Compact Noise Models for MOSFETs

A physical understanding of both intrinsic and extrinsic noise mechanisms in a MOSFET is developed. Intrinsic noise mechanisms fundamental to device operation include channel thermal noise, induced gate noise, and induced substrate noise. While the effect of channel thermal noise is observable at zero drain-to-source voltage, the induced gate and substrate noise do not manifest themselves under these conditions. However, the attendant fluctuations in the channel charge are observable by the passage of electric current through the device. Extrinsic noise mechanisms manifested due to structural evolution of the MOSFET include the distributed gate resistance noise, distributed substrate resistance noise, bulk charge effects, substrate current supershot noise, gate current noise, excess channel noise, and$hbox1/f$noise. Where available, compact noise models covering these noise mechanisms are explained. Also, where possible, methods of suppression of these mechanisms are highlighted. A survey of current public domain MOS models is presented, and a lack of comprehensive coverage of noise models is noted. Open areas of MOSFET noise research in the sub-hundred-nanometer regime are also highlighted. With suitable adaptation, noise concepts elucidated in the context of MOS transistors have a much wider applicability to the operation of HEMTs, JFETs, MESFETs, and other field-effect devices.     

短沟道三材料柱状围栅MOSFET的解析模型

在柱坐标系下利用电势的抛物线近似,求解二维泊松方程得到了短沟道三材料柱状围栅金属氧化物半导体场效应管的中心及表面电势。推导了器件阈值电压、亚阈值区电流和亚阈值摆幅的解析模型,分析了沟道直径、栅氧化层厚度和三栅长度比对阈值电压、亚阈值区电流和亚阈值摆幅的影响。利用Atlas对具有不同结构参数的器件进行了模拟研究和比较分析。结果表明,基于解析模型得到的计算值与模拟值一致,验证了所建模型的准确性,为设计和应用此类新型器件提供了理论基础。     

A Review of Core Compact Models for Undoped Double-Gate SOI MOSFETs

In this paper, we review the compact-modeling framework for undoped double-gate (DG) silicon-on-insulator (SOI) MOSFETs. The use of multiple gates has emerged as a new technology to possibly replace the conventional planar MOSFET when its feature size is scaled to the sub-50-nm regime. MOSFET technology has been the choice for mainstream digital circuits for very large scale integration as well as for other high-frequency applications in the low-gigahertz range. But the continuing scaling of MOSFET presents many challenges, and multiple-gate, particularly DG, SOI devices seem to be attractive alternatives as they can effectively reduce the short-channel effects and yield higher current drive. Core compact models, including the analysis for surface potential and drain-current, for both the symmetric and asymmetric DG SOI MOSFETs, are discussed and compared. Numerical simulations are also included in order to assess the validity of the models reviewed     

短沟道MOSFET本征电容模型的研究

<正> 一、引言 随着MOS集成电路向短沟道、高速化发展,MOS晶体管电容对电路性能的影响更为突出。对电路性能影响较大的栅—漏,栅—源本征电容C_(GD),C_(GS)与长沟器件的主要不同是:(1)饱和区C_(GD)≠0,随着沟道缩短,C_(GD)占总本征栅电容的比例增大。(2)C_(GD)由饱和区到线性区呈平缓过渡状。(3)饱和区C_(GS)减小,并由次开启到饱和区的上升趋势变缓。分析表明,栅电容的短沟效应与沟长调制和速度饱和迁移率有关。     

High-Frequency Noise of Modern MOSFETs: Compact Modeling and Measurement Issues

Compact modeling of the most important high-frequency (HF) noise sources of the MOSFET is presented in this paper, along with challenges in noise measurement and deembedding of future CMOS technologies. Several channel thermal noise models are reviewed and their ability to predict the channel noise of extremely small devices is discussed. The impact of technology scaling on noise performance of MOSFETs is also investigated by means of analytical expressions. It is shown that the gate tunneling current has a significant impact on MOSFETs noise parameters, especially at lower frequencies. Limitations of some commonly used noise models in predicting the HF noise parameters of modern MOSFETs are addressed and methods to alleviate some of the limitations are discussed.     

