A Wideband Fractional-N Ring PLL with FractionalSpur Suppression Using Spectrally Shaped Segmentation

📋 论文概要

该论文提出了一种采用频谱整形分段技术的宽带分数N环形PLL，用于抑制分数杂散。通过改进相位插值器中的增益误差和非线性问题，实现了宽带宽和低杂散性能。

💡 主要创新点

• 提出频谱整形分段技术，有效抑制分数N PLL中的分数杂散。
• 在环形振荡器架构下实现宽带分数N PLL，同时保持较低的杂散水平。

🏷 关键词

📄 原文摘要

Fractional-N PLLs play an important role in both wireless and wireline circuits. Finer timing resolution is needed to reduce the quantization noise in the phase domain. In conventional designs, a phase interpolator (PI) is used to suppress the quantization noise due to its simplicity, but at a cost of gain error and nonlinearity. These sub-phase non-idealities result in large fractional spurs [2-5]. Techniques for reducing these spurs include using a PI mismatch and spur-cancellation scheme [2], digital correlation and cancellation [3], use of a successive requantizer with switched loop filter and offset charge-pump [4], and foreground calibration [5]. This paper presents a ring-oscillator based 2MHz bandwidth fractional-N PLL that uses a spectrally shaped segmented-feedback approach to alleviate fractional spurs induced by the PI non-idealities. This approach results in a compact design and, in contrast to previous work, achieves a 26dB spur reduction without need of correlation, ca

👥 作者与机构

Tsung-Kai Kao1, Che-Fu Liang1, Hsien-Hsiang Chiu1, Michael Ashburn2

MediaTek, Hsinchu, Taiwan, 2MediaTek, Woburn, MA