测频锁相环及数控振荡器

包含有数控振荡器的锁相环可以实时读出输入信号的频率,因此可以在连续波测速定位系统中,用来直接测量瞬时多普勒频率。提出了一种测频锁相环方案,对其稳定性和精度进行了分析,与实验结果基本一致。还说明含有数控振荡器的锁相环可以直接测量瞬时相位。最后介绍了一种数控振荡器,提出了一种简单的设计方案。     

面向高速移动通信系统的载波同步技术

针对高速移动通信系统大多普勒频偏和导频资源受限条件下的载频同步问题,提出了一种级联递进载波同步方法。首先利用数据帧首尾导频块估计与校正接收信号多普勒频率变化率;然后设计了基于多级自相关运算的高精度多普勒频偏估计模型;最后采用三阶锁相环跟踪剩余的多普勒变化率和频率偏移。仿真结果表明,该方法多普勒频率变化率校正满足载波同步需求,具有较高的多普勒频偏估计精度和较低的解调误码率。     

锁相环频率合成器的发展及应用

锁相环频率合成器在现代电子通信系统中有着广泛的应用。本文主要介绍了锁相环频率合成器的发展历程，各阶段的工作原理，并描述了一个锁相环频率合成器的应用实例。     

MC145156锁相环频率合成器的单片微机控制

频率合成器是通信、雷达、测量设备的一种基本部件。目前,已将锁相技术、娄字分频技术、超大规模集成电路技术结合起来,研制并生产了一系列大规模集成电路锁相环频率合成器(LSI PLL Frequencysynthesizer),集成电路芯片MC145156就是其中之一。单片微机与大规模集成电路锁相环频率合成器结合所组成的系统,具有频率稳定度高、频谱纯、频率变化范围宽、可选信道数目多、系统调试方便、可靠性高、成本低、体积小等特点。下面我们介绍MCS-51单片机与MC145156锁相环频率合成器所组成的系统,重点介绍MCS-51单片微机对MC145156的控制。     

测量精度达2.6°的光外差干涉仪用动态相位计

结合用于磨床加工的光外差表面粗糙度在线干涉测量仪，文中介绍了高精度动态相位计的设计与实现。依据相位测量和整数周期计数相结合的原理，不仅提高了测量精度，而且将测量范围得以扩大；利用锁相环频率跟踪的特点，实现动态测量。在工作中心频率为２ＭＨｚ应用场合下，该相位计的测量精度达２．６°（相当于３．２ｎｍ），允许测量中最大多普勒频移±２０ｋＨｚ（对应高度的变化率±８．７５×１０＾－３／ｍｓ），完全满足磨床加     

基于FPGA的激光多普勒测长仪信号处理算法研究

针对激光多普勒测长仪多普勒频率的准确提取问 题,提出了一种基于FPGA的自适应采样频率的多普勒信号 处理算法。首先通过跟踪多普勒频率实现了采样频率的自适应选择,提高了低速测量的准确 度,扩大了系统的测速 范围;结合了FFT-FS频谱细化算法和比值校正算法,有效减小了测量误差,进一步提高了 多普勒频率提取的准确度; 最终通过多组长度测量实验,验证了算法的可行性,测量结果的相对误差优于0.1%。     

变采样率技术在电磁波流速测量中的应用研究

介绍了基于电磁波的水流速度测量的基本原理一多普勒效应,分析了不同采样频率对多普勒频率分辨率、测量精度、最大可测速度以及系统实时性的影响,指出单一采样频率无法满足测量系统对测量精度、量程和嵌入式系统实时性的要求,从而提出将变采样率技术应用在测量系统中。在理论研究和仿真分析完整数倍抽取、整数倍内插和有理数倍变采样率算法之后...     

高频锁相环的可测性设计

边界扫描是数字电路常用的测试技术，基于IEEE1149．1标准的边界扫描技术对一款CMOS高频锁相环进行了可测性设计，该锁相环最高工作频率达GHz。详细讨论了最高输出频率、输出频率范围和锁定时间参数的测试方案，给出了详细的测试电路和测试方法。对应用该测试方案的锁相环电路增加测试电路前后的电路网表进行了Hspice仿真，仿真结果证明该方法能有效测量锁相环的参数，并且对原锁相环电路的功能影响很小。该测试方法可广泛用于高频锁相环的性能评测和生产测试。     

光学锁相环的研究进展

光学锁相环（OPLL）根据其锁定的两束激光间是否存在频差可分为零差光学锁相环和外差光学锁相环。主要介绍了外差光学锁相环的研究进展,它是一种通过鉴频鉴相方式使激光间的频率差保持相对稳定的偏频锁定方法。相较于其他激光偏频锁定方法,光学锁相环具有结构简单、伺服频率带宽大、频率偏置范围宽、锁定准确度高等优势,在原子相干、冷原子系统、相干功率合成以及外差干涉测量等领域都得到了越来越广泛的应用。首先介绍了激光偏频锁定的主要方法及光学锁相环的特点;其次介绍了光学锁相环的基本模型,分析了光学锁相环的误差反馈过程,并按照光学锁相环实现方法的不同详细介绍了其采用的关键技术和研究进展,对近年来光学锁相环在不同领域的应用进展做了简要介绍;最后对该方法的发展路线进行了总结和展望。     

三知杯”第二届军地大学生电子制作邀请赛获奖作品 FM调制器(A题)

本设计采用频率合成技术,通过微控制器完成对系统的智能控制。系统主要由压控式LC振荡电路、锁相环电路、AGC电路、双模高速分频器、微控制器及其外围电路、电压峰-峰值测量电路、数码显示及液晶显示模块等部分组成。通过集成芯片MC145152、MC1648、MC12022等构成的锁相环频率合成电路来提高输出频率的稳定度,实现100kHz步进可调频率输出;实时测量并控制发射载波频率、输出电压峰-峰值,并用液晶显示器显示;同时数码显示输出功率;系统还实现了频率扩展、功率放大等实用性功能。输出频率稳定度达到10-5,残波辐射指标为50dB,信噪比40dB。     

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.     

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.     

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.     

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.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.