功率器件的散热设计方法

在模拟电路设计过程中难免会使用功率器件,如何处理和解决这些功率器件散热问题对于电路设计师来说非常重要,因为这些功率器件的工作温度将直接影响到整个电路的工作稳定性和安全性,文中首先介绍了功率器件的热性能指标,并根据作者的实际工作经验,介绍了功率器件的散热设计方法.     

功率器件热设计及散热计算

本文介绍了功率器件的热性能参数,并根据实际工作经验,阐述了功率器件的热设计方法和散热器的合理选择。     

用显微红外热成像技术分析功率器件可靠性

利用显微红外热成像技术对功率器件进行热可靠性分析。先从理论上阐述了显微红外热成像技术的原理,进而尝试利用该技术进行微波功率器件可靠性筛选工作,通过分析获取了显微红外图像中的温度分布和峰值温度,大大提高了器件可靠性筛选工作的准确性。在功率器件失效分析方面,利用显微红外热成像技术对发生失效的器件进行热成像和分析,通过定位失效点找到器件发生失效的原因。另外,还利用该技术来验证器件热设计的成功与否,通过显微红外热成像获取的温度信息如峰值温度、温度分布等来判断器件的热设计是否符合要求,在实际的器件设计过程中起到了良好的效果。     

三维功率MOSFET器件的热可靠性设计

基于三维集成技术的功率MOSFET器件,在发热量大和散热难的双重压力下,热可靠性设计凸显得尤为重要。文中采用硅通孔散热方式,在三维功率器件内嵌入大量的散热硅通孔,以降低芯片内热阻,疏导功率器件产生的热量,保证器件有源区结温低于极限安全结温,可有效提高芯片的热可靠性。以100 V,60 A的功率VDMOS器件为研究对象,以提高芯片的热可靠性为目的,合理设计和充分优化了三维功率MOSFET器件的版图和散热硅通孔的布局。基于多物理场分析软件开展了大量的热可靠性仿真分析工作,并流片验证了设计的正确性。     

基于ANSYS的IGBT热模拟与分析

根据IGBT的基本结构和工作原理,建立了一种新的IGBT三维热模型.运用基于有限元法的分析软件ANSYS,对功率分别为0.5W,1.0W,1.5W,2.0W条件下的器件热分布进行模拟分析.结果表明,热耦合加剧了器件的自升温,且功率越大,影响越明显.另外,考虑了热导率随温度变化情况下的器件热模拟结果显示:在相同的功率(1W)条件下,器件最高温升高4.8K.由模拟结果得到的热阻与红外实测结果基本一致.     

半导体功率器件热膨胀特性的全息干涉测试

采用全息干涉技术对半导体功率器件通电运行中的热变形进行了研究,测量了器件的离面位移分布及其弯曲挠度。通过改变功率数值或对样品的装配条件,探索功率、工作条件、夹持应力等因素对器件及芯片区域变形产生的影响;对器件的变形模式及其现象的因果关系进行了分析和讨论。     

微通道热沉标准单元制作的SEM观察

半导体激光器由于其体积小、重量轻、结构紧凑且峰值功率高而受关注,由于其结构紧凑而使焊在载片上的器件在界面产生热流峰值达1kw/cm2量级,电-光转换效率达50%～60%,这个热负载限制了器件室温工作的要求,是高功率器件运转的主要限制因素。为便于高平均功率下这些器件的运行,各种有效热沉已发展起来,大致分为两组:(1)一组激光器安装在一个热沉结构上;(2)一个激光器安装在一个单独的热沉上。由于在(1)情况下维修困难大,而选用Si微通道热沉使热阻值低于现有的冷却器,且标准制冷单元可使LD组成大的阵列,易于实现多功率、多占空比激光器组合及…     

耗散功率与环境温度对功率VDMOS热阻的影响分析

运用电学测试法,以两款不同封装类型功率VDMOS为实验对象,考察了耗散功率和环境温度对器件稳态热阻值的影响。结果表明：器件热阻值不是一个恒定不变的常量,由于电流拥挤效应,材料导热系数等条件的改变,它会随耗散功率及环境温度的增大而增大。该研究加深了对功率器件热阻理论的认识,为功率VDMOS的热特性评估提供了可靠的依据。     

安森美智能、高集成器件新产品

安森美半导体日前推出SMARTHotPlug智能、高集成器件的新产品系列,简化用于经常启动的计算机和电信系统的电路板热拔插功率保护。这些强化可靠的新器件,能消除因母线干扰、过载或短路引起的高成本停机时间,适合于分布功率系统、高可用性服务器、磁盘阵列和热拔插应用等。安森美智能、高集成器件新产品@刘璇     

808nm连续波2000W半导体激光器垂直叠阵

为了全面提高大功率半导体激光器的性能和功率,采用双面散热技术,优化了大功率半导体激光器垂直叠阵和单bar器件的热管理和热设计,使得808nm单bar半导体激光器在连续波工作模式下的功率达到100W;808nm 20bar垂直叠阵功率达到2000 W.对微通道液体制冷大功率半导体激光器叠阵和单bar半导体激光器器件的LI...     

