宽范围环形压控振荡器的设计

发布时间：2018-08-08 12:46

【摘要】：压控振荡器(Voltage-Controlled Oscillator, VCO)是一种通过控制电压改变输出信号频率的振荡器,被广泛地应用于高速串行数据通信、时钟源、数据收发等相关领域。压控振荡器最大的优点是能提供稳定、精确的信号源,而调谐范围和相位噪声性能决定了振荡器能否得到高性能的性能指标。随着4G网络的快速发展,高频、宽带的VCO在无线通信设备的地位变的越来越重要。在传统的CMOS工艺下,设计者常常会选用经典的LC电路结构来设计振荡器,这样不仅会增加工艺的压力,而且还会极大的影响芯片的集成度,从而增加设计成本。所以,在传统CMOS工艺的前提下研究高频、宽带的环形VCO显得意义重大。本文开始从三个方面介绍了VCO。分别是VCO的研究背景、意义和发展现状；然后又从振荡器的工作原理、常用分类、以及相位噪声的理论基础和典型模型出发,进一步阐述了振荡器的内部结构。振荡器的工作原理本文详细阐述了负反馈理论,并从起振,平衡,稳定三个方面解释了振荡器正常工作所要满足的条件。振荡器的常用分类包括晶体振荡器、阻容振荡器、LC振荡器等。振荡器的相位理论基础指出对于一个理想的振荡器,在受外界噪声干扰时,正弦信号的振幅和相位都会受到微小的影响。相位噪声的典型模型主要分为非时变模型和时变模型；其次研究了VCO的数学模型、压控振荡器的主要性能指标以及实现宽范围调谐的三种方法。压控振荡器的主要性能指标包括：中心频率、电源电压、调节范围、调节线性度等。实现宽带调谐的三种方法包括电容切换方式、变电感方式和多个窄带VCO切换方式；最后详细阐述了本设计的系统框图、比较器中运放的设计方法、开关电路的实现方式以及延时单元的设计理念,并在Cadence平台下对部分核心子电路及整体电路进行仿真验证。本文所设计的宽带环形VCO采用的是SMIC0.18um CMOS工艺,最终设计出的VCO输出的频率调谐范围为1.468GHz～10.13GHz;当频率在5GHz时,在10KHz频偏处的相位噪声为-23.55dBc/Hz,在100KHz频偏处的相位噪声为-51.91dBc/Hz,在1MHz频偏处的相位噪声为-80.27dBc/Hz。
[Abstract]:Voltage controlled oscillator (Voltage-Controlled Oscillator, VCO) is a kind of oscillator which can change the frequency of output signal by controlling voltage. It is widely used in high speed serial data communication, clock source, data transceiver and other related fields. The biggest advantage of VCO is that it can provide stable and accurate signal source, and the tuning range and phase noise performance determine whether the oscillator can get high performance index. With the rapid development of 4G network, the position of high frequency, broadband VCO in wireless communication equipment becomes more and more important. In the traditional CMOS process, the designers often choose the classical LC circuit structure to design the oscillator, which will not only increase the pressure of the process, but also greatly affect the integration of the chip, thus increasing the design cost. Therefore, it is of great significance to study high frequency and wide band ring VCO under the premise of traditional CMOS technology. This article begins with the introduction of VCO. in three aspects. The research background, significance and development status of VCO are respectively, and then the internal structure of the oscillator is further elaborated from the working principle, common classification, theoretical basis and typical model of phase noise. In this paper, the theory of negative feedback is described in detail, and the conditions for the oscillator to work normally are explained from three aspects: starting, balancing and stabilizing. The common categories of oscillators include crystal oscillators, resistive and capacitive oscillators and LC oscillators. The phase theory of the oscillator indicates that for an ideal oscillator, the amplitude and phase of sinusoidal signal will be slightly affected by external noise interference. The typical model of phase noise is mainly divided into time-varying model and time-varying model. Secondly, the mathematical model of VCO, the main performance index of VCO and three methods to realize wide range tuning are studied. The main performance parameters of VCO include: central frequency, power supply voltage, adjustment range, adjusting linearity, etc. The three methods to realize broadband tuning include capacitive switching, variable inductance and multiple narrowband VCO switching. Finally, the system block diagram of this design and the design method of operational amplifier in comparator are described in detail. The realization mode of switch circuit and the design idea of delay unit are discussed, and some core sub-circuits and whole circuits are simulated and verified under Cadence platform. The wideband ring VCO designed in this paper adopts the SMIC0.18um CMOS process, and the frequency tuning range of the designed VCO output is 1.468 GHz / 10. 13 GHz when the frequency is at 5GHz, The phase noise at the 10KHz frequency offset is -23.55dBc / Hz. at the 100KHz frequency offset the phase noise is -51.91dBc / Hz, and the phase noise at the 1MHz offset is -80.27dBc / Hz.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN752

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