A VCO with Implicit Common-Mode Resonance

📋 论文概要

该论文提出了一种具有隐式共模谐振的VCO拓扑，通过巧妙的设计实现了共模谐振而无需额外的电感，解决了传统VCO中由于差分对晶体管进入三极管区导致的品质因数退化问题。该设计在不增加面积和功耗的前提下，提升了VCO的相位噪声性能。

💡 主要创新点

• 提出隐式共模谐振技术，利用内部寄生参数实现共模谐振，避免额外电感，节约芯片面积。
• 通过提高共模阻抗在2倍LO频率处，防止差分对晶体管进入三极管区，保持高Q值。

🏷 关键词

📄 原文摘要

CMOS VCO performance metrics have not improved significantly over the last decade. Indeed, the best VCO Figure of Merit (FOM) currently reported was published by Hegazi back in 2001 [1]. That topology, shown in Fig. 25.3.1(a), employs a second resonant tank at the source terminals of the differential pair that is tuned to twice the LO frequency (FLO). The additional tank provides a high common-mode impedance at 2×FLO, which prevents the differential pair transistors from conducting in triode and thus prevents the degradation of the oscillator’s quality factor (Q). As a consequence, the topology can achieve an oscillator noise factor (F) – defined as the ratio of the total oscillator noise to the noise contributed by the tank – of just below 2, which is equal to the fundamental limit of a cross-coupled LC CMOS oscillator [2]. There are, however, a few drawbacks of Hegazi’s VCO: (1) the additional area required for the tail inductor,

👥 作者与机构

David Murphy, Hooman Darabi, Hao Wu

Broadcom, Irvine, CA