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An Ultra-Compact Differentially Tuned 6-GHz CMOS LC-VCO With Dynamic Common-Mode Feedback
提出一种超紧凑差分调谐6GHz LC-VCO，适用于6+Gb/s高速串行链路。
90nm CMOS, 1.6V, 14mW, 4.5-7.1GHz, 117.7dBc/Hz@3MHz
LC-VCO差分调谐共模电压高速串行链路CMOS
▸创新点1：动态设置共模电压 - 该方法创新通过动态调整差分变容二极管控制信号的共模电压，使其与VCO的共模电压一致，无需额外功耗，且能精确跟踪振荡期间的输出共模电压。
▸创新点2：超紧凑设计 - 该电路创新实现了0.024 mm²的极小面积，是目前报道中6 GHz频率下最小的LC-VCO，面积与环形振荡器相当但相位噪声显著更优。
▸创新点3：宽调谐范围 - 该电路创新采用差分控制技术，实现了4.5 GHz至7.1 GHz的宽调谐范围（45%），显著提升了频率覆盖能力。
▸创新点4：低相位噪声 - 该电路创新在5.63 GHz载波频率下，3 MHz偏移处的相位噪声低至-117.7 dBc/Hz，同时仅消耗14 mW功耗，性能优异。
Abstract
A fully integrated 0.024 mm /50differentially tuned 6-GHz LC-VCO for 6+Gb/s high-speed serial (HSS) links in 90-nm bulk CMOS is presented. It is smaller than any LC-VCO reported to date at this frequency. Its size is comparable with ring oscilla- tors but it has significantly better phase noise. A circuit technique is introduced to dynamically set the common-mode (CM) voltage of the differential varactor control signals equal to the VCO’s CM. Compared to other commonly used techniques such as replica biasing, this technique does not dissipate any extra power and it accurately tracks the output common-mode voltage of the VCO during the oscillations. Using a differential control a very wide tuning range from 4.5 GHz to 7.1 GHz (45%) is achieved. The VCO has a measured phase noise of 117.7 dBc/Hz at a 3-MHz offset from a 5.63-GHz carrier while dissipating 14 mW from a 1.6-V supply.