Thermal macromodelling of integrated circuits

Most of the existing macromodels for integrated circuits (ICs) today have characteristics that are independent of temperature. The macromodels usually assume the IC operates at a fixed temperature, frequently taken to be a defined nominal temperature representing room temperature. This is in spite of the fact that IC characteristics are strongly dependent on the temperature of the device. In this paper, we discuss a methodology for thermal macromodelling of ICs to take into account the temperature dependence of the IC being modelled. The methodology may be used to convert a macromodel that models no thermal effects into one that models both thermal and electrothermal effects. The methodology is applied to a positive voltage regulator and is implemented in the circuit simulator PSpice.     

基于回转窑表面的红外双波段测温方法研究

回转窑是水泥熟料生产中的重要煅烧设备。在生产过程中,需要通过对回转窑的表面温度进行测量来监测窑体内部的生产状态。传统方法使用单波段红外测温对回转窑的表面温度进行监测,但是这种方法的测温精度不高,无法获取准确的测温数据。为了提高回转窑表面测温精度,提出了一种红外双波段测温方法。首先对传统的回转窑测温方法进行了理论分析,包括影响测温的几种主要因素;然后介绍了双波段测温原理,并推导出了基于回转窑的双波段测温模型;最后对其进行了实验验证。结果表明,与传统的单波段测温方法相比,本文方法在温度测量方面具有更高的精度。     

Numerical simulation of magnetic induction heating of tumors with ferromagnetic seed implants

Calculations based on the bioheat transfer equation have been carried out to determine the temperature distributions to be expected from the use of inductively heated ferromagnetic implants to heat deep-seated tumors. Two types of ferromagnetic implants are considered: constant power seeds, for example, those constructed from Type 430 stainless steel; and constant temperature seeds which pass through a Curie transition to the nonmagnetic state at a specified temperature. The temperature distributions are studied as a function of the size of the implant array, its geometrical relationship to the tumor, the density of implants within the array, and the blood perfusion characteristics of the tumor and its surrounding normal tissue. Two tumor models are considered: a uniformly perfused model which is indistinguishable from the surrounding normal tissue, and an annular perfusion model with a necrotic core surrounded by intermediately and highly perfused shells. Temperature distributions are considered acceptable if the minimum temperature in the tumor is greater than 42°C and the maximum temperature does not exceed a maximum allowable value (either 48 or 60°C). The results of over 200 combinations of the above parameters are presented in a compact format. General conclusions drawn are that the tumor should lie entirely within the implanted array if the tumor periphery is to be heated adequately, and that the constant temperature seeds, which are self-regulating in temperature, give better tumor temperature distributions.     

基于红外通信的温度采集系统设计

温度检测在科学研究和社会生活中极为重要。随着科学技术的不断发展,温度检测需求也日趋增加。为了解决生物及化学实验中密闭、高温、高压、粉尘等特殊环境下不宜直接进行温度检测或者只能采取有线形式进行温度检测的问题,设计了一种基于红外通信的温度采集系统。该系统将DS18B20传感器作为温度传感器,用51单片机采集温度后从串口输出,再通过调制38 kHz载波形成红外信号;接收端采用VS1838B一体化红外接收头接收温度信号,最后由LCD1602器件显示温度信息。测试结果表明,本文系统能够实现无接触式环境温度检测,满足实验要求。     

基于拉曼激光雷达的南京上空大气温度廓线观测

介绍了综合使用瑞利、拉曼、米散射三种技术的激光雷达的基本结构与拉曼散射温度反演原理。对其中的拉曼回波信号进行了背景噪声扣除、滑动平均和小波变换降噪,在此基础上分析了气溶胶对拉曼激光雷达温度廓线反演的影响。利用上述激光雷达信号处理方法对南京上空的温度廓线进行观测,反演了2010年11月19日18时53分至19时35分连续观测的数据。反演的温度廓线表明,观测开始至观测结束,5.5 km处的温度变化为2 K的波动变化;对2010年11月整月的观测数据进行分析处理,得到11月份上中下三旬的平均温度廓线。在10 km高度处,下旬温度比上旬温度低4 K,随着入冬的进程,低空段的大气温度递减率有明显增大的趋势;11月的月平均温度在5~10 km处低于模式值4 K左右,并且两者几乎平行,说明11月份5~10 km各高度温度比模式均低4 K左右。     

The temperature dependence of Nd/sup 3+/ doped solid-state lasers

The temperature-dependent performance for long-pulse and Q-switched Nd/sup 3+/ doped solid-state lasers are analyzed. Over a wide temperature range, it is shown that the output energy for the long-pulse laser decreases with increasing temperature as does that of the actively Q-switched laser when pumped to the same level of inversion at all temperatures. Conversely, when such lasers are pumped to the amplified spontaneous emission limit at each temperature or when the laser is passively Q-switched, the output energy increases with temperature. These temperature dependencies are analytically predicted and are compared to experimental results collected on various Nd:YAG and Cr:Nd:GSGG laser systems. The laser performance data and the model developed are shown to be in close agreement when using values for the stimulated-emission cross section and its temperature derivative obtained in separate spectroscopic measurements.     

