微波功率晶体管发射极不均匀镇流电阻的设计研究

近十年来,由于卫星通讯、相控阵雷达、电子对抗等军事电子学的高度发展,对微波功率晶体管可靠性提出越来越高的要求,器件工作寿命往往要求十年、廿年以上。 据阿列尼乌斯(Arrhenins)方程,可知器件的失效率随着结温的升高,呈指数的上升,一般认为硅器件结温每降低10℃,工作寿命可提高一倍。此外,降低结温尚可以提高器件在宽脉冲工作期间输出功率的下降,改善功率增益和效率。所以千方百计降低结温以提高功率器件的可靠性,提高输出功率和效率是当前功率器件主要研究课题。而微波功率晶体管为许多有源区并联而成,因此降低结温首先要防止热斑出现,保证电流均匀分布。实现这一目的的有力措施是采用发射极镇流电阻技术。     

大功率白光LED封装技术对器件寿命的影响

通过功率LED器件封装工艺技术的改进来降低芯片结温,从而减缓器件光衰速率,延长其预期的工作寿命时间。对用于封装的关键原材料的选取进行了对比实验,指出了采用纳米级材料改进导热可降低热阻,论述了正确选用混胶材料和工艺,可以减缓器件光衰速率,达到在较高的环境温度条件下,器件使用寿命大于50 000 h。论述了器件芯片的结温对光、电、色性能的影响和不同结温其预期工作寿命时间也不同的关联性。     

改善晶体管稳态工作寿命试验方法的技术措施

1.引 言 晶体管稳态工作寿命试验是在给晶体管施加最大额定功率Ptotmax并在最高允许结温TJM下在规定时间内连续工作的可靠性试验项目。由此,可以了解器件在额定应力下的可靠性。国际标准、美国军用标准和我国有关标准都将其规定为必须的试验项目。本文将在分析现行试验方法所存在问题的基础,提出改善功率晶体管稳态工作寿命试验方法的技术措施——将直流连续工作改为连续脉冲工作。     

InAs/GaAs量子点激光器结温研究

对利用气源分子束外延(GSMBE)技术生长的InAs/GaAs量子点激光器的工作结温进行了研究,结温的测试是基于量子点激光器的温度升高会导致Fabry-Perot(F-P)腔的腔模移动.在20℃脉冲工作模式下,当脉冲注入电流的占空比从1%变化到准连续波(95%),InAs/GaAS量子点激光器的结温升高了23.9℃,在相同的测试条件下,商用量子阱激光器的结温仅升高了3.5℃.InAs/GaAs量子点激光器的结温比商用量子阱激光器的结温升高了6.8倍,这是影响激光器性能的一个重要参数.     

GaN HEMT微波功率管直流和射频加速寿命试验

分别选用南京电子器件研究所研制的1.25mm栅宽GaN HEMT和12mm栅宽GaN功率管,对小栅宽器件进行三温直流加速寿命试验,评估其直流工作可靠性,试验结果表明该器件在125℃沟道温度条件下工作的失效率为1.86×10-9/h;对大栅宽器件进行脉冲射频加速寿命试验,评估其射频工作可靠性,试验结果表明该器件在125℃沟道温度条件下工作的失效率小于1.02×10-7/h。     

微波晶体管可靠性预测

本报告给出了73.2～74.4所做的关于估价微波功率晶体管失效机理的结果,并给出了这些器件预期的可靠性和寿命结果。根据详细的失效分析进行了一系列加速射频寿命试验。估价了金和铝两种金属化系统器件。早期的工作是在 MSC1315和 PHI1510器件上进行的。PHI 型金金属化器件可在340℃结温下工作长达2000小时而不失效。MSC 型铝金属化器件在250℃结温下工作800小时或在310℃结温下工作10小时失效。其主要失效机理是电徙动。     

L波段硅脉冲功率管52000器件小时的脉冲射频加速寿命试验

利用红外热像显微测量峰值结温方法对L波段硅脉冲功率晶体管在脉冲射频(f=1.3 GHz,Pin=40 W,r=150μs,D=10％)和峰值结温220℃条件下进行52000器件小时的脉冲射频加速寿命试验.由此估算出该功率管在峰值结温125℃和上述RF条件下,器件失效率λ≤1.59×10-7h-1.试验分析表明,采用本试...     

