Showing papers on "Noise (electronics) published in 2006"

H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations

Abstract: SUMMARY Ambient vibration techniques such as the H/V method may have the potential to significantly contribute to site effect evaluation, particularly in urban areas. Previous studies interpret the so-called Nakamura’s technique in relation to the ellipticity ratio of Rayleigh waves, which, for a high enough impedance contrast, exhibits a pronounced peak close to the fundamental S-wave resonance frequency. Within the European SESAME project (Site EffectS assessment using AMbient Excitations) this interpretation has been tested through noise numerical simulation under well-controlled conditions in terms of source type and distribution and propagation structure. We will present simulations for a simple realistic site (one sedimentary layer over bedrock) characterized by a rather high impedance contrast and low quality factor. Careful H/V and array analysis on these noise synthetics allow an in-depth investigation of the link between H/V ratio peaks and the noise wavefield composition for the soil model considered here: (1) when sources are near (4 to 50 times the layer thickness) and surficial, H/V curves exhibit one single peak, while the array analysis shows that the wavefield is dominated by Rayleigh waves; (2) when sources are distant (more than 50 times the layer thickness) and located inside the sedimentary layer, two peaks show up on the H/V curve, while the array analysis indicates both Rayleigh waves and strong S head waves; the first peak is due to both fundamental Rayleigh waves and resonance of head S waves, the second is only due to the resonance of head S waves; (3) when sources are deep (located inside the bedrock), whatever their distance, H/V ratio exhibit peaks at the fundamental and harmonic resonance frequencies, while array analyses indicate only non-dispersive body waves; the H/V is thus simply due to multiple reflections of S waves within the layer. Therefore, considering that experimental H/V ratio (i.e. derived from actual noise measured in the field) exhibit in most cases only one peak, we conclude that H/V ratio is (1) mainly controlled by local surface sources, (2) mainly due to the ellipticity of the fundamental Rayleigh waves. Then the amplitude of H/V peak is not able to give a good estimate of site amplification factor.

Counting statistics of single electron transport in a quantum dot.

Abstract: We have measured the full counting statistics of current fluctuations in a semiconductor quantum dot (QD) by real-time detection of single electron tunneling with a quantum point contact. This method gives direct access to the distribution function of current fluctuations. Suppression of the second moment (related to the shot noise) and the third moment (related to the asymmetry of the distribution) in a tunable semiconductor QD is demonstrated experimentally. With this method we demonstrate the ability to measure very low current and noise levels.

Decoherence of Flux Qubits due to 1 / f Flux Noise

Abstract: We have investigated decoherence in Josephson-junction flux qubits. Based on the measurements of decoherence at various bias conditions, we discriminate contributions of different noise sources. We present a Gaussian decay function extracted from the echo signal as evidence of dephasing due to 1/f flux noise whose spectral density is evaluated to be about (10(-6)Phi0)2/Hz at 1 Hz. We also demonstrate that, at an optimal bias condition where the noise sources are well decoupled, the coherence observed in the echo measurement is limited mainly by energy relaxation of the qubit.

Bidirectional Counting of Single Electrons

Abstract: A bidirectional single-electron counting device is demonstrated. Individual electrons flowing in forward and reverse directions through a double quantum dot are detected with a quantum point contact acting as a charge sensor. A comprehensive statistical analysis in the frequency and time domains and of higher order moments of noise reveals antibunching correlation in single-electron transport through the device itself. The device can also be used to investigate current flow in the attoampere range, which cannot be measured by existing current meters.

Charge-Based MOS Transistor Modeling - The EKV Model for Low-Power and RF IC Design

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.

A mathematical model of noise in narrowband power line communication systems

Abstract: This manuscript introduces a mathematically tractable and accurate model of narrowband power line noise based on experimental measurements. In this paper, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power line noise can be described in close form. The periodic function that represents the variance is then approximated with a small number of parameters. The noise waveform generated with this model shows good agreement with that of actually measured noise. Noise waveforms generated by different models are also compared with that of the proposed model.