Instantaneous temperature profiles inside semiconductor power devices: Part I

Under electrical load the crystal temperature inside a semiconductor power device changes substantially both in space and in time. Its measurement with good resolution in temperature, in time as well as in space, was attempted by detecting the thermal radiation emitted from an operational semiconductor device that was thick enough to be opaque to thermal infrared. A cooled InSb detector is followed by an amplifier allowing for a tradeoff between time resolution (the overall time constant varied from 0.5 to 86 µs) and temperature resolution, such that their product remained constant. For temperature fields periodic in time, sampling methods and signal averaging are applied which further improve temperature resolution with time and space resolution remaining unchanged. A large improvement in speed of response with respect to conventional methods results. For a fixed surface point the time dependence of temperature is obtained. Fixing the observation window in time leads to profiles of instantaneous temperature across a selected line of the exposed semiconductor which are in good agreement with those predicted by a recent theoretical model. In Part I the case of thick slices is treated. The extension to thin slices which are transparent to thermal infrared are treated in Part II.     

单个脉冲作用下熔融石英的温度和热应力研究

理论研究单个激光脉冲作用光学材料的温度和热应力分布模型,根据脉冲特征,分别建立适用于短脉冲和长脉冲的温度分布模型;进一步建立单个脉冲作用下的热应力模型。以熔融石英为例数值计算和分析了单个脉冲作用下的温度和热应力分布。研究结果表明,如果只求解单脉冲结束时的温度分布,长脉冲和短脉冲模型计算结果一致。单个激光脉冲辐照熔融石英,材料温度升高,如果温度达到材料融化或汽化温度,将导致材料的熔融汽化破坏,另一方面,在焦点区域温升不均匀,将导致热应力产生,如果热应力达到材料的力学破坏阈值,将诱导材料的热应力损伤。     

Effect of Temperature on Device Admittance of GaAs and Si IMPATT Diodes

The effect of temperature on the small-signal admittance of IMPATT diodes with uniformly doped and high-low doped (Read) structures is investigated experimentafly and theoretically. Small-signal admittance characteristics of X-band Si p+-n-n+, GaAs M-n-n+ (Schottky-uniform), and GaAs M-n+-n-n+ (Schottky-Read) IMPATT diodes are measured at various junction temperatures for different dc current levels. Small-signal analysis is performed on GaAs IMPATT diodes of uniformly doped and high-low doped structures, and the calculated results on temperature dependence of the device admittance are compared with the experimental results. Reasonable agreement is found between theory and experiment. It is shown that GaAs IMPATT diodes are superior to Si diodes in admittance temperature characteristics and that the uniformly doped structure has a small admittance temperature coefficient in magnitude, compared to the high-low doped structure. It is also shown by calculation that the admittance temperature coefficient of a punch-through diode is small in magnitude, compared to that of a non-punch-through diode.     

A Digital Frequency-to-Temperature Converter For Use in Radio Telemetry Systems in Which Temperature is Transmitted Proportional to a Subcarrier Frequency

A digital frequency-to-temperature converter was designed to demodulate the signal from a surgically implanted temperature telemetry transmitter. In addition to providing a digital readout of time and temperature, it provides a signal for analog recording. It win update the time and temperature readout only when two successive frequency measurements of the signal are the same, thus eliminating nearly all erroneous temperature data caused by noise. These time and temperature data are provided in binary coded decimal (BCD) form so that they can be recorded as reliable data in digital form for eventual computer processing. Although the unit is somewhat complex, a primary feature of its design is that a person with no electronics training can easily calibrate and use it by switching three sets of binary numbers, associated with the particular temperature transmitter in use, into the machine.     

裸光纤Bragg光栅的温度传感特性研究

从理论上分析了光纤Bragg光栅的温度传感原理,并通过实验对裸光纤Bragg光栅的常温温度特性进行了测试。实验结果与理论分析基本一致,证明裸光纤Bragg光栅在常温下的中心波长与温度变化呈良好的线性关系,为其用作温度传感器提供了理论和实验依据。最后,指出了光纤Bragg光栅温度传感器在实际工程化应用中所需要解决的问题。     

温度对碲镉汞光伏芯片I-V特性的影响

对室温工作的短波碲镉汞光伏芯片进行了步进温度烘烤实验。烘烤温度从60 ℃开始，步长为5 ℃，到120 ℃结束，每个温度下的烘烤时间一般为24 h。实验结果显示当烘烤温度达到95 ℃以上时，I-V测试结果中反偏部分的电流有明显增大。通过理论分析得到扩散电流和产生复合电流是实验芯片的主要电流机制；较高温度的烘烤在势垒区内产生大量的缺陷，从而降低芯片的少子寿命，使扩散电流增大；同时芯片表面钝化层内的缺陷数目也在温度作用下增加，引起芯片表面复合速度增加。     