驱动信号占空比对声光调Q脉冲光纤激光器输出脉冲重频的影响

搭建了声光调Q脉冲光纤激光器实验 系统,通过调节声光调制器(AOM)驱动信号的占空比,研 究了驱动信号占空比对声光调Q脉冲光纤激光器输出脉冲重频的影响。结果显 示,当AOM驱动信号频率 固定时,随着占空比的减小,输出脉冲重频依次为AOM驱动信号频率、AOM驱动信号频率的1/ 2、1/3。 实验结果表明,在声光调Q脉冲光纤激光器中,输出脉冲重频受A OM驱动信号频率和占空比的共同影响。     

功率型发光二极管的寿命与失效分析

可靠性是影响发光二极管应用的一个重要因素。对1 W大功率发光二极管分批在不同电流及不同结温下进行试验,分析了电流和结温对功率型发光二极管寿命的影响,应用应力加速模型推测在不同电流或结温条件下发光二极管的寿命,同时研究了试验过程中发光二极管的光电性能的变化,探索其失效机理,为功率型发光二极管的应用提供参考。     

高温高效率半导体激光器阵列封装结构研究

分析了热沉和陶瓷基板对背冷式封装结构半导体激光器阵列性能的影响.通过栅格化厚铜填充技术降低了复合金刚石热沉的等效电阻,并实现了热膨胀系数匹配;采用热沉和陶瓷基板嵌入焊接技术,提高了封装散热能力和稳定性.制作了间距为0.4 mm的5Bar条芯片阵列样品,在70℃热沉温度、200 A工作电流(占空比为1％)条件下进行性能测试,结果显示器件输出功率为1 065 W、电光转换效率为59.2％.在高温大电流条件下进行了 1 824 h寿命试验,器件表现出良好的可靠性.     

Dynamic Thermal Analysis of High-Power LEDs at Pulse Conditions

In this letter, the thermal evaluation of high-power LED packages at pulse conditions was reported. A theoretical calculation model was proposed based on the analogy between the thermal and electrical RC circuits. The thermal performance of LED packages driven by pulse input was calculated using the RC network extracted from transient thermal measurement. The junction temperature fluctuation band decreases with the frequency at certain duty cycles. The saturated average junction temperature rise linearly increases with the duty cycle at certain frequencies. These predictions were verified by the real-time junction temperature measurement using the peak shift method at pulse conditions. The theoretical model was found to be effective and applicable to the evaluation of the thermal performance of LEDs working at pulse conditions.     

基于脉冲式U-I 特性的高功率型LED 热学特性测试

热学特性是影响功率型LED光学和电学特性的主要因素之一,设计了一套基于脉冲式U-I特性的功率型LED热学特性测试系统,可以测试在不同结温下LED工作电流与正向电压的关系,从而获得LED的热学特性参数。该系统通过产生窄脉冲电流来驱动LED,对其峰值时的电压电流进行采样,同时控制和采集LED的热沉温度,从而获得不同温度下LED的U-I特性曲线。与其他U-I测试系统相比,文中采用了窄脉冲(1 s)工作电流,LED器件PN结区处于发热与散热的交替过程,不会造成大的热积累,大大提高了测量精度。实验中,对某功率型LED进行了测试,获得了该器件的电压、电流和结温特性曲线,并利用B样条建立该器件的U-I-T模型,进而实现了对其结温的实时在线检测。     

The performance of X-band Gunn oscillators over the temperature range 30°C to 120°C

The output power of a cavity-controlled Gunn oscillator has been measured at a frequency of 10 GHz, as a function of bias voltage over the temperature range 30°C to 120°C. The measurements were made using 500-ns pulses to avoid significant changes in-device temperature during a pulse, and at a duty cycle of 20:1 to maintain a low mean input power. The device was operated in a coaxial cavity made of invar, and temperature control effected by operating the cavity in an oven. It has been found that ranges of bias voltages exist over which power output and efficiency is extremely sensitive to temperature changes, and that, depending on the particular conditions, power output can either increase or decrease. The effect of increasing temperature has also been found to reduce the bias voltage required to obtain maximum power output and efficiency.     

50～75 MHz 1200 W脉冲功率LDMOS器件的研制

分析了工作于甚高频(VHF)频段的千瓦级横向扩散金属氧化物半导体(LDMOS)器件的输出功率、漏极效率及功率增益等关键参数在设计时应考虑的因素,在此基础上,采用0.8 μm LDMOS工艺成功研制了一款工作于VHF频段的脉冲大功率硅LDMOS场效应晶体管(LDMOSFET).设计了用于50～ 75 MHz频带的宽带匹配电路.研制的器件击穿电压为130 V.在工作电压为50 V,工作脉宽为1 ms,占空比为30％的工作条件下测试得到,器件的带内输出功率大于1 200 W,功率增益大于20 dB,漏极效率大于65％,抗驻波比大于10∶1.     

