Purpose

Multiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the overall system. Different studies are devoted to efficient quadrature signals generation. This paper aims to present a new low-phase noise superharmonic injection-locked QVCO.

Design/methodology/approach

The proposed QVCO is comprised of two identical inductor-capacitor circuit (LC)-voltage-controlled oscillators (VCOs) in which second harmonics, with 180° phase shift, are injected from one core VCO to the gate of tail current source of the other VCO via a coupling capacitor. Using second harmonics with high amplitude will switch the tail from the inversion to the accumulation, and therefore, flicker noise is reduced. Also, because of the use of lossless and noiseless coupling elements, that is, coupling capacitors, and also because of the existence of an inherent high-pass filter, the proposed LC-QVCO has a good phase noise performance.

Findings

The introduced technique is designed and simulated in a commercial 0.18 µm radio frequency complementary metal oxide semiconductor (RF-CMOS) technology and 10 dB improvement of close-in phase noise is achieved (compared to the conventional method). Simulation results show that the phase noise of the proposed QVCO is −130.3 dBc/Hz at 3 MHz offset from 5.76 GHz center frequency, while the total direct current (DC) current drawn from a 0.9-V power supply is 4.25 mA (figure of merit = −190.2 dBc). Monte Carlo simulation results show that the figure of merit of the circuit has a Gaussian distribution with mean value and standard deviation of −189.97 dBc and 0.183, respectively.

Originality/value

This technique provides a new simple but efficient superharmonic coupling and noise shaping method that reduces close-in phase noise of superharmonic multiphase VCOs by switching of tail transistors with 2 ω0 (second harmonic of oscillation frequency). No extra devices such as area-consuming transformer or additional power-hungry oscillator are used for coupling.

中文翻译：

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一种新型尾部开关超谐波多相LC-VCO

目的

多相和正交压控振荡器 (QVCO) 在现代通信系统中起着关键作用，它们的相位噪声性能会影响整个系统的性能。不同的研究致力于有效的正交信号生成。本文旨在提出一种新的低相位噪声超谐波注入锁定 QVCO。

设计/方法/方法

提议的 QVCO 由两个相同的电感电容电路 (LC) 压控振荡器 (VCO) 组成，其中具有 180° 相移的二次谐波从一个核心 VCO 注入到另一个核心 VCO 的尾电流源的栅极VCO 通过耦合电容。使用高幅度的二次谐波将尾部从反相切换到累加，因此减少了闪烁噪声。此外，由于使用了无损耗和无噪声耦合元件，即耦合电容器，并且由于存在固有的高通滤波器，所提出的 LC-QVCO 具有良好的相位噪声性能。

发现

引入的技术是在商用 0.18 µm 射频互补金属氧化物半导体 (RF-CMOS) 技术中设计和模拟的，并且实现了接近相位噪声 10 dB 的改进（与传统方法相比）。仿真结果表明，在偏离 5.76 GHz 中心频率 3 MHz 处，所提出的 QVCO 的相位噪声为 -130.3 dBc/Hz，而从 0.9-V 电源汲取的总直流 (DC) 电流为 4.25 mA（图优点 = -190.2 dBc）。Monte Carlo 仿真结果表明，该电路的品质因数呈高斯分布，平均值和标准偏差分别为-189.97 dBc 和0.183。

原创性/价值

该技术提供了一种新的简单但有效的超谐波耦合和噪声整形方法，该方法通过切换具有 2 ω0（振荡频率的二次谐波）的尾部晶体管来降低超谐波多相 VCO 的接近相位噪声。没有额外的设备，如消耗面积的变压器或额外的耗电振荡器用于耦合。