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Spectral Breathing and Its Mitigation in Digital Fractional-N PLLs
数字分数N锁相环中的频谱呼吸现象及其多速率动态元件匹配解决方案
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数字锁相环频谱呼吸分数N分频动态元件匹配噪声消除
▸创新点1：首次实验验证数字锁相环中的频谱呼吸现象（系统创新）。通过详实的实验数据揭示了DCO元件失配导致的相位噪声谱周期性波动现象，填补了该领域未被充分研究的空白。
▸创新点2：提出多速率动态元件匹配技术（方法创新）。通过动态轮换DCO控制元件的工作时序，将失配误差均匀分布在Nyquist带宽内外，实测相位噪声波动幅度降低15dB以上。
▸创新点3：开发失配噪声消除技术（电路创新）。采用数字辅助校准技术构建失配误差前馈路径，在65nm CMOS工艺下实现带内相位噪声优化至-112dBc/Hz@1MHz。
▸创新点4：建立频谱呼吸量化分析模型（理论创新）。首次推导出频谱呼吸幅度与DCO非线性度的数学关系，为后续研究提供理论框架。
Abstract
Although digital phase-locked loops (PLLs) offer
several advantages over their analog counterparts, they suffer
from a major disadvantage that is rarely mentioned in pub-
lished articles. The disadvantage, known as spectral breathing,
is caused by component mismatches among the frequency control
elements within a PLL’s digitally controlled oscillator (DCO). The
mismatches introduce DCO frequency modulation nonlinearity
which fluctuates and, therefore, causes erratic variations in the
PLL’s measur