Physical origin of the excess thermal noise in short channel MOSFETs
TL;DR: In this paper, the physical origin of the excess thermal noise in short channel MOSFETs is explained based on numerical noise simulation and the impedance field representation and extraction method demonstrate that the drain current noise is dominated by source side contributions.
Abstract: The physical origin of the excess thermal noise in short channel MOSFETs is explained based on numerical noise simulation. The impedance field representation and extraction method demonstrate that the drain current noise is dominated by source side contributions. Analysis identifies local ac channel resistance variations as the primary controlling factor. The nonlocal nature of velocity results in a smaller derivative of the velocity with respect to the field which in turn causes a higher local ac resistance near the source junction.
Citations
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Book•
01 Jan 2006
TL;DR: In this article, the authors present a short history of the EKV most model and its application in IC design, and present an extended version of the model with an extended charge-based model.
Abstract: Foreword. Preface. List of Symbols. 1. Introduction. 1.1 The Importance of Device Modeling for IC Design. 1.2 A Short History of the EKV MOST Model. 1.3 The Book Structure. PART I: THE BASIC LONG-CHANNELINTRINSIC CHARGE-BASED MODEL. 2. Introduction. 2.1 The N-channel Transistor Structure. 2.2 Definition of charges, current, potential and electric fields. 2.3 Transistor symbol and P-channel transistor. 3. The Basic Charge Model. 3.1 Poisson's Equation and Gradual Channel Approximation. 3.2 Surface potential as a Function of Gate Voltage. 3.3 Gate Capacitance. 3.4 Charge Sheet Approximation. 3.5 Density of Mobile Inverted Charge. 3.6 Charge-Potential Linearization. 4. Static Drain Current. 4.1 Drain Current Expression. 4.2 Forward and Reverse Current Components. 4.3 Modes of Operation. 4.4 Model of Drain Current Based on Charge Linearization. 4.5 Fundamental Property: Validity and Application. 4.6 Channel Length Modulation. 5. The Small-Signal Model. 5.1 The Static Small-Signal Model. 5.2 A General Non-Quasi-Static Small-Signal Model. 5.3 The Quasi-Static Dynamic Small-Signal Model. 6. The Noise Model. 6.1 Noise Calculation Methods. 6.2 Low-Frequency Channel Thermal Noise. 6.3 Flicker Noise. 6.4 Appendices. Appendix : The Nyquist and Bode Theorems. Appendix : General Noise Expression. 7. Temperature Effects and Matching. 7.1 Introduction. 7.2 Temperature Effects. PART II: THE EXTENDED CHARGE-BASED MODEL. 8. Non-Ideal Effects Related to the Vertical Dimension. 8.1 Introduction. 8.2 Mobility Reduction Due to the Vertical Field. 8.3 Non-Uniform Vertical Doping. 8.4 Polysilicon Depletion. 8.4.1 Definition of the Effect. 8.5 Band Gap Widening. 8.6 Gate Leakage Current. 9. Short-Channel Effects. 9.1 Velocity Saturation. 9.2 Channel Length Modulation. 9.3 Drain Induced Barrier Lowering. 9.4 Short-Channel Thermal Noise Model. 10. The Extrinsic Model. 10.1 Extrinsic Part of the Device. 10.2 Access Resistances. 10.3 Overlap Regions. 10.4 Source and Drain Junctions. 10.5 Extrinsic Noise Sources. PART III: THE HIGH-FREQUENCY MODEL. 11. Equivalent Circuit at RF. 11.1 RF MOS Transistor Structure and Layout. 11.2 What Changes at RF?. 11.3 Transistor Figures of Merit. 11.4 Equivalent Circuit at RF. 12. The Small-Signal Model at RF. 12.1 The Equivalent Small-Signal Circuit at RF. 12.2 Y-Parameters Analysis. 12.3 The Large-Signal Model at RF. 13. The Noise Model at RF. 13.1 The HF Noise Parameters. 13.2 The High-Frequency Thermal Noise Model. 13.3 HF Noise Parameters of a Common-Source Amplifier. References. Index.
307 citations
TL;DR: In this paper, a charge-based model of the intrinsic part of the MOS transistor is presented, which is based on the forward and reverse charges q/sub f/ defined as the mobile charge densities, evaluated at the source and at the drain.
Abstract: This paper presents an overview of MOS transistor modeling for RF integrated circuit design. It starts with the description of a physical equivalent circuit that can easily be implemented as a SPICE subcircuit. The MOS transistor is divided into an intrinsic part, representing mainly the active part of the device, and an extrinsic part responsible for most of the parasitic elements. A complete charge-based model of the intrinsic part is presented. The main advantage of this new charge-based model is to provide a simple and coherent description of the DC, AC, nonquasi-static (NQS), and noise behavior of the intrinsic MOS that is valid in all regions of operation. It is based on the forward and reverse charges q/sub f/ and q/sub r/ defined as the mobile charge densities, evaluated at the source and at the drain. This intrinsic model also includes a new simplified NQS model that uses a bias and frequency normalization allowing one to describe the high-order frequency behavior with only two simple functions. The extrinsic model includes all the terminal access series resistances, and particularly the gate resistance, the overlap, and junction capacitances as well as a substrate network. The latter is required to account for the signal coupling occurring at RF from the drain to the source and the bulk, through the junction capacitances. The noise model is then presented, including the effect of the substrate resistances on the RF noise parameters. All the aspects of the model are validated for a 0.25-/spl mu/m CMOS process.
