一种新的DC-DC混合电源寿命预计方法

随着国产DC-DC混合电源产品的快速发展,其寿命越来越长,如何快速、准确地评价产品的寿命成为一项十分重要且紧迫的问题。瓷介电容和厚膜电阻是DC-DC混合电源中最容易发生失效的部位,是影响DC-DC混合电源寿命的关键元器件。通过对瓷介电容和厚膜电阻进行加速寿命试验,得到实际的失效率,进而通过可靠性预计的方法,获得DC-DC混合电源准确的寿命信息。     

浅谈数字频率合成器的组成及检修

频率合成器的用途很广,在现代通信领域和电视机、收音机中,为接收系统提供多种本机振荡信号源,同时收、发信机内所需要的一些辅助频率也将由频率合成器提供。总之频率合成器已被广泛地应用于通信、遥控、遥测、仪表、家电等设备之中。目前新型通信设备使用的频率合成器均为集成数字环频率合成器,下面就介绍这类频率合成器的组成及检修。一、微处理器控制的集成数字环频率合成器的组成微处理器控制的集成数字环频率合成器是指频率合成器的数字环部分由一块集成电路代替,此集成电路受微处理器控制,与外围的滤     

数字频率合成器的原理与实现

现代高速信息处理系统需要具备稳定精确的定时基准。系统设计人员长期以来依赖的是晶体振荡器的精度和稳定性。但是，由于系统频率的提晨以及市场竞争的压力，促使设计人员充分利用集成数字频率合成器的诸多优点，以缩短产品的开发周期。本文回顾了集成频率合成器的基本工作方式，使用MicrosoftExcel解释和举例说明了与它们的使用相关的频率计算方法。晶体振荡器晶体振荡器的最大好处在于通过对振荡器“心脏”石英晶体元件进行微调就能达到良好的频率精度。遗憾的是，由于这种微调是一种机械过程，晶体生产厂家为了实现标准的批量生产，已…     

一种大功率厚膜混合集成DC/DC变换器设计

现有厚膜混合集成DC/DC变换器的最大输出功率仅为150 W,针对输出功率无法满足工程使用需求的问题,开展大功率厚膜混合集成DC/DC变换器技术研究。采用带次级同步整流的移相全桥拓扑结构,详细阐述了反馈控制电路、磁隔离驱动电路、同步整流控制电路等设计关键点的实现方式。研制了一款500 W厚膜混合集成DC/DC变换器试验样机,将厚膜混合集成DC/DC变换器的最大输出功率由150 W提升至500 W,最高功率密度由100 W/in³提升至167 W/in³,试验结果验证了整体方案的可行性。     

厚膜混合集成无线话筒

最近上海无线电六厂利用厚膜混合集成技术试制成功微型无线话筒厚膜电路.在设计中,采用厚膜混合集成新技术、新工艺,将二十三只元器件组装在一块9×20(毫米)的氧化铝陶瓷基片上.在有源器件的组装方法上采用管芯直接烧结等新工艺,有效地提高了集成度和可靠性.电阻材料采用高稳定性的钌系厚膜浆料,     

H—W_J~Y型厚膜稳压电源的性能和应用

<正> 我厂设计、生产的H-W_J~Y型系列厚膜混合集成稳压电源是厚膜混合集成电路的典型产品之一。在国内最先采用厚膜功率集成技术和工艺,应用于通用性很广泛的直流稳压电源之中,因而可以使得原来由分立元器     

数字电视多频率射频信号源系统射频电路设计

本文介绍了使用混合信号控制器控制直接数字频率合成器(DDS)实现四个频率信号源并对输出信号进行连续控制和脉冲调制的方法,使用了通用可编程逻辑阵列实现对控制脉冲进行逻辑组合,实现了对射频功率的关断和开通,并且与外部的连锁信号进行连锁控制。本文中所使用的方法和程序经过试验和调试,均在产品的初样中获得了验证,达到了预期的效果。     

接口混合集成电路长期工作寿命预计及验证

寿命试验常被用来评估集成电路等半导体器件的可靠性,为了节约试验时间,常采用加速寿命试验方法去评估集成电路产品的工作寿命。采用基于可靠性手册中器件失效率历史数据和基于失效物理模型两种方法对接口混合集成电路的长期工作寿命进行了预计及验证。首先,通过接口混合集成电路产品多批次寿命可靠性试验的历史数据计算出了电路工作寿命;然后,基于可靠性手册中器件失效率的历史数据、模型及其使用特性要素计算出产品的工作寿命。结果表明,两者较为接近;从而证明该类混合集成电路在加速寿命试验数据不够的情况下,采用基于可靠性手册中器件失效率数据对其进行寿命预测是可行的,为接口混合集成电路长期工作寿命评估提供了一定的参考。     

基于HIP4081的厚膜H桥电机驱动电路设计

为了实现小体积、高可靠的电机驱动与控制,利用HIP4081专用芯片和ALN厚膜混合集成技术,设计一种基于HIP4081的厚膜H桥电机驱动电路,完成了H桥式驱动电路对电机双向转动和调速的控制.经实际应用,该电路不仅安全可靠地实现了电机的双向转动和调速功能,且产品体积小,导热性能好,效率高;还能在恶劣的使用环境下安全工作,提高了驱动电路和系统的可靠性,适合军、民两用.     

宇航用高可靠性频率合成器的设计

频率合成器是雷达设备的关键组成部分,该文对一种宇航用高可靠性频率合成器的方案进行了分析,着重对从设计上提高频率合成器的可靠性进行了介绍。本方案采用了锁相环方式,产生Ku波段输出信号,经验证,信号频率源准确度≤1×10-7,在Ku波段输出信号相位噪声可达-84 dBc/Hz@1 kHz。按应力法预计,工作时间内可靠度指标满足0.999 66的要求。     

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.