低相噪LC振荡器的设计与实现

发布时间：2018-06-12 07:27

本文选题：LC振荡器 + 相位噪声　；参考：《电子科技大学》2015年硕士论文

【摘要】：在众多军用和民用领域中都运用到了频率信号源,而且其运用日益广泛。在导航与雷达、卫星跟踪、宇宙通讯以及时间与频率计量等领域也被广泛应用。随着现代技术的逐步发展,市场需求开始对信号源精度的要求愈来愈严格。所以,作为振荡器作为频率源的电子系统中必不可少的重要部分,人们对其要求也精准了许多。但是振荡器的相位噪声成为限制许多电子系统性能的一个至关重要的因素,人们不得不想尽办法去改善振荡器的相位噪声来提高频率信号源的性能以达到更佳的市场需求指标。LC振荡器由于低成本,可调范围广的原因,也存在一定的市场应用。因而,在实际LC振荡器的设计与实现中,深入研究其相位噪声理论并提出改善相位噪声的办法具有十分重要的意义。本文首先从时域和频域的角度出发定义了相位噪声并实现了相位噪声在两者之间的转换。其次,介绍了国际上几种通用的相位噪声模型的优缺点,从而选择最简单最直观的相位噪声模型——李森模型作为本文低相噪研究的模型。但是经典的Leeson模型只有相位噪声与品质因数有直接关系,并没有针对相位噪声的有载品质因数和振荡电路参数之间的一个具体关系进行深入的研究。因此,本文在Leeson模型的基础上,将Razavi基于单端定义的有载品质因数推广到双口网络中得出有载品质因数与电路参数的实际表达式,这样就得到相位噪声与电路参数值定量关系。再利用MATLAB仿真得到表达式中电路参数与相位噪声的变化趋势,然后可以利用关系表达式的变化趋势指导低噪声LC振荡器的设计。考虑到片上电感的实现难度以及Q值不高得因素,我们通过改变电容参数来优化设计。本文采用ADS仿真软件以及MALTLAB进行了验证,在此基础上设计了晶体三极管的低噪声电容三点式LC振荡器。然后介绍了几种通用的相位噪声测量技术,并根据其原理以及特性分析可在不同场合采用使用的测量技术。本文中使用RS信号源分析仪对制作的LC振荡器进行相位噪声测量。实验事实证明,本文提出的从提高有载品质因数的角度出发降低相位噪声的方法是可行的,并且也验证了LC振荡器的谐振回路参数变化在一定范围内能够有效的改善LC振荡器的相位噪声性能。
[Abstract]:Frequency signal sources are widely used in many military and civil fields. It is also widely used in navigation and radar, satellite tracking, cosmic communication and time and frequency measurement. With the development of modern technology, the requirement of signal source precision becomes more and more strict. Therefore, as an essential part of the frequency source electronic system, the requirements of oscillator are much more accurate. But the phase noise of the oscillator has become a critical factor limiting the performance of many electronic systems. People have to try their best to improve the phase noise of the oscillator to improve the performance of the frequency signal source in order to achieve better market demand. The LC oscillator has some market applications because of its low cost and wide adjustable range. Therefore, in the design and implementation of the actual LC oscillator, it is very important to study the theory of phase noise and put forward the method to improve the phase noise. In this paper, the phase noise is defined from the point of view of time domain and frequency domain and the transformation of phase noise between them is realized. Secondly, the advantages and disadvantages of several common phase noise models are introduced, and the most simple and intuitive phase noise model, Li Sen model, is chosen as the model of low phase noise in this paper. However, the classical Leeson model only has a direct relationship between the phase noise and the quality factor, and there is no in-depth study on the relationship between the loaded quality factor of the phase noise and the parameters of the oscillating circuit. Therefore, on the basis of Leeson model, Razavi's loaded quality factor based on single-terminal definition is extended to the actual expression of loaded quality factor and circuit parameters in two-port network, and the quantitative relationship between phase noise and circuit parameters is obtained. The variation trend of circuit parameters and phase noise in the expression can be obtained by MATLAB simulation, and then the design of low noise LC oscillator can be guided by the changing trend of the relation expression. Considering the difficulty of the on-chip inductance and the low Q value, we optimize the design by changing the capacitance parameters. Based on ads simulation software and MATLAB, a low noise capacitor LC oscillator with low noise is designed. Then, several common phase noise measurement techniques are introduced, and the measurement techniques can be used in different situations according to their principle and characteristics. In this paper, the phase noise of the LC oscillator is measured by RS signal source analyzer. The experimental results show that the method proposed in this paper is feasible to reduce the phase noise from the point of view of improving the load quality factor. It is also proved that the LC oscillator can effectively improve the phase noise performance of the LC oscillator by changing the resonant circuit parameters in a certain range.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN752

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