强反型区下纳米MOSFET的射频噪声机理分析

为了有效地表征纳米MOSFET强反型区下的射频噪声特性,研究了其噪声建模的方法。在分析45 nm MOSFET射频小信号等效电路参数提取结果的基础上,建立了该器件漏极电流噪声的简洁模型。该模型完整地表征了决定45 nm器件噪声机理的三个组成部分:本征漏极电流噪声、栅极管脚寄生电阻热噪声和栅漏衬底寄生电磁耦合噪声。噪声测量在验证所建模型准确性和精度的同时,还表明:45 nm MOSFET的本征漏极电流噪声为受抑制的散粒噪声,并且随着栅源偏压的降低受抑制性逐渐减弱直至消失。     

Light-wave guidance through stratified photonic crystal metamaterials synthesized by superinductive layers of metallic nanostrips

The electrodynamic properties of a novel class of photonic-crystal metamaterial platform entirely synthesized by ultralow-refractive-index suspended nanostrips embedded in a dielectric matrix are described and investigated. The optical properties of the homogeneous metamaterial platform can be understood on the basis of equivalent distributed circuit extraction from an electromagnetic model that has negatively distributed superinductive properties. Low propagation loss, temperature-insensitive characteristics, and ultracompact size are the main advantages of the proposed technology, making this new type of metamaterial an excellent candidate for use in compact multilayer nanophotonic integrated systems.     

Microwave-generated plasma in air under standard conditions

The possibility and feasibility of microwave-excited plasmas in air under standard conditions, as well as under moderate pressures of up to 5 bar, is demonstrated by using a quarter-wave coaxial resonator. The microwave energy is coupled into the resonator by an inductive loop attaining a match of better -15 dB. The equivalent circuit of the resonator allows to determine intrinsic resistance, inductance, and capacitance, additionally, the quality factor and, finally, the field strength inside the resonator can be deduced. By using this approximation a breakdown field of 300 kV/m is computed. The power levels used for exciting microwave plasmas are low enough to be manageable, e.g., 35 W     

Buck变换器内部本质安全性能评价判别式研究

为了建立起Buck变换器内部本质安全性能评价的相关判别式,首先以简单电感电路的电弧放电为研究对象,基于热引燃理论,采用持续发热点热源温度场模型,将初始燃烧容积的温度由最高值下降至气体混合物燃烧温度的时间是否大于化学反应的时间作为判断火花能否成功引燃气体混合物的临界条件,得到了相应的火花放电时间临界值的表达式。然后,基于爆炸性试验数据对采用等效电阻法和放电电流线性模型算得的Buck变换器电感开路电弧放电能量表达式进行了修正,进而建立了Buck变换器内部本质安全性能评价的能量判别式和放电时间判别式。验证结果表明了所求放电时间临界值的合理性和所建立判别式的正确性。     

关于半导体漂移三极管在饱和区工作时的储存时间问题

半导体三极管在饱和区工作时,其等效电路可以用一个三极管及一个由集电极及基极构成的二极管联成的电路表示出来,其中三极管在有源区工作,而二极管在正向偏压下工作。这样的等效电路具有比较明显的物理意义。利用这个电路来求漂移管在一个共基极电路中脉冲工作下的储存时间。解出非平衡少数载流子的连续性方程,求出二极管p-n结附近非平衡少数载流子密度的稳定态分量及暂态分量,从而得到决定储存时间的方程。计算结果表明,储存时间与基极区域及集电极区域中非平衡载流子的寿命及表面复合速度有关。减少寿命及增加表面复合速度就可以减少储存时间。     

一种InP双异质结双极晶体管小信号物理模型及其提取方法

研究了InP双异质结双极晶体管（DHBT）的能带结构对集电极电容的影响,解决了传统方法不能准确提取InP DHBT集电极电容的问题.考虑了基极-发射极和集电极-发射极引线间的交叠电容,并从物理上区分了InP DHBT的本征电阻、外部电阻与寄生电阻,建立了一个基于物理的InP基DHBT小信号模型.同时提出了一套直接提取模型参数的方法,该方法无需引入数学优化,具有清晰的物理意义.提取的结果在很宽的偏置范围内准确地拟合了器件特性,验证了模型的准确性与提取方法的有效性. 关键词： InP双异质结双极晶体管 集电极电容 小信号模型 参数提取     

GaInP/GaAs异质结双极晶体管小信号模型参数提取的新方法

提出了一种直接提取GaInP/GaAs异质结双极晶体管(HBT)小信号模型参数的新方法.该方法基 于HBT器件S参数的测试数据，对HBT的小信号模型进行电路网络分析，利用S，Z，Y参数关系 以及电路“抽出”的技巧，分别对HBT小信号模型的寄生参数和本征元件参数进行提取，建 立了一套完整的直接提取HBT小信号模型参数的新方法.与文献报道HBT小信号模型参数提取 的方法相比，该方法的优点是，提取过程具有简明清晰的物理意义，无需建立特殊的测试结 构，无需引入繁琐的数学优化过程，提取速度快，并且具有比较好的精度和较宽频带范围的 适用性等. 关键词： GaInP/GaAs HBT 参数提取 小信号模型     

Extrinsic equivalent circuit modeling of InP HEMTs based on full-wave electromagnetic simulation

With the widespread utilization of indium-phosphide-based high-electron-mobility transistors (InP HEMTs) in the millimeter-wave (mmW) band, the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent. We present an InP HEMT extrinsic parasitic equivalent circuit, in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_mgd are taken into account for the high-frequency magnetic field coupling between device electrodes. Based on the suggested parasitic equivalent circuit, through HFSS and advanced design system (ADS) co-simulation, the equivalent circuit parameters are directly extracted in the multi-step system. The HFSS simulation prediction, measurement data, and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit. The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.     