抗辐射加固集成稳压电源的最新设计和研究

本文探讨了降低线性集成稳压电源的功耗和提高它们的抗辐射能力的技术途径。介绍了一种新型稳压器电路,以低功耗电流放大器为其基础,改电压控制型为电流控制型,使电路在满载情况下,输入输出最小压差降到1V左右;并具有良好的启动保护功能,纹波抑制比可达70db以上;当输出电压V_o=12V时,其效率的典型值为90％。 为了尽量提高这种电路的抗辐射能力,在设计电路时就注意到了降低有源元件与无源元件的数量比,使电路设计尽量简化。并充分注意到光电流补偿单元的设置和增益裕量的限度。采用了介质隔离技术和晶体管归一化的标准设计,在工艺参数的设计中采用特殊加固晶体管的设计方法。使该电路的抗中子能力比初步加固的器件提高一倍左右,抗γ瞬时辐照能力提高二倍以上。     

Voltage stress effect on class AB power amplifier and mixed-signal sample-hold circuit

The effects of gate and drain voltage stress and breakdown location on the class AB power amplifier and mixed-signal sample-hold circuit have been studied. The soft breakdown has minor effect on the performance of the power amplifier and sample-hold circuit, while the hard breakdown at the drain side reduces the power efficiency of the class AB power amplifier and degrades the signal to noise ratio of the sample-hold circuit significantly. Also, hot electron effect reduces the linearity of the class AB power amplifier.     

Design and Development of New Digital Thermostat

The designed thermostat is based on the microcontroller featuring intelligence, programmable, environmental protection and power saving. The thermostat design is mainly composed of hardware and software design, the hardware includes the power supply circuit, temperature measurement circuit, humidity measurement circuit and backlight circuit; while the software design includes temperature measurement and compensation algorithm, moreover software flowchart is given as well. Finally the power supply circuit is simulated by the software of Pspice and the creative power stealing mode is verified by the simulation results. A target board is stuffed by hand with Pb-free electronic components and used to test hardware and debug software. Since the Pb-free components were used, power stealing mode is designed in hardware and temperature compensation algorithm is accomplished in software, and the thermostat is outstanding with its features of ＂green＂ and ＂power saving＂.     

VLSI电源网络近似电路模型研究

针对基于底层规划的电源网络分析、优化需求,提出了一种电源网络近似电路模型.根据电源网络结构特点,对其进行层次划分,并充分考虑标准单元吸纳电流的统计分布特性,建立各组成元件的电路模型.在此基础上,利用诺顿等效原理对其进行简化.实验表明,基于近似电路模型的电源网络分析结果比悲观分析要小38.75%(最差电压降)和36.04%(中心节点电压降),分析结果更为可信.     

Impact of strain on hot electron reliability of dual-band power amplifier and integrated LNA-mixer RF performances

Channel hot-electron-induced degradation on strained MOSFETs is examined experimentally. BSIM stressed model parameters are extracted from measurement and used in Cadence SpectreRF simulation to study the impact of channel hot electron stress on dual-band class-E power amplifier and integrated low-noise amplifier-mixer RF performances. Channel hot electron effect decreases power efficiency of dual-band class-E power amplifier and increases the noise figure of low-noise amplifier-mixer combined circuit.     

电源适配器能效技术进展

概述了国内外对外部电源在能效方面的要求及发展趋势,介绍了电源适配器在能效改进方面的一些技术动态,并从元器件和电路结构的改进方面,对电源适配器在能效技术上的应用进行了阐述和分析。     

Methodology of reliability enhancement for high power LED driver

The degradation of a linear-mode high power LED driver is studied. This driver is to provide constant current to LED regardless of its output voltage, but there is a minimum output voltage whereby the output current cannot be maintained as constant. Prolonged operation of the driver through relevant reliability test revealed that this minimum voltage will increase due to degradation of the output transistor in the driver, and when this minimum voltage exceeds the operating voltage of the driver, it no longer provides a constant current to the LEDs. Our investigation clearly reveals that the degradation mechanism is hot carrier injection as will be shown in this work, and hence it is inevitable. As high power LEDs have long life time, their drivers must also have equivalent lifetime so that the long life of LEDs can be leveraged in the entire luminary. One method to enhance its lifetime is to increase the hot carrier injection lifetime of the output transistor which may requires some fundamental change in the transistor structure and/or processing, and it is beyond the control of the driver designer and can be expensive also. A circuit approach is to use redundant circuit for enhancement which is common in the circuit world. Effective switch over to redundant circuit requires continuous health monitor of the primary circuit. In this work, the method to identify the health monitoring index, based on the degradation mechanism is shown, and the control circuit to detect and switch over to the redundant circuit is also designed and presented here.     

The Linear Analysis of Coaxial Helical-Groove Slow-Wave Structure

The coaxial helical-groove slow-wave structure is a new-type high power circuit. The dispersion equation of this circuit with an annular electron beam is obtained according to self-consistent field theory. The computation results of the hot dispersion equation show the relations between electron beam parameters and the small signal gain. The presented analysis will be useful for the design of the TWT with coaxial helical-groove circuit.     

Thermal Design of Electronic-Circuit Layout For Reliability

A method for laying out electronic components on back board, which minimizes the maximum temperature rise of components is presented. This avoids hot spots on the board. Sensitivity analysis is adopted for optimal placement of components on the circuit board and certain relations are derived with a view to reduce the computational effort of sensitivity analysis.