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On a Parasitic Bipolar Transistor Action in a Diode ESD Protection Device  [PDF]
Jin Young Choi
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.79199
Abstract: In this work, we show that an excessive lattice heating problem can occur in the diode electrostatic discharge (ESD) protection device connected to a VDDbus in the popular diode input protection scheme, which is favorably used in CMOS RF ICs. To figure out the reason for the excessive lattice heating, we construct an equivalent circuit for input human-body model (HBM) test environment of a CMOS chip equipped with the diode protection circuit, and execute mixed-mode transient simulations utilizing a 2-D device simulator. We analyze the simulation results in detail to show out that a parasitic pnp bipolar transistor action relating nearby p+-substrate contacts is responsible for the excessive lattice heating in the diode protection device, which has never been focused before anywhere.
Discharge Characteristics of a Triple-Well Diode-String ESD Clamp  [PDF]
Jin Young Choi
Circuits and Systems (CS) , 2018, DOI: 10.4236/cs.2018.95008
Abstract: In this work, DC and transient characteristics of a 4 diode string utilizing triple-well technologies as a VDD-VSS clamp device for ESD protection are analyzed in detail based on 2-dimensional device and mixed-mode simulations. It is shown that there exists parasitic pnp bipolar transistor action in this device leading to a sudden increase in DC substrate leakage if anode bias is getting high. Through transient simulations for a 2000 V PS-mode HBM ESD discharge event, it is shown that the dominant discharge path is the one formed by a parasitic pnpn thyristor and a parasitic npn bipolar transistor in series. Percentage ratios of the various current components regarding the anode current at its current peaking are provided. The mechanisms involved in ESD discharge inside the diode-string clamp utilizing triple-well technologies are explained in detail, which has never been done anywhere in the literature based on simulations or measurements.
行波管收集极的热分析  [PDF]
姚列明,杨中海,李斌,黄桃
强激光与粒子束 , 2006,
Abstract: ?随着行波管的大功率小型化,收集极的温度分布和采用的散热手段对行波管的正常工作有很大影响。利用ansys软件对行波管收集极的散热问题进行详细的模拟计算,分析比较了不同热流加载方式对收集极温度分布的影响。采用均匀热流加载定性地比较计算了自然冷却、风冷、单层水套和双层水套等不同散热条件下收集极的热耗散功率,计算结果与经验值一致,说明了所用模型和方法的正确性。模拟分析为行波管收集极的散热方案优化设计提供有效的参考依据和手段。
A Comparison Study of Input ESD Protection Schemes Utilizing NMOS, Thyristor, and Diode Devices  [PDF]
Jin Young Choi
Communications and Network (CN) , 2010, DOI: 10.4236/cn.2010.21002
Abstract: For three fundamental input-protection schemes suitable for high-frequency CMOS ICs, which utilize protection devices such as NMOS transistors, thyristors, and diodes, we attempt an in-depth comparison on HBM ESD robustness in terms of lattice heating inside protection devices and peak voltages developed across gate oxides in input buffers, based on DC, mixed-mode transient, and AC analyses utilizing a 2-dimensional device simulator. For this purpose, we construct an equivalent circuit model of input HBM test environments for CMOS chips equipped with input ESD protection circuits, which allows mixed-mode transient simulations for various HBM test modes. By executing mixed-mode simulations including up to six active protection devices in a circuit, we attempt a detailed analysis on the problems, which can occur in real tests. In the procedure, we suggest to a recipe to ease the bipolar trigger in the protection devices and figure out that oxide failure in internal circuits is determined by the peak voltage developed in the later stage of discharge, which corresponds to the junction breakdown voltage of the NMOS structure residing in the protection devices. We explain strength and weakness of each protection scheme as an input ESD protection circuit for high-frequency ICs, and suggest valuable guidelines relating design of the protection devices and circuits.