SiGe HBT大信号等效电路模型

基于SiGe HBT(异质结双极晶体管)的物理模型，建立了描述SiGe HBT的大信号等效电路模型.该等效电路模型考虑了准饱和效应和自热效应等，模型分为本征和非本征两部分，物理意义清晰，拓扑结构相对简单.该模型嵌入了PSPICE软件的DEVEO(器件方程开发包)中.在PSPICE软件资源的支持下，利用该模型对SiGe HBT器件进行了交直流特性模拟分析，模拟结果与理论分析结果相一致，并且与文献报道的结果符合较好. 关键词： SiGe HBT 等效电路模型 PSPICE     

Small-signal modeling of graphene barristors

This paper presents a small-signal model for graphene barristor, a promising device for the future nanoelectronics industry. Because of the functional similarities to the conventional FET transistors, the same configuration and parameters, as those of FETs, are assumed for the model. Transconductance, output resistance, and parasitic capacitances are the main parameters of the small signal equivalent circuit modeled in this work. Recognizing the importance of physical modeling of novel semiconductor devices, we develop physical compact expressions for the device radio-frequency characteristics. Furthermore, we clarify the physics behind the variation of the characteristics as the device parameters change. We also validate our model results with available simulation results. Impact of equilibrium Schottky barrier height of the graphene–silicon junction on the radio frequency performance of barristor is investigated, too.     

基于新型自耦合非对称阶梯阻抗谐振器的小型化三通带平衡滤波器

针对平衡滤波器的高集成度和高选择性的应用需求,基于一种新型自耦合非对称阶梯阻抗谐振器提出了一种具有高选择性的小型化三通带平衡滤波器。首先通过该平衡滤波器的差模和共模等效电路详细分析了其谐振器结构的谐振特性,并利用差模等效电路下的前三个谐振模式来分别实现三个通带。另外通过在电路对称面上加载电容和电阻元件来提高对共模噪声的抑制,且不影响差模频率响应特性。基于提出的多模平衡滤波器结构和设计方法,设计了一个通带频率为2.75/4.46/6.21 GHz的三通带平衡滤波器,并对其进行了加工和测试,结果表明,该结构可以实现紧凑的体积和高选择特性,并且具有很好的共模抑制特性。     

一类任意m×n阶矩形网络的电特性

任意矩形电路网络中的电位分布问题一直是科学研究的难题.本研究发展了研究电阻网络的递推-变换(RT)理论使之能够用于计算任意m×n阶电路网络模型.研究了一类含有任意边界的m×n阶矩形网络的电位分布及等效电阻,这是一个之前一直没有解决的深刻问题,因为之前的研究依赖于规则的边界条件或一个含有零电阻的边界条件.其他方法如格林函数技术和拉普拉斯矩阵方法计算电位函数比较困难,研究含有任意边界的电阻网络也是不可能的.电位函数问题是自然科学和工程技术领域研究的一个重要内容,如拉普拉斯方程的求解问题就是其中之一.本文给出了含有一条任意边界的m×n矩形电阻网络的节点电位函数解析式,并且得到了任意两节点间的等效电阻公式,同时导出了一些特殊情形下的结果.在对不同结果的比较研究时,得到了一个新的数学分式恒等式.     

包含外壳磁阻的微型平衡电枢换能器仿真模型的阻抗和振动分析

现有的“E”型平衡电枢等效磁路模型仿真研究通常不考虑金属外壳磁阻带来的影响。为了解决平衡电枢换能器中因金属外壳和平衡电枢紧密接触带来的非线性磁阻问题，在现有的平衡电枢换能器等效磁路模型上加入了外壳磁阻影响。分析等效磁路模型磁通部分和力学部分的状态空间方程在不同参数条件下的仿真结果，总结不同参数对该模型阻抗和振膜位移的影响情况。通过仿真对比，外壳磁阻对平衡电枢换能器位移频率响应曲线的影响为1～3 dB。对于组装后包含金属外壳的平衡电枢耳机、助听器产品降低频率响应曲线偏差具有一定的指导意义。     

Debye's relaxation frequency: A poor man's approach

We present a simple approach to introduce Debye's relaxation frequency. Our model is based on a kinetic equation at the electrodes, describing the time variation of the ionic charge pushed at the limiting surfaces by the effective electric field. In a first approximation the surface region where the ions are confined is assumed of negligible thickness. We show that this approximation allows to define a frequency at which the effective resistance of the sample begins to decrease. This frequency coincides with Debye's relaxation frequency. An equivalent electric circuit describing the frequency dependence of the effective impedance of the cell, valid in this approximation, is presented. In a second approximation we discuss the influence of a perfectly dielectric surface layer on the relaxation frequency, where the electrolytic cell is described by means of a Maxwell-Wagner system. The equivalent electrical circuit is discussed.     