射频MOSFET噪声模型研究

对0.13μm MOSFET噪声建模和参数提取技术进行了研究,在精确地提取了小信号模型参数之后,利用噪声相关矩阵技术从测量的散射参数和射频噪声参数直接提取了栅极感应噪声电流■、沟道噪声电流■和它们的相关系数,并用PRC模型中的参数来表示。将参数提取结果带入ADS中进行仿真,在2～8GHz频段上仿真结果与测量数据吻合良好。     

城市移动数字电视地面广播的信道噪声模型

21世纪以来,中国的一些大城市先后开展了数字电视地面广播试验,并实现了车载移动接收数字电视.试验中发现:车载天线因时空限制难以避开干扰源,白噪声与脉冲相混合的噪波不断地影响着车载数字电视系统的接收效果.为了进行高效的传播信号覆盖规划,需掌握实际运行环境中数字电视地面广播信道的噪声情况.本文介绍了上海市内公共交通线上UHF频段内某个频道的平均噪声功率测量结果;通过对噪声功率概率累积分布曲线的回归分析,不仅获得城市中三个典型交通环境下该UHF频道的噪声系数模型,而且给出了频道噪声系数统计分布的上侧十分位数K倍方差值.     

Synthesized Compact Models and Experimental Verifications for Substrate Noise Coupling in Mixed-Signal ICs

A synthesized compact modeling (SCM) approach for substrate coupling analysis is presented. The SCM is formulated using a scalable$Z$matrix approach for heavily doped substrates with a lightly doped epitaxial layer and using a nodal lumped resistance approach for lightly doped substrates. The SCM models require a set of process-dependent fitting coefficients and incorporate geometrical parameters of the substrate ports in a compact form that includes size, perimeter, and separation defined using the geometric mean distance to accommodate both far-field and near-field effects. The SCM approach is verified based on measurement data from two test chips, one in a custom lightly doped process and the other one using a 0.18-$muhbox m$BiCMOS lightly doped foundry process. The model accuracy is shown to be within 15% compared to measured data extracted from the test patterns. The SCM is exploited with application examples to show substrate model generation efficiency and accuracy at different levels of complexity, including a full chip substrate noise distribution analysis for a 2 mm by 2 mm chip with 319 substrate contacts.     

一种改进的深亚微米MOSFET噪声模型

提出一种基于小信号的噪声模型,在精确提取0.13 μm MOSFET的小信号参数后,结合Pospieszalsik和pucel模型,运用噪声相关矩阵转换技术提取出所有噪声参数。利用ADS建立噪声模型,在2～20 GHz频率范围内,仿真结果与测量结果吻合良好,验证了模型的准确性。     

Compact Modeling of Ballistic Nanowire MOSFETs

Nanowire MOSFETs attract attention due to the probable high performance and the excellent controllability of device current. We present a compact model of ballistic nanowire MOSFET that aids our understanding of physics and the overall properties of the device. The relationship between the gate overdrive and the carrier density is derived and combined with the current expression to yield the current–voltage ($I$ –$V$) characteristics. The subthreshold characteristics and the short channel effect are also discussed. The effects of the quantum capacitance on device characteristics are analyzed. The low-temperature expression is also derived, and the relation to quantum conductance is discussed. The $I$– $V$ characteristics are numerically evaluated and examined, employing a reported subband model. The drain- and gate-bias dependences of device current are shown, and the effects of the quantum capacitance and conductance on these characteristics are indicated.      

Finite Mixture Noise Models for Mobile Digital Television Channel on Urban Terrestrial Broadcasting

Since 21st century, the test service for digital TV terrestrial broadcasting has been successively carried out in some Chinese big cities, and bus commuters can watch TV programs while traveling in the signal-covered regions. When the digital mobile TV coverage is planned, the level of radio noise in environments is of considerable concern to designers. In this paper the results of average noise power of a digital TV channel in a UHF band on public transportation courses are introduced. Not only the noise factors but also the K times variance deviation of the upper decile of noise factors under three typical communication environments has been obtained through the analysis of nonlinear regression of cumulative distribution functions on the test results. Through the trials of mobile reception of digital television, two coverage plans have been compared; The results show that the coverage effect for the model based on interference statistical distributions is higher than the one based on AWGN noise.     

BJT等效电路模型的发展

随着BJT尺寸的缩小以及BJT广泛应用于高速和RF电路,有效及准确的BJT电路设计要求更加精确的等效电路模型.通过介绍模型的基本原理及其对BJT器件关键物理效应的模拟,描述不同模型开发者采用的方式,结合仿真结果分析不同模型的特点.主要从以下几个方面展开:模型的大信号等效电路图;归一化电荷的计算,转移电流表达式;晶体管二阶效应模型,包括基区宽度调制效应(即Early效应)、大注入效应等;大电流条件下的Kirk效应,准饱和效应等.     