回旋行波管收集极的热分析  [PDF]
郑志清,罗勇,蒋伟,唐勇
强激光与粒子束 , 2013,
Abstract: ?为解决回旋管行波管收集极的散热问题,保障回旋行波管工作的可靠性和稳定性,利用cst电子仿真软件模拟出电子在回旋行波管中的运动轨迹,并因此确定了进入收集极的电子注的初始条件。利用ansys有限元软件对回旋行波管收集极的散热特性进行详细的模拟计算,分析比较了不同热流密度加载方式对收集极温度分布的影响。采用非均匀热流加载方式探究了水温和流速对收集极温度的影响,并对收集极的散热翼片的数目和尺寸进行了优化,最终得出了比较理想的结构。模拟结果优于经验值,说明了所用模型和方法的正确性。
空间行波管收集极的热特性分析  [PDF]
李延威,李建清
强激光与粒子束 , 2009,
Abstract: ?利用有限元方法对一ku波段空间行波管收集极的热特性进行了模拟计算,得到了收集极的温度分布图。分析比较了接触热阻和热辐射对热特性的影响,结果表明接触热阻明显地阻碍了热量的散失,使收集极整体温度有一定上升,而热辐射在使收集极各部分温度降低的同时,使温度分布更均匀。运用间接法进行了热-应力耦合分析,得到了收集极的位移场分布等值线图,进而确定该收集极采用的结构在热形变方面满足散热要求;并对在轴向加矩形翅片和在径向加圆形翅片两种散热方案进行了分析,得到了各自的优缺点,为散热方案的选择提供了依据,从而可以更好地提高散热效率。
模型参数对双极管差分对延时的影响
代铁军,杨肇敏
半导体学报 , 1998,
Abstract: 本文结合我们所开发的两种BiCMOS工艺,讨论了双极管模型参数对双极管差分对的影响.采用电荷控制法,推导得出了双极管差分对的延时公式.该公式物理意义明确直观,能清楚地解释双极管各模型参数、工作条件等因素对双极管差分对延时的影响,并能指导电路设计和工艺制造;最终公式中全部使用PSPICE参数,便于计算;该公式虽然只讨论了三个电容(发射结电容、集电结电容和衬底结电容)、三个电阻(发射极电阻、集电极电阻、基极电阻)、正向渡越时间和正向电流放大倍数八个参数,但其计算结果与PSPICE模拟结果呈现出良好的一致性.
多注毫米波行波管收集极的热设计  [PDF]
谢松廷,吕国强,杨军,潘明明
强激光与粒子束 , 2008,
Abstract: ?为解决多注毫米波行波管收集极的散热问题,保障行波管工作可靠性与稳定性,利用ansys有限元软件模拟分析了收集极的传热特性,针对性地调整和优化了收集极相关参数与结构。研究结果表明:接触热阻是造成收集极具有较高温升的一个重要因素,由接触热阻所造成的温升约占收集极内外温度差的1/3;并不是第二电极与磁环接触宽度越宽所对应的收集极散热能力就越强,而是在一定工作条件下其散热能力存在极限值;对于绝缘陶瓷材料,应根据绝缘陶瓷的温度特性以及行波管的功率大小来进行选择;翼片式散热器是一种符合设计要求的理想散热结构。
东极海区管角螺软体部的营养成分分析  [PDF]
朱爱意,赵向炯,杨运琪
南方水产科学 , 2008,
Abstract: 对东极海区野生管角螺(hemifusustuba)软体部营养成分进行了分析,结果显示,管角螺软体部干品(ds)的粗蛋白含量达80.777%,蛋白质中检出含有17种氨基酸,氨基酸含量达软体部干重的51.42%。蛋白质中必需氨基酸蛋氨酸+半胱氨酸的氨基酸分最高为85.94分,呈味氨基酸含量丰富,占氨基酸总量的48.62%;eaa/taa为40.57%、eaa/ntaa为68.72%,其必需氨基酸的构成比例基本符合fao/who模式;粗脂肪中脂肪酸含量齐全,多不饱和脂肪酸比例高。分析结论为管角螺是一种高蛋白低脂肪、具有优良保健和营养价值的食品。
超前管棚注浆支护技术在极复杂断层带中的应用  [PDF]
赵毅鑫,姜耀东,孟磊,王涛,刘华博
采矿与安全工程学报 , 2013,
Abstract: 基于煤矿巷道采用超前管棚注浆支护技术顺利通过复杂断层带的实际案例,研究了巷道通过极复杂断层带面临的破碎围岩变形控制问题。通过计算确定了超前管棚注浆支护的设计参数,采用数值计算手段分析了过断层区域不同支护条件下的围岩应力和巷道变形情况,并针对施工后的管棚支护巷道变形量进行了现场实测,总结了超前管棚注浆支护技术在巷道通过复杂断层带的成功经验。实践证明:超前管棚注浆支护技术提高了围岩的完整性及整体承载能力,能够形成较强的预支护体系,可应用于复杂断层带的破碎围岩变形控制,但需辅以物探手段提高注浆质量、加强监测才能保障巷道顺利通过复杂断层带,本文经验可对类似工程的设计和施工提供借鉴。
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