Theoretical Study of Millimeter Wave Harmonic Oscillator Stabilized with a Transmission Cavity

An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity.     

PIN限幅器的高功率微波单脉冲效应研究

基于PIN限幅器的等效电路模型,构建了PIN限幅器HPM效应ADS等效电路仿真模型,利用HPM注入实验和等效电路仿真相结合的方法,研究了单个微波脉冲作用下PIN限幅器的响应规律,获取了HPM作用结束后限幅器限幅持续时间与注入脉冲功率、脉宽的对应关系,并对限幅器的限幅持续过程进行了分析。仿真与实验结果表明:PIN限幅器限幅持续时间随着微波脉冲功率和脉宽的增大而变大,实验和仿真结果趋势一致,该研究使用的ADS等效电路模型可以应用于PIN限幅器的高功率微波瞬态响应特性分析研究。     

Observation of nonconservation characteristics of radio frequency noise mechanism of 40-nm n-MOSFET

Bias non-conservation characteristics of radio-frequency noise mechanism of 40-nm n-MOSFET are observed by modeling and measuring its drain current noise. A compact model for the drain current noise of 40-nm MOSFET is proposed through the noise analysis. This model fully describes three kinds of main physical sources that determine the noise mechanism of 40-nm MOSFET, i.e., intrinsic drain current noise, thermal noise induced by the gate parasitic resistance, and coupling thermal noise induced by substrate parasitic effect. The accuracy of the proposed model is verified by noise measurements, and the intrinsic drain current noise is proved to be the suppressed shot noise, and with the decrease of the gate voltage, the suppressed degree gradually decreases until it vanishes. The most important findings of the bias non-conservative nature of noise mechanism of 40-nm n-MOSFET are as follows.(i) In the strong inversion region, the suppressed shot noise is weakly affected by the thermal noise of gate parasitic resistance. Therefore, one can empirically model the channel excess noise as being like the suppressed shot noise.(ii) In the middle inversion region, it is almost full of shot noise.(iii) In the weak inversion region, the thermal noise is strongly frequency-dependent, which is almost controlled by the capacitive coupling of substrate parasitic resistance. Measurement results over a wide temperature range demonstrate that the thermal noise of 40-nm n-MOSFET exists in a region from the weak to strong inversion, contrary to the predictions of suppressed shot noise model only suitable for the strong inversion and middle inversion region. These new findings of the noise mechanism of 40-nm n-MOSFET are very beneficial for its applications in ultra low-voltage and low-power RF, such as novel device electronic structure optimization, integrated circuit design and process technology evaluation.     

Microwave impedance measurements on resonant tunnelin diodes with asymmetric spacer layers

Scattering parameters (S parameters) have been measured up to 40GHz on GaAs/AlAs resonant tunneling diodes containing asymmetric spacer layers. On-wafer microwave probing techniques were used. A hysteresis was observed in the vicinity of the negative differential resistance (NDR) region. Unlike the one observed in dc current-voltage measurements, this hysteresis was not affected by oscillations and believed to be intrinsic. The impedance data has been fitted to a lumped equivalent circuit model and capacitance-voltage (C-V) characteristic extracted. In addition to the already reported capacitance peak in the NDR region, a smaller peak at a lower voltage was found. In comparison to the self-consistent calculation, the smaller peak is due to the electrons discharging from accumulation region between the emitter barrier and the cathode spacer layer. The C-V result agrees qualitatively with the theoretical calculation. It supports the theoretical argument that the negative conductance can be increased by increasing the cathode spacer layer, however, there is also an increase in capacitance and the cutoff frequency may be reduced.     

Expressions for Entropy Production Rate of Fuel Cells

基于燃料电池的一般模型,应用电化学和热力学理论导出燃料电池系统在不同条件下熵产生率的表示式．为了分析存在实际燃料电池中不可逆损失的影响,引进燃料电池的等效电路,直接将燃料电池的不可逆因子表示为内电阻、漏电阻和负载电阻的函数．进而计算燃料电池的最大输出功率和效率,讨论燃料电池的优化运行,确定负载电阻的匹配条件,从而得到一些有意义的结果．     

Conditions for the production of a single conducting nanostructure by electroforming

The process of electroforming (the production of a carboniferous conducting medium when the current flows through an organic material under a high electric field) in open sandwichlike structures with an insulating gap several tens of nanometers in width is considered. It is shown experimentally that there are factors that both favor (external ballast resistor) and prevent (local spreading resistance and the presence of the initial conductivity in the insulating gap) the production of a single conducting element between the electrodes. A simple model of the process in terms of the equivalent electric circuit is proposed. The model helps to find the trade-off between these factors and to construct an I-V diagram, which exhibits a region within which a single conducting nanostructure can be electroformed. An expression that relates the minimum permissible resistance of the nanostructure to its geometric parameters is derived.