiated systematicly in this paper.The principle of operation on sampling phase detector and some characteristics including the linear tracking and phase noise in phase loop circuits are analyzed deeply.The research is emphased on the theory and design method of circuits in the sampling phase-locked frequency synthesizer. Then,the expansion capturing circuit is analyzed and designed for better performance of capturing loop circuits.At last,the loop filter is also analyzed and contrived taking account of effection of additional phase shift by the sampling-holder.The general research on the theory and technology of sampling phase lock in the paper will make a basement for the development of new product.