Decoherence from ensembles of two-level fluctuators

Abstract: 1/f noise, the major source of dephasing in Josephson qubits, may be produced by an ensemble of two-level systems. Depending on the statistical properties of their distribution, the noise distribution can be Gaussian or non-Gaussian. The latter situation is realized, for instance, when the distribution of coupling strengths has a slowly decaying power-law tail. In this regime, questions of self-averaging and sample-to-sample fluctuations become crucial. We study the dephasing process for a class of distribution functions and analyse the self-averaging properties of the results.

Noise analysis and characterization of a sigma-delta capacitive microaccelerometer

Abstract: This paper reports a high-sensitivity low-noise capacitive accelerometer system with one micro-g//spl radic/Hz resolution. The accelerometer and interface electronics together operate as a second-order electromechanical sigma-delta modulator. A detailed noise analysis of electromechanical sigma-delta capacitive accelerometers with a final goal of achieving sub-/spl mu/g resolution is also presented. The analysis and test results have shown that amplifier thermal and sensor charging reference voltage noises are dominant in open-loop mode of operation. For closed-loop mode of operation, mass-residual motion is the dominant noise source at low sampling frequencies. By increasing the sampling frequency, both open-loop and closed-loop overall noise can be reduced significantly. The interface circuit has more than 120 dB dynamic range and can resolve better than 10 aF. The complete module operates from a single 5-V supply and has a measured sensitivity of 960 mV/g with a noise floor of 1.08 /spl mu/g//spl radic/Hz in open-loop. This system can resolve better than 10 /spl mu/g//spl radic/Hz in closed-loop.

Computing Timing Jitter From Phase Noise Spectra for Oscillators and Phase-Locked Loops With White and $1/f$ Noise

Abstract: Phase noise and timing jitter in oscillators and phase-locked loops (PLLs) are of major concern in wireless and optical communications. In this paper, a unified analysis of the relationships between time-domain jitter and various spectral characterizations of phase noise is first presented. Several notions of phase noise spectra are considered, in particular, the power-spectral density (PSD) of the excess phase noise, the PSD of the signal generated by a noisy oscillator/PLL, and the so-called single-sideband (SSB) phase noise spectrum. We investigate the origins of these phase noise spectra and discuss their mathematical soundness. A simple equation relating the variance of timing jitter to the phase noise spectrum is derived and its mathematical validity is analyzed. Then, practical results on computing jitter from spectral phase noise characteristics for oscillators and PLLs with both white (thermal, shot) and 1/f noise are presented. We are able to obtain analytical timing jitter results for free-running oscillators and first-order PLLs. A numerical procedure is used for higher order PLLs. The phase noise spectrum needed for computing jitter may be obtained from analytical phase noise models, oscillator or PLL noise analysis in a circuit simulator, or from actual measurements

High resolution frequency standard dissemination via optical fiber metropolitan network

Abstract: We present in this article results on a new dissemination system of an ultrastable reference signal at 100 MHz on a standard fiber network. The 100 MHz signal is simply transferred by amplitude modulation of an optical carrier. Two different approaches for compensating the noise introduced by the link have been implemented. The limits of the two systems are analyzed and several solutions are suggested in order to improve the frequency stability and to further extend the distribution distance. Nevertheless, our system is a good tool for the best cold atom fountains comparison between laboratories, up to 100 km, with a relative frequency resolution of 10 −14 at 1 s integration time and 10 −17 for 1 day of measurement. The distribution system may be upgraded to fulfill the stringent distribution requirements for the future optical clocks.

Noise Properties of Superconducting Coplanar Waveguide Microwave Resonators

Abstract: We have measured noise in thin-film superconducting coplanar waveguide resonators. This noise appears entirely as phase noise, equivalent to a jitter of the resonance frequency. In contrast, amplitude fluctuations are not observed at the sensitivity of our measurement. The ratio between the noise power in the phase and amplitude directions is large, in excess of 30 dB. These results have important implications for resonant readouts of various devices such as detectors, amplifiers, and qubits. We suggest that the phase noise is due to two-level systems in dielectric materials.

Non-Gaussian low-frequency noise as a source of qubit decoherence.