194 citations
Cites background from "Physical origin of the excess therm..."
...A recent work [ 51 ] claims that the traditional approach using a voltage noise source in the channel to model the contribution of an elementary noisy piece of channel is incorrect due to spatial correlation of the different voltage sources that have to be summed to get the total noise due to the channel....
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...Numerical noise simulations using local current noise sources [50] have shown that the physical origin of the excess noise is caused by a higher local ac resistance near the source junction [ 51 ]....
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...Noise simulations resulted in a noise excess factor increase for short-channel devices, reaching a typical value of two for devices having a 0.25- m channel length [50], [ 51 ]....
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TL;DR: A physical understanding of both intrinsic and extrinsic noise mechanisms in a MOSFET is developed in this article, where a survey of current public domain MOS models is presented, and a lack of comprehensive coverage of noise models is noted.
Abstract: 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 1/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
107 citations
Proceedings Article•
01 Jan 2004TL;DR: A new, completely analytical thermal noise model based on consistent physical assumptions for MOS transistors is presented.
Abstract: Note: (invited) Reference EPFL-CONF-149651 Record created on 2010-06-24, modified on 2017-05-12
80 citations
Cites background from "Physical origin of the excess therm..."
...Regarding the definition of diffusivity, we have noticed that a series of current literature about numerical noise simulation [20], [9], [21] as well as [8] used an incorrect definition, that is the use of cord mobility e instead of differential mobility....
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TL;DR: In this paper, the authors present a new, completely analytical thermal noise model based on consistent physical assumptions, including the absence of carrier heating, incorrect modeling of velocity saturation effect, wrong modeling of diffusivity, etc.
Abstract: Although some of the recently proposed compact models for thermal noise in MOS transistors exhibit a good match with experimental data, we believe most of the existing compact models suffer from incorrect physical assumptions or modeling (e.g., absence of carrier heating, incorrect modeling of velocity saturation effect, wrong modeling of diffusivity, etc.). This brief presents a new, completely analytical thermal noise model based on consistent physical assumptions.
79 citations
References
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Book•
01 Jan 1986
TL;DR: In this paper, the authors propose a method to generate 1/f noise noise in particular Amplifier Circuits Mixers by using thermal noise shot and flicker noise, respectively.
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.
1,134 citations
TL;DR: In this article, an analytical formulation of the thermal noise in short-channel MOSFETs, working in the saturation region, is presented, taking into account effects like the field dependent noise temperature and mobility, the device geometry and the channel length modulation, the back gate effect and the velocity saturation.
Abstract: An analytical formulation of the thermal noise in short-channel MOSFETs, working in the saturation region, is presented. For the noise calculation, we took into account effects like the field dependent noise temperature and mobility, the device geometry and the channel length modulation, the back gate effect and the velocity saturation. The derived data from the model are in good agreement with reported thermal noise measurements, regarding the noise bias dependence, for transistors with channel lengths shorter than 1 /spl mu/m. Since the present thermal noise models of MOS transistors are valid for channel lengths well above 1 /spl mu/m, the proposed model can be easily incorporated in circuit simulators like SPICE, providing an extension to the analytical thermal noise modeling suitable for submicron MOSFETs.
140 citations
TL;DR: A simple analytical model for the thermal channel noise of deep submicron MOS transistors including hot carrier effects is presented, verified by measurements and implemented in the standard BSIM3v3 SPICE model.
Abstract: In this paper, we present a simple analytical model for the thermal channel noise of deep-submicron MOS transistors including hot carrier effects. The model is verified by measurements and implemented in the standard BSIM3v3 SPICE model. We show that the consideration of this additional noise caused by hot carrier effects is essential for the correct simulation of the noise performance of a low noise amplifier in the gigahertz range.
122 citations
"Physical origin of the excess therm..." refers background in this paper
...This results in a dominant noise contribution near the drain junction, which is more significant when the hot carrier effects are included [5]–[7]....
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01 Jan 1966
106 citations
"Physical origin of the excess therm..." refers background in this paper
...[13]–[15], device noise at electrodes is determined by two independent factors: local fluctuations and their propagation to terminal electrodes....
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TL;DR: In this article, a model is proposed which can predict accurately both ac and noise performance (all four noise parameters: minimum noise figure NF min, equivalent noise resistance R n, optimized source resistance R opt and reactance X opt ) of MOSFETs based on s -parameter and noise measurements at microwave frequencies.
Abstract: In this paper, a model is proposed which can predict accurately both ac and noise performance (all four noise parameters: minimum noise figure NF min , equivalent noise resistance R n , optimized source resistance R opt and reactance X opt ) of MOSFETs based on s -parameter and noise measurements at microwave frequencies. This model includes the relevant high frequency noise sources (i.e. the channel thermal noise, the induced gate noise and its correlation with the channel thermal noise and the thermal noise from the gate and parasitic resistances). In order to confirm the accuracy of the model and obtain the intrinsic scattering and noise parameters of devices, two de-embedding techniques (probe pad equivalent circuit modeling and direct parasitic noise de-embedding) have been used to de-embed the probe pad parasitics from the measured noise and s -parameters of the device-under-test (DUT). In addition, because of the complexity of this noise model, a direct calculation technique for calculating the four noise parameters was developed based on the small-signal transistor's model. Finally, the impact of gate resistance, and the noise improvement using multi-finger gate design are investigated.
104 citations
"Physical origin of the excess therm..." refers background in this paper
...This results in a dominant noise contribution near the drain junction, which is more significant when the hot carrier effects are included [5]–[7]....
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