缓冲器输出端相位噪声模型分析

相位噪声是振荡器的重要性能指标。近年来,研究人员在振荡器相位噪声表征方面已经做了大量的工作,在这些过程中开发出了很多不同类型的振荡器相位噪声模型。但是在这些模型中,都没有分析缓冲器噪声对振荡器相位噪声的影响。而在研究课题中,首先要对缓冲器噪声的功率谱密度函数进行数学建模,并易于将这个模型嵌入到相位噪声的非线性扰动分析模型,这样就得到了含有缓冲器噪声的振荡器相位噪声模型。     

LC振荡器相位噪声的非线性摄动分析技术

相位噪声是振荡器的重要性能指标,通过对振荡器的非线性微分方程的推导,从而引入新的参数来考虑振幅噪声和相位噪声之间的相关性同时把这些参数和振荡器的工作点联系起来。并且这些公式推导也考虑了LC谐振回路中振幅噪声和相位噪声之间的相关性。在此基础上这里研究了如何在时域状态方程下将噪声看成是对振荡输出信号的小扰动,并建立引入噪声后的随机微分方程,实现LC振荡器的相位噪声分析技术。     

低相位噪声微波振荡器设计

针对Ka和Ku波段上、下变频装置对微波振荡器低相位噪声和小型化的要求,该文采用单环锁相式频率合成技术完成了微波振荡器的设计,并对锁相环的相位噪声进行了理论计算。分析了鉴相频率、鉴相器灵敏度和环路带宽对锁相环输出相位噪声的影响,根据分析结果对微波振荡器电路参数合理选择,同时兼顾了低相位噪声与小型化的设计要求。测试结果表明,振荡器的相位噪声指标与理论计算一致,各项指标均达到要求,可满足实际工程应用。     

光电振荡器的相位噪声特性

与传统的微波振荡器相比,光电振荡器利用光纤储能,能够产生低相位噪声的微波信号.论述了光电振荡器的特点、基本结构和工作原理,推导了相位噪声的表达式,对其特性进行了理论研究,并构建了光电振荡器的实验.理论分析表明,光纤延时、激光器的相对强度噪声以及微波放大器的噪声系数会影响光电振荡器的相位噪声,为减小相位噪声提供了理论依据.实验测量了3种光纤延时下的相位噪声,并与理论分析的结果进行了对比,证明了理论分析的正确性.     

振荡器时变相位噪声分析技术研究进展

介绍了两种射频振荡器的时变相位噪声模型:Demir&Mehrotra的非线性扰动模型和Hajimiri&Lee的时变相位噪声模型。对一个简单的非线性电导LC振荡器,分别建立了这两种模型,并指出了两种模型的联系和区别。讨论了两种模型的计算方法,介绍了在EDA软件HSpice和SpectreRF下,以及频域中相位噪声的计算问题。最后,进一步讨论了时变相位噪声,指出相位噪声分析的难点和未来的发展方向。     

基于随机非线性微分方程的振荡器相位噪声研究

根据振荡器电路的时变非线性特性 ,运用一种通用的相位噪声理论 ,通过对噪声源随机过程建模 ,求解具有严格数学意义的随机非线性微分方程 ,得到一个常数 c来描述时间抖动和频谱扩散。分别用基于随机非线性微分方程和线性时变的方法求解 ,结果表明线性时变得到的相位噪声频谱在基频附近分布的能量之和超过载波能量 ,在物理意义上有一定不足 ;而文中的相位噪声分析结果表明相位噪声只改变能量的分布并不能使能量显著增加 ,得到的结果为设计电路时减少相位噪声影响提供了思路。     

不同类型噪声作用下振荡器的相位噪声分析

相位噪声是振荡器最重要的性能指标.文中从描述振荡器的非线性微分方程出发,提出将噪声作为非线性微分方程的一项,通过建立随机非线性微分方程来分析振荡器的相位噪声,为振荡器的相位噪声提出了一种新的分析方法.用这种方法,在相同强度下,针对白噪声分别为加性和乘性的情形,分析其产生的相位噪声,得出了乘性噪声产生的相位噪声远大于加性噪声所产生的相位噪声的结论.     

一种低相位噪声CMOS晶体振荡器的设计

运用小信号等效模型和负阻分析法,对晶体振荡器的起振条件进行分析,并用Matlab进行了仿真验证。采用TSMC 0.18μm CMOS工艺,设计了一种基于Pierce三点式振荡器结构的14MHz晶体振荡电路。提出了一种新的幅度控制电路,提高了振荡器相位噪声性能,并降低了功耗。仿真结果表明,振荡器的相位噪声达到-129.5dBc/Hz@1kHz和-143.658dBc/Hz@10kHz,具有优良的低相位噪声特性。     

激光器对光电振荡器相位噪声的影响

为了改善光电振荡器相位噪声特性、提高光电振荡器性能,采用理论分析和实验验证的方法,研究了激光器线宽、光功率与光电振荡器相位噪声之间的关系.测试了激光器在功率相等、线宽不等情况下,光电振荡器所产生的微波信号的频谱特性和相位噪声特性;测试了给定线宽激光器在不等功率情况下,所产生的微波信号的相位噪声特性.结果表明,激光器线宽越窄、光功率越大,光电振荡器产生微波信号的频谱特性和相位噪声特性就越好;在频偏1kHz以外,相位噪声受激光器线宽影响较小,受光功率影响较大.这一结果对改善光电振荡器相位噪声有一定的帮助.     

基于CST与ADS的介质谐振振荡器的设计

分析了介质谐振振荡器的起振和稳频的原理,研究了一种低相位噪声的介质谐振振荡器的设计方法。以X波段为例,利用CST Microwave Studio 2010软件仿真了微带线与介质谐振器耦合的模型,将仿真得到的结果导入S2P文件中。再利用Agilent ADS 2011软件仿真介质谐振振荡器的完整电路,采用S参数仿真和谐波仿真分析等方法设计介质谐振振荡器,结合理论分析,调整和修改实验电路的参数值,使模型达到最好的优化结果。最后通过测试验证仿真结果。采用NEC公司的2SC5508芯片作为放大器,得出微波振荡器的输出频率为10.6 GHz,输出功率为5.19 dBm和较低的相位噪声,其在偏离中心频率10 kHz处小于-121 dBc/Hz。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.