用脉冲激光沉积方法制备的ZnO薄膜的结构及光致发光特性

在从室温到800℃的温度范围内,用脉冲激光沉积方法在Al₂O₃（0001）衬底上制备了ZnO薄膜。采用X射线衍射仪、原子力显微镜以及荧光光谱仪分别研究了衬底温度对ZnO薄膜表面形貌、结晶质量和光致发光特性的影响。X射线衍射仪和原子力显微镜的结果表明,当衬底温度从室温升高到400℃时,ZnO薄膜的结构及结晶质量逐渐提高,而当衬底温度超过400℃时,其结构和结晶质量变差;在400℃下生长的ZnO薄膜具有最佳的表面形貌和结晶质量。室温光致发光的测量结果表明,400℃下生长的ZnO薄膜的紫外发光强度最强,且发光波长最短（386 nm）。     

微波辐照猪肉透热深度影响因素和表面变化

生物组织吸收微波辐照的影响因素及微波辐照效率是临床上进行体外辐照治疗时需要考虑的重要问题之一。以猪肉样本块为研究对象,用频率为2450 MHz 的微波,通过控制辐照的3 个变量(时间、功率、距离),分别探测了表层、透热最深层的温度和微观组织形貌变化。实验结果表明:增大辐照功率提升上表面温度效果最明显;根据不同深度位置的温度变化曲线,当上表面达到一定温度后才产生透热深度;从理论上解释了由于极化和弛豫现象而使上表面温度影响透热深度的原因,并由热传导方程的推导公式,验证了控制辐照影响上表面温度能够间接影响透热深度的实验结果,为微波辐照热疗中温度控制的进一步研究提供基础。     

SMT回流焊温度测试仪的设计

在表面组装技术中，炉温测试对于检测和监控回流焊质量是极其重要的，回流焊温度测试仪就是检测温度变化曲线的设备。本文设计的回流焊温度测试仪由现场单片机控制的测试系统和上位微机组成。现场单片机控制的测试系统对温度进行采集和处理，并通过串口发送给微机，由微机实现数据分析、曲线显示和打印。实验结果表明，该测试仪能够准确地测出回流焊温度。     

GaAs基长波长量子点激光器增益和阈值电流密度的理论分析

基于谐振子模型的量子点能级,计算了包括和排除激子影响时多能级的增益谱.考虑了低温时非平衡载流子分布.得出了较宽温度范围内阈值电流密度的变化,包括负温度及振荡温度效应.研究了垂直层叠和p型掺杂对量子点激光器性能的改善,并讨论了获得极小阈值电流密度时的最佳量子点密度.     

薄膜全耗尽SOI CMOS电路高温特性模拟和结构优化

在300～600K温度范围内,利用ISE TCAD模拟软件对全耗尽SOI电路的温度特性进行了模拟分析,得到了较全面的SOI CMOS倒相器静态特性和瞬态特性,并提出了一种改进的AlN-DSOI结构.结果显示,SOI CMOS电路的阈值电压对温度较为敏感,随着温度的升高,输出特性衰退明显.瞬态模拟也表明电路的速度和功耗受外界环境温度的影响较大.改进后的AlN-DSOI结构在有效缓解SOI结构热效应和浮体效应的基础上,显著提高了电路的速度和驱动能力.     

Two-dimensional tensor temperature extension of the hydrodynamicmodel and its applications

The fundamental assumption that is made in most hydrodynamic simulation programs is the scalar nature of the temperature. In this paper we examine this assumption and present a model that takes into account the full tensorial nature of the temperature. The results show good agreement with 1-D Monte Carlo calculations for a ballistic diode and reproduce some of the qualitative features of 2-D Monte Carlo results for MOSFETs. In terms of terminal currents, 2-D tensor temperature simulation of BJTs shows only small differences when compared with results from scalar temperature formulation. For MOSFETs the differences are up to 15%. Internal distribution of temperature in MOSFETs shows some interesting properties that cannot be reproduced by the scalar temperature hydrodynamic model. The details of the physical models and transport coefficients used are also described     

Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates

Thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non‐covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels’ physico‐chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties.     

Semiconductor package qualification based on the swelling temperature

Currently, as semiconductor packages are becoming increasing smaller with improved performances, many are being constructed using stacked structures. However, these types of packages are not easy to qualify owing to the potential swelling of the stacked layers. In this paper, we propose a new method for reliability testing that directly measures the adhesion strength using the swelling temperature to assess the reliability of the package. The swelling temperature is the temperature at which a peel-off occurs between the layers. The advantage of the proposed method in comparison with the traditional reliability testing methods is that the proposed method enables a quick assessment of the product reliability. Through testing and actual case studies, we found that the product reliability qualification can be determined solely by measuring the swelling temperature.