体积小重量轻的SiC微波脉冲功率晶体管

采用自主开发的工艺加工技术和设计方法,直接将两个微波SiC MESFET管芯在管壳内部进行并联,实现了器件在S波段脉冲状态下(工作频率2GHz,脉冲宽度30μs,占空比10%)输出功率大于30W、功率增益12dB、功率附加效率大于30%的性能指标。由于直接采用管芯并联结构,省略了内匹配网络,器件的体积和重量较以往的Si微波双极功率晶体管大为降低;采用高温氧化技术克服了传统MESFET工艺中PECVD介质产生较高界面态的不足,减小了器件的泄漏电流,提高了器件性能。器件的研制成功,初步显示了SiC微波脉冲功率器件在体积小、重量轻、增益高、脉冲大功率输出和制作工艺简单等方面的优势。     

Lifetime estimation for IGBT modules in wind turbine power converter system considering ambient temperature

Power semiconductors in the wind turbine power converter system suffer from two-scale thermal loadings, the fundamental frequency thermal cycling caused by the output frequency of converter and the low frequency thermal cycling due to the variation of long-term wind speed. These two-scale thermal loadings introduce different consumed lifetimes. Accurate lifetime estimation in the wind power application is desired for reliability prediction and health management. This paper adopts the Bayerer lifetime model to evaluate the consumed lifetime of power semiconductors in wind power converter systems based on a numerical junction temperature calculation method. Lifetime estimation can be improved by taking into account the ambient temperature. Studies show that fluctuations of the ambient temperature increase the consumed lifetime due to the low frequency thermal cycling, but have little effect on the consumed lifetime due to the fundamental frequency thermal cycling. Our results also show that the consumed lifetime due to fundamental frequency thermal cycling mainly falls on the high wind speed area, whereas the consumed lifetime due to low frequency thermal cycling is clustered in the area due to large low frequency junction temperature fluctuations. The resulting distribution characteristics can be used in the thermal management for reliability improvement.     

On-state voltage drop based derating/uprating on a MW converter to improve reliability

Power semiconductor devices are the most fragile components limiting reliability of power converters, where major stresses are temperature dependent parameters. Typically, the operating virtual maximum junction temperature is specified by a manufacturer for each individual device. The thermal system and operating load are designed based on this number. Online monitoring of an on-state collector–emitter voltage (υ_ce,on) and a junction temperature is necessary to ensure the design performance within a safe limit and also to make this method applicable for derating/uprating power. This paper presents the real time measurement of υ_ce,on and thereby the junction temperature estimation in high power converters. Knowing these parameters online, the maximum power capability can be detected. The operating maximum junction temperature is selected and thereby based on the operating condition the derating of power is shown for a megawatt (MW) converter. An experimental setup including online monitoring is described and the measurement of power derating is presented at the specified conditions.     

1?MHz–3.5?GHz, wide range input duty 50% output duty cycle corrector

A duty cycle corrector (DCC) is proposed in this paper. By directly controlling the duty cycle in the clock distribution path, it can work at a frequency as high as 3.5?GHz. The DCC adopts the continuous-time integrator as the duty cycle detector. The output pulse is scaled down according to the input frequency, which reduces the control voltage ripple and expands the minimum operation frequency to 1?MHz. The test chip is fabricated using SMIC 0.18???m CMOS process. The experiment results show that the frequency range of the input signal was 1?MHz?C3.5?GHz, and the duty cycle range of the input signal is from 0.1?C99.9%. The peak-to-peak jitter and power dissipation are 33.3?ps and 0.6?mW, respectively, at an operating frequency of 2?GHz.     

LDMOS开关在不同频率下的热安全工作

研究了LDMOS器件内部的最高温度与开关频率之间的关系.结果表明:在较高频率工作时,器件内部的最高温度与器件的热容、功耗、占空比和连续工作时间有关,而与器件的热阻和信号周期无关,器件会一直处于升温状态;在较低频率工作时,器件内部的最高温度还与器件的热阻和周期有关.所得结果可作为功率器件在各种频率下工作时热安全工作的参考.     

Distributed-feedback quantum cascade lasers emitting in the 9-μmband with InP top cladding layers

Two different high performance quantum cascade distributed-feedback lasers with four quantum-well-based active regions and InP top cladding layers are presented. The first device, which emitted at 9.5 μm, was mounted junction down in order to get high average powers of up to 71 mW at -30°C and 30 mW at room temperature. The other device, which lased at 9.1 μm, was optimized for high pulsed operating temperatures and tested up to 150°C at 1.5% duty cycle. The emission of both lasers stayed single mode with more than 20-dB side-mode suppression ratio over the entire investigated power and temperature range