亚100nm体硅MOSFET集约I-V模型

利用“局域化”的概念和二维泊松方程的解析解，建立了沟道方向上二维量子效应对阈电压的修正模型．基于密度梯度理论，建立了多晶硅栅内量子效应对阈电压的修正模型．在此基础上，结合弹道理论，开发了一个适用于亚100nm MOSFET的集约I-V模型．通过与TSMC提供的沟长为45nm实际器件测试结果，以及与三组亚100nm MOSFET的数值模拟结果的比较，证明了该模型具有良好的精度（平均误差小于8%）和可延伸性．     

亚100nm体硅MOSFET集约I-V模型

利用"局域化"的概念和二维泊松方程的解析解,建立了沟道方向上二维量子效应对阈电压的修正模型.基于密度梯度理论,建立了多晶硅栅内量子效应对阈电压的修正模型.在此基础上,结合弹道理论,开发了一个适用于亚100nm MOSFET的集约I-V模型.通过与TSMC提供的沟长为45nm实际器件测试结果[1],以及与三组亚100nm MOSFET的数值模拟结果的比较,证明了该模型具有良好的精度(平均误差小于8%)和可延伸性.     

Low-Frequency Noise Phenomena in Switched MOSFETs

In small-area MOSFETs widely used in analog and RF circuit design, low-frequency (LF) noise behavior is increasingly dominated by single-electron effects. In this paper, the authors review the limitations of current compact noise models which do not model such single-electron effects. The authors present measurement results that illustrate typical LF noise behavior in small-area MOSFETs, and a model based on Shockley-Read-Hall statistics to explain the behavior. Finally, the authors treat practical examples that illustrate the relevance of these effects to analog circuit design. To the analog circuit designer, awareness of these single-electron noise phenomena is crucial if optimal circuits are to be designed, especially since the effects can aid in low-noise circuit design if used properly, while they may be detrimental to performance if inadvertently applied     

Explicit Continuous Models for Double-Gate and Surrounding-Gate MOSFETs

Explicit continuous models for both double-gate (DG) and surrounding-gate (SG) MOSFETs are presented. These models evolve from previous DG and SG MOSFETs models, which need to solve implicit equations for intermediate parameters by numerical iteration or the table lookup method. By developing approximate explicit solutions for the intermediate parameters, we can express the drain current, terminal charge, transconductance, and transcapacitance as explicit functions of applied voltages as well as the structural parameters. High accuracy and efficiency, combined with inherited favorable features from the previous models, make these new models suitable for circuit simulation programs.     

Channel noise modeling of deep submicron MOSFETs

This brief presents a new channel noise model using the channel length modulation (CLM) effect to calculate the channel noise of deep submicron MOSFETs. Based on the new channel noise model, the simulated noise spectral densities of the devices fabricated in a 0.18 /spl mu/m CMOS process as a function of channel length and bias condition are compared to the channel noise directly extracted from RF noise measurements. In addition, the hot electron effect and the noise contributed from the velocity saturation region are discussed.     

Temperature Dependence of High Frequency Noise Behaviors for RF MOSFETs

For the first time, the temperature dependences of radio frequency (RF) metal oxide semiconductor field effect transistors' intrinsic noise currents, including the induced gate noise current $(i_{g})$, channel noise current $(i_{d})$ and their correlation noise current, are experimentally investigated. The power spectral densities for the induced gate noise current and correlation noise current are found to rise as temperature increases, and decline for the channel noise current. Moreover, by using van der Ziel's noise model, our experimental results show that, besides ambient temperature, the channel conductance is the main factor dominating the RF noise behaviors. Finally, bias dependence results are also presented.      

短沟道MOST阈值电压温度系数的分析

本文分析了短沟道ＭＯＳＴ阈值电压在室温以上的温度特性，并给出了它的温度系数计算公式。根据计算结果，可以得到如下结论：短沟道ＭＯＳＴ的阈值电压温度系数随着沟道长度缩短而减小．与长沟道ＭＯＳＴ相似，在一定的温区范围内，可以把短沟道ＭＯＳＴ的阈值电压温度系数作为常数，用线性展开式来表达阈值电压的温度特性。     

Channel length independent subthreshold characteristics insubmicron MOSFETs

This work reports an anomalous subthreshold characteristic of the MOSFET for the first time. It is observed that the subthreshold characteristic does not change as the channel length decreases. The cause of channel length independent subthreshold characteristics is identified as the localized pileup of channel dopants near the source and drain ends of the channel. The low surface potential of this pileup region limits the subthreshold current of MOSFET. As a result, the ratio of on-current to off-current for this MOSFET increases as the channel length is reduced, which is an important parameter for low-voltage operation. It is found that a MOSFET with channel length independent subthreshold characteristic is more suitable for low-voltage operation