Abstract: We study decoherence in a qubit with the distance between the two levels affected by random flips of bistable fluctuators. For the case of a single fluctuator we evaluate explicitly an exact expression for the phase-memory decay in the echo experiment with a resonant ac excitation. The echo signal as a function of time shows a sequence of plateaus. The position and the height of the plateaus can be used to extract the fluctuator switching rateand its coupling strength v. At small times the logarithm of the echo signal is / t 3 . The plateaus disappear when the decoherence is induced by many fluctuators. In this case the echo signal depends on the distribution of the fluctuators parameters. According to our analysis, the results significantly deviate from those obtained in the Gaussian model as soon as v * � . Introduction.—Quantum dynamics of two-level systems has recently attracted special attention in connection with ideas of quantum information processing. The central problem regarding operation of qubits and logical gates is maintaining the phase coherence in the presence of a noisy environment (1). At low temperatures the noise is dominated by discrete sources; it is caused by random charge exchange between localized states and electrodes in the Josephson (2) or semiconductor double quantum-dot qubits (3). The charge fluctuations are often modeled by a set of harmonic oscillators with certain frequency spectrum (4,5). In these ''spin-boson'' models the qubit decoherence is determined solely by the pair correlation function of random forces,SXf� , that implicitly assumes the noise to be Gaussian (6). This assumption, however, does not hold in most practical systems where SXf �/ 1=f and the processes have extremely broad distribution of the relaxa- tion times (7). To understand the role of the non-Gaussian statistics, we follow (8) and model the environment by a set of two-state systems (fluctuators) that randomly switch between their states. Their nonequilibrium dynamics can then be taken into account explicitly as was done in the analysis of coherent quantum transport in the presence of 1=f noise (9). Recent application of a similar approach to qubits demonstrated new features in the decoherence that are not reproduced in the Gaussian approximation (10). Quantum aspects of non-Markovian kinetics were ad- dressed in (11). In the present Letter we extend the work (10) in two directions. First, we evaluate explicitly the phase-memory decay in the echo experiment. We find a pronounced non- Gaussian behavior and explain plateaus observed in the time dependence of echo signal (2). Second, we consider the case where the interaction strengths between the qubit and fluctuators are broadly distributed. This distribution strongly modifies the time dependence and smears away the plateaus. We suggest a recipe for extracting the fluc- tuators' parameters from the measured echo signal. It is worth noting that a broad distribution of fluctuators' switching rates and the coupling strengths makes the prob- lem similar to the conventional models of the spectral diffusion in spin systems, structural glasses, and molecules embedded in a condensed phase (12-17). Model.—We assume that the qubit is a two-level system (TLS) surrounded by fluctuators—systems with two lo- cally stable states. Possible candidates for such fluctua- tors in solid state devices are charge traps, see Fig. 1, or structural dynamic defects. An occupied trap together with

Forward-looking radar GMTI benefits using a linear frequency diverse array

Abstract: The ability to suppress range ambiguous clutter is difficult for forward-looking arrays in GHTI processing. Use of linear frequency diverse array (FDA) is proposed, whereby each array channel operates at a different frequency and produces a range dependent pattern. The FDA significantly increases output signal-to-interference plus noise ratio (SINR) at the range ambiguous clutter Doppler, suggesting detection improvement. Output SINR is shown to increase by as much as 40 dB when compared to a constant frequency array.

Highly sensitive magnetometers—a review

Abstract: Conventional magnetic sensors, easy to use, are supposed to work mainly well over the nanotesla range, as due to the large magnetic environmental noise occurring in urban and industrial environments. On the other hand, a strange world exists, well below the nanotesla range, where the very efficient magnetic properties of superconducting materials have been used. It is the world investigated using cryogenic sensors, especially those of the SQUID's family. During a long time starting from the 1960s, SQUID people have refined their technologies, together with the use of advanced signal processing both analogue and digital, in order to input couple various external magnetic sources at room temperature, such the bio magnetic ones. State of the art of SQUID sensors is given. In the early 1990s, the dramatic improvement of the operating temperature led to the hope of lighter and lower costs systems with reduced cryogenic mount, designed to operate in open environment. An important target of multi SQUID systems using high critical temperature superconductors was and still is the magnetocardiography (MCG) mapping that could be daily used for improved diagnosis, as compared to conventional electrocardiography. It is known that such an important application is realistic only with noise spectral densities referred at the input lower than 100 fT/√Hz in a frequency bandwidth lying in between