An X-band frequency synthesizer based on the Fractional-N Phase Locked Loop(FNPLL) is designed.The frequency synthesizer,with the PLL with the integrated and embedded VCO adopted for the circuit,can realize the dot frequency output for any step and the big bandwidth linear frequency modulation(LFM) signal output within the range from 8.45 to 9.55GHz,featuring low phase noise,big bandwidth,high integration,small size,and low power consumption and cost.Finally,the test results are given,including the spectrum test charts as well as the curves of the frequency hopping time and the phase noise.%介绍了一种基于小数分频锁相技术的X波段频率合成器的设计方法。该频率合成器采用了内部集成VCO的锁相芯片进行电路设计,可在8.45～9.55 GHz频率范围内实现任意步进点频输出,并可实现大带宽线性调频信号输出,具有低相位噪声、大带宽、高集成度、小体积、低功耗和低成本等优点。最后给出了频率合成器的测试结果,包括信号的频谱测试图、跳频时间测试曲线和相位噪声测试曲线等。
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