CMOS环形压控振荡器的研究及应用
发布时间：2018-10-25 10:56
【摘要】：在CMOS集成电路中经常使用到两种类型的压控振荡器,即环形压控振荡器(VCO)和LC压控振荡器,LCVCO的Q值较高,有着较强的噪声抑制能力,但电感占用可观的芯片面积是其最大的缺点。环形VCO用CMOS纯数字工艺就能够实现,具有容易集成、调谐范围宽、占用芯片面积小等优点,但它的相位噪声要比LC VCO高出20-40dBc/Hz@1MHz,糟糕的相位噪声性能成为其致命的缺点,严重限制了它的应用,目前设计具有低相位噪声的环形VCO成为亟待解决的问题,因此本文的目的在于设计一个相位噪声性能与LC VCO相当的环形VCO。本文的主要研究内容可以归结以下几点:(1)对压控振荡器的工作原理进行深入探讨,分析和比较了几种经典结构的VCO。对引入到差分延迟单元的正反馈在提高VCO的频率、改善相位噪声性能的贡献进行了分析,对调谐环形振荡器频率的几种方式进行了分析,对VCO的功耗、相位噪声、频率、输出摆幅、线性度之间需要的折衷选择进行了讨论。(2)讨论了压控振荡器的噪声机制。首先对信号路径和控制路径上的噪声到相位噪声的转换进行了详细的讨论;接着对相位噪声常见的两种模型即Lesson模型和Hajimiri模型进行推导,并分析了这两种模型在相位噪声预测方面的优势和不足之处;最后给出了几种降低相位噪声的方法。(3)使用smic180nm CMOS工艺,设计一款频率可调范围为2-4GHz的环形压控振荡器。针对环形压控振荡器较差的噪声抑制能力,设计一个波形调整模块对延迟单元的输出节点在电平切换的过程中充放电流,提高延迟单元的切换速率,进而提高波形的振幅,改善波形上升和下降时间的对称性,最终达到降低环形压控振荡器相位噪声的目的。这也是本文最具创新之处,这个降噪措施的提出和使用是依据对Lesson模型和Hajimiri模型的讨论。最后文中还对版图设计规则和技巧进行讨论,给出VCO完整的设计版图。(4)介绍了压控振荡器的一个应用领域:时钟电路,然后对这个电路的各个模块进行结构设计和最后整体电路的设计,用来对VCO的性能进行验证。
[Abstract]:Two types of voltage-controlled oscillators are often used in CMOS integrated circuits, that is, (VCO) and LC voltage-controlled oscillators. The Q value of LCVCO is high, and the LCVCO has strong noise suppression ability. But the inductor occupies considerable chip area is its biggest shortcoming. The circular VCO can be realized by CMOS pure digital process. It has the advantages of easy integration, wide tuning range and small chip area, but its phase noise is 20-40dBc / Hz@ 1MHz higher than that of LC VCO. The poor phase noise performance becomes its fatal disadvantage. Its application is severely restricted. At present, the design of ring VCO with low phase noise becomes an urgent problem to be solved. Therefore, the purpose of this paper is to design a ring VCO. with phase noise performance comparable to that of LC VCO. The main research contents of this paper can be summarized as follows: (1) the working principle of VCO is deeply discussed, and several classical VCO. structures are analyzed and compared. The contribution of positive feedback introduced to differential delay unit in improving the frequency and phase noise performance of VCO is analyzed. Several ways of tuning ring oscillator frequency are analyzed. The power consumption, phase noise and frequency of VCO are analyzed. The tradeoff between output swing and linearity is discussed. (2) the noise mechanism of VCO is discussed. Firstly, the transformation from noise to phase noise in signal path and control path is discussed in detail, and then two common models of phase noise, namely Lesson model and Hajimiri model, are deduced. The advantages and disadvantages of these two models in phase noise prediction are analyzed. Finally, several methods to reduce phase noise are given. (3) using smic180nm CMOS process, a ring voltage-controlled oscillator with frequency adjustable range of 2-4GHz is designed. Aiming at the poor noise suppression ability of the ring voltage-controlled oscillator, a waveform adjustment module is designed to charge and discharge the output node of the delay unit in the process of level switching, so as to improve the switching rate of the delay unit and the amplitude of the waveform. Finally, the phase noise of the ring voltage controlled oscillator is reduced by improving the symmetry of the rising and falling time of the waveform. This is the most innovative part of this paper. This noise reduction measure is based on the discussion of Lesson model and Hajimiri model. Finally, the rules and skills of layout design are discussed, and the complete layout of VCO is given. (4) A field of application of VCO: clock circuit, is introduced. Then each module of this circuit is designed and the whole circuit is designed to verify the performance of VCO.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN752
[Abstract]:Two types of voltage-controlled oscillators are often used in CMOS integrated circuits, that is, (VCO) and LC voltage-controlled oscillators. The Q value of LCVCO is high, and the LCVCO has strong noise suppression ability. But the inductor occupies considerable chip area is its biggest shortcoming. The circular VCO can be realized by CMOS pure digital process. It has the advantages of easy integration, wide tuning range and small chip area, but its phase noise is 20-40dBc / Hz@ 1MHz higher than that of LC VCO. The poor phase noise performance becomes its fatal disadvantage. Its application is severely restricted. At present, the design of ring VCO with low phase noise becomes an urgent problem to be solved. Therefore, the purpose of this paper is to design a ring VCO. with phase noise performance comparable to that of LC VCO. The main research contents of this paper can be summarized as follows: (1) the working principle of VCO is deeply discussed, and several classical VCO. structures are analyzed and compared. The contribution of positive feedback introduced to differential delay unit in improving the frequency and phase noise performance of VCO is analyzed. Several ways of tuning ring oscillator frequency are analyzed. The power consumption, phase noise and frequency of VCO are analyzed. The tradeoff between output swing and linearity is discussed. (2) the noise mechanism of VCO is discussed. Firstly, the transformation from noise to phase noise in signal path and control path is discussed in detail, and then two common models of phase noise, namely Lesson model and Hajimiri model, are deduced. The advantages and disadvantages of these two models in phase noise prediction are analyzed. Finally, several methods to reduce phase noise are given. (3) using smic180nm CMOS process, a ring voltage-controlled oscillator with frequency adjustable range of 2-4GHz is designed. Aiming at the poor noise suppression ability of the ring voltage-controlled oscillator, a waveform adjustment module is designed to charge and discharge the output node of the delay unit in the process of level switching, so as to improve the switching rate of the delay unit and the amplitude of the waveform. Finally, the phase noise of the ring voltage controlled oscillator is reduced by improving the symmetry of the rising and falling time of the waveform. This is the most innovative part of this paper. This noise reduction measure is based on the discussion of Lesson model and Hajimiri model. Finally, the rules and skills of layout design are discussed, and the complete layout of VCO is given. (4) A field of application of VCO: clock circuit, is introduced. Then each module of this circuit is designed and the whole circuit is designed to verify the performance of VCO.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN752
【参考文献】
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