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Proceedings ArticleDOI

Hydrodynamic simulation of RF noise in deep-submicron MOSFETs

29 Sep 2003-pp 87-90

AbstractA noise model for MOSFETs based on analytical microscopic noise sources has been developed and noise simulations based on the hydrodynamic model have been performed. The drain and gate excess noise parameters and correlation coefficient are extracted and the reasons for noise parameter dependence on the channel length are explained.

Topics: Noise temperature (69%), Noise generator (69%), Flicker noise (68%), Noise (radio) (66%), Shot noise (65%)

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Citations
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Journal ArticleDOI
Abstract: For compact modeling of the noise in devices, one of the following three methods is usually applied: 1) An equivalent circuit based approach, 2) the classical Langevin or Klaassen-Prins approach, or 3) the impedance field method. It is well known that for long-channel MOST (where mobility degradation due to a lateral field is absent), all three methods obtain the same result. But it is still not recognized how these methodologies need to be changed when the mobility starts to depend on the electric field. In this work we demonstrate how these methodologies can be adapted to incorporate mobility degradation and show that for any arbitrary mobility model /spl mu/(E) all the methods yield the same expressions for induced gate and drain noise current, which demonstrates the equivalence of the methods. We also present, for the first time, a general expression of induced gate noise which is valid for any mobility model (an expression of the drain current noise was already presented in our previous work) and some very general expressions of noise parameters that can be used for noise modeling with any kind of mobility model.

38 citations


Journal ArticleDOI
Abstract: The open question whether excess noise is due to hot electrons or not is addressed for the first time by solving the full Langevin Boltzmann equation. Not only the bulk case is analyzed but also devices. In contrast to the well-known Monte Carlo method this new approach allows the investigation of the spatial origin of the terminal current noise. It is shown, that excess noise in devices is mainly due to cold or warm electrons. The contribution of hot electrons in a velocity saturation region is found to be negligible. This corroborates previous findings based on the less accurate impedance field method.

9 citations


Journal ArticleDOI
Abstract: For the first time, the effects of poly depletion on the RF noise performance of advanced CMOS transistors are reported and analyzed. Based on measurements and physical device simulations we quantify the increasing danger of poly gate depletion with downscaling on the RF noise parameters of CMOS devices. While poly depletion does not affect the minimum noise figure, it results in a degradation of the noise matching freedom for RFIC designers. This trend worsens with technology downscaling.

5 citations


Cites methods from "Hydrodynamic simulation of RF noise..."

  • ...We point out that the default parameters’ value of the physical models describing the carriers transport properties are used, although the value of the diffusivity coefficient used to determine the noise density fluctuations is corrected to account for deviation from the Einstein relation in short active region [16]....

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Proceedings ArticleDOI
12 Dec 2005
Abstract: The open question whether excess noise is due to hot electrons or not is addressed for the first time by solving the Langevin Boltzmann equation. Not only is the bulk case analyzed but also devices. In contrast to the well-known Monte Carlo method this new approach allows the investigation of the spatial origin of the terminal current noise. It is shown, that excess noise is mainly due to cold or warm electrons, whereas the contribution of hot electrons in a velocity-saturation region is negligible.

3 citations


Journal ArticleDOI
Abstract: A deterministic solver for the analysis of microscopic noise and small-signal fluctuations in junctionless nanowire field-effect transistors is presented, which is based on a self-consistent and simultaneous solution of the Poisson/Schrodinger/Boltzmann equations. It is verified that the numerical framework fulfills the vital properties of reciprocity and passivity in the small-signal sense, and yields Johnson–Nyquist noise under equilibrium conditions. Key figures such as the cutoff frequency, drain excess noise factor, the Fano factor, and gate/drain correlation coefficient are presented at various bias conditions. In this work we show that similar to the inversion-mode MOSFETs, the gate and drain current noises mainly stem from the warm electrons at the source side, whereas the hot electrons do not have a significant contribution. Also, our results show that the device behaves similar to long-channel FETs in terms of its excess noise even for a channel length of 10 nm, due to the strong control of its electrostatics by the all-around gate.

3 citations


References
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Book
01 Jan 1986
Abstract: Mathematical Methods Noise Characterization Noise Measurements Thermal Noise Shot Noise Generation - Recombination Noise Flicker Noise or 1/f Noise Noise in Particular Amplifier Circuits Mixers Miscellaneous Problems Appendixes Index.

1,125 citations


Journal ArticleDOI
Abstract: Classical semiconductor equations are based on the thermal equilibrium approximation. Limitations introduced by this approximation for the 2-D numerical modeling of n-channel silicon submicrometer MOS transistors are investigated. It is shown that the classical equations are accurate for predicting drain current for devices with effective channel lengths as small as 0.3 mu m. However, accurate substrate current modeling requires a more detailed level of simulation even for devices with longer channel lengths. The solution of the energy conservation equation is discussed. >

122 citations


Journal ArticleDOI
Abstract: An extraction method to obtain the induced gate noise (i~/sub g/~/sup 2/~) channel noise (i~/sub d/~/sup 2/~), and their cross correlation (i~/sub g/~i~/sub d/~*~) in submicron MOSFETs directly from scattering and RF noise measurements has been presented and verified by measurements. In addition, the extracted induced gate noise, channel noise, and their correlation in MOSFETs fabricated in 0.18-/spl mu/m CMOS process versus frequencies, bias conditions, and channel lengths are presented and discussed.

116 citations


Journal ArticleDOI
Abstract: For pt. I see ibid., vol. 49, pp. 1250-1257 (2002). Terminal current noise is investigated with Langevin-type drift-diffusion (DD) and hydrodynamic (HD) noise models for one-dimensional (1-D) N/sup +/ NN/sup +/ and P/sup +/ PP/sup +/ structures and a realistic two-dimensional (2-D) SiGe NPN HBT. The new noise models, which are suitable for technology computer aided design (TCAD), are validated by comparison with Monte Carlo (MC) device simulations for the 1-D structures including noise due to particle scattering and generation of secondary particles by impact ionization (II). It is shown that the accuracy of the usual approach based on the DD model in conjunction with the Einstein relation degrades under nonequilibrium conditions. 2-D MC noise simulations are found to be feasible only if the current correlation functions decay on a subpicosecond scale, what is not always the case.

61 citations


"Hydrodynamic simulation of RF noise..." refers background or methods in this paper

  • ...The coupling of energy and velocity fluctuations through the Joule term also creates a correction to the local noise source in case of the HD model [2]....

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  • ...The HD model is the one of [3] and in contrast to [2] this model is based on an analytical formulation of the microscopic noise sources, which is readily extended to the case of surface transport....

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  • ...(In the case of the HD model a more general definition of the transfer function must be used [2]....

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Proceedings ArticleDOI
08 Dec 2002
Abstract: A model for RF CMOS circuit design is presented that is capable of predicting drain and gate current noise without adjusting any parameters. Additionally, the presence of (i) noise associated with avalanche multiplication, and (ii) shot noise of the direct-tunneling gate current in leaky dielectrics is revealed.

33 citations