基于DDS的Ka频段小步进捷变频频率综合器设计

摘要

In communication,radar and electronic countermeasure systems,the frequency step and switch time of frequency synthesizer greatly affect the performance of the system.According to theoretical analysis and comparison on DDS and PLL,combining of their advantages,a detailed scheme of Ka-band frequency synthesizer with small frequency step and frequency agility is proposed using the AD Company's latest DDS-AD9914.The phase noise,spur rejection and frequency switch time of frequency synthesizer are analyzed in theory.The experimental results show that the frequency step of the proposed frequency synthesizer is down to 300 Hz,and its frequency switch time is less than 10 μs within the output frequency range of 24 GHz to 32 GHz.%在通信、雷达和电子对抗系统中,频率综合器的频率步进、换频时间对系统的指标有重要影响.基于对DDS和锁相合成方式的理论分析和比较,结合DDS与锁相合成方式的优点,通过使用AD公司的最新DDS产品AD9914和优化设计,提出一种Ka频段宽带小步进捷变频频率合成器的实现方案,对合成器的相位噪声、杂散抑制和换频时间指标进行了理论分析.结果表明,该频率综合器在24~32 GHz输出频率下,最小频率步进可以达到300 Hz,换频时间优于10 μs.