一种超低相位噪声宽带频率合成器的设计

摘要

Based on theoretical analysis on double⁃loop presetting technology and harmonic frequency mixing,combining the fre⁃quency mixing PLL synthesizing method with high⁃order frequency multiplication synthesizing method,a detailed low⁃cost scheme of wideband fine⁃resolution frequency synthesizer with ultra low phase noise is proposed by using unconventional design of variable phase detect polarity.The theoretical analysis on phase noise and spur rejection specifications of this scheme is performed. The experiment results show that this scheme realizes phase noise lower than-132 dBc/Hz@10 kHz,and spur rejection more than 70 dB at 8 GHz out⁃put.The method can provide some reference for design on wideband frequency synthesizer with ultra low phase noise.%基于对双环频率预置技术和谐波混频技术的理论分析，将混频锁相合成方式与高次倍频合成方式相结合，采用鉴相极性可变的非常规设计，提出一种宽带小步进超低相位噪声频率合成器的低成本实现方案，并对合成器的相位噪声和杂散抑制指标进行了理论分析。试验证明，在8 GHz输出频率下，方案实现了低于－132 dBc／Hz＠10 kHz的相位噪声和70 dB以上的杂散抑制性能。对宽带超低相位噪声频率合成器的设计具有借鉴意义。