选用内部时钟可达1GHz的高性能直接数字合成频率源DDS芯片AD9858作为核心器件设计频率合成器，采用DDS DSP SAWO的设计方案，设计成功905MHz低相噪、高稳定度的声表面波振荡器为AD9858提供参考时钟，整个系统采用高性能的DSP作为控制电路。文中详细阐述了AD9858芯片的主要性能及其在快速捷变频频率合成器设计中的应用方法。

The high performance DDS chip AD9858 produced by Analog Device Inc is adopted to design a frequency synthesizer in this paper. A design scheme of DDS +DSP +SAWO is adopted. The designed synthesizer has low phase noise and high stability SAW oscillator to offer a reference clock for AD9858. The whole system adopts high-performance DSP as the control circuit .The main performance characteristics of AD9858 chip and its application to frequency synthesizer with fast frequency hopping is mainly introduced in detail.

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