声表面波传感器检测电路的研究

针对目前声表面波(SAW)传感器检测电路的缺点,通过对SAW传感器信号的特征分析,设计了一种简单实用的SAW传感器检测电路,降低了硬件成本。该电路利用直接数字频率合成技术产生不同的频率信号,用以激励不同谐振频率的声表面波敏感元件,在间歇收发周期从SAW传感器输出信号中提取出反映被测量的频率信号,通过对该频率的测量得到被测物理量的变化。通过对SAW传感器的温度实验,获得了传感器的温度-频率特性,在较低频率(20MHz)时检测灵敏度可达1.36kHz/℃,具有较好的一致性;在较高频率(75MHz)时检测灵敏度可达2.03kHz/℃,存在一定偏差。     

一种温湿度测控电路芯片的研制

提出了一种运用混合信号的温湿度测量控制电路的设计方案。通过温湿度传感器的电阻变化来检测温湿度的变化,运用RC振荡原理,把传感器的电阻值转换为频率信号,并使用一片ROM把频率信号映射为实际的温湿度,从而实现温湿度的测量。在芯片设计中,详细考虑了如何进行综合的优化设计。芯片的温度测量范围为-20～60°C,精度为±1°C;湿度测量范围为40%RH～90%RH,精度为±10%RH。芯片测试结果表明,该电路功能正确,性能良好,各项指标均达到预定目标。     

一种大量程低误差CMOS温度传感器

温度传感器是将温度信号转换为电信号的元件。CMOS工艺制作的温度传感器具有面积小、成本低的优点,精度和工作温度范围是CMOS温度传感器最重要的两个指标。设计了一种工作温度范围为－45 ℃~125 ℃,测量精度为±1.5 ℃的温度传感器,主要包括温度传感电路和后端Σ-Δ ADC两部分,设计时采用了曲率校正、动态匹配等多重误差的校正方法。     

数字温度表集成电路DS1620

ＤＳ１６２０把温度传感器、模数转换和比较电路集成在一个电路中实现，可以０．５℃的精度对－５５～＋１２５℃之间的温度进行测量．并当温度超出指定的范围时给出报警信号，本文介绍了ＤＳ１６２０的工作原理。     

声表面波调频振荡器

论述了声表面波调频振荡器的原理及设计方法，探讨了有关电路，并制作了中心频率３８０．８ＭＨｚ的声表面波调频振荡器。当调制信号频率区ＤＣ至８００ｋＨｚ变化，幅值为２．５Ｖ时，调频频偏大于５５０ｋＨｚ；当调制信号频率小于或等于２００ｋＨｚ，幅值为１．０Ｖ时，调频非线性失真小于３．５％。振荡器经过温度补偿，温度稳定性优于±１５０ｐｐｍ（－４０℃～＋５０℃）。     

一种面向无源RFID的新型高精度温度传感器

针对目前超低功耗温度传感器误差大的问题,运用由精确比例电流源偏置的寄生衬底PNP晶体管,采用0.18 μm混合信号工艺设计了一种可集成于无源RFID标签的新型高精度温度传感器。传感器核心电路产生与绝对温度成正比的电压信号,通过新型开关电容积分器进行放大,并由改进的12位超低功耗逐次逼近模数转换器完成数字量化。仿真结果表明,单次温度转换时间为4.25 ms；在1.8 V工作电压下,平均电流为17.5 μA；在－37 ℃~91 ℃范围内,温度误差为 －0.1 ℃~0.43 ℃。     

一种具有高阶温度补偿的高精度RC振荡器设计

基于当前一些高集成度高精度应用领域时钟信号大量需求的目的，介绍了一种具有高阶温度补偿的高精度RC振荡器。文中所设计的电流源电路采用了3阶温度补偿的方法，可以有效降低电路对温度变化的敏感性，利用具有超低温度系数的电流对电容进行充放电，实现在较宽的温度范围内振荡器频率的高稳定性。仿真结果表明：在电源电压范围为2.5 V～5.5 V，温度范围为-40℃～125℃，及不同的工艺角下，输出频率精度保持在±0.25%以内。该RC振荡器具有高精度的输出频率，能够作为一些数模混合电路的时钟信号。     

基于PIC16C72的水位水温控制器的设计

为满足落水式太阳能热水器自动控制的要求,设计了一个基于PIC16C72单片机的水温水位控制器。以NTC热敏电阻作为测温传感器,用PIC16C72内置的多路8位A/D转换器把NTC热敏电阻上的压降转换为数字量实现测温。通过非对称多谐振荡器电路把水位传感器的等效电阻转换为振荡信号的频率,然后用PIC16C72内置的计数器测量频率的高低,实现对水位的测量。介绍了控制器的工作原理、完整的硬件电路和功能。该设计省去了温度测量信号调理电路、专用A/D转换和输出译码驱动芯片,具有硬件系统组成简单、可靠性好的特点。     

热激励硅谐振梁压力传感器闭环数据采集系统

利用正反馈闭环谐振原理,采用偏置交流激振、一倍频拾振的方法,设计了闭环谐振电路和相应的数据采集电路,并对该电路进行了综合调试.实验结果表明,该系统实现了该传感器频率信号的自动跟踪和信号转换,以及快速、准确采集压力数据的功能,采集频率范围为30～100kHz,频率采集精度为±1Hz,温度采集精度为0.03℃.     

新颖应用电路·实用电路集

６１９－２线温度传感器　　松下半导体公司的ＬＭ３５型温度传感器因两方面的原因获得广泛应用：其生产的输出电压直接与所测量的温度（℃）成正比以及可测量零度以下的温度。但该器件的一个缺陷就是在其标准应用电路中,要通过３线链路将其与实际测量电路连接起来。本电路可彻底克服这一缺陷。当如图所示连接ＬＭ３５时,在－５～４０℃的温度范围内,就可采用２线链路。实际上,由于所示电路采用静态电流随温度改变的变化量,因此它实际上是一个与温度有关的电流源。计算电阻器Ｒ３和Ｒ４之值,输出电压为１０ｍＶ℃－１。在精度要求高的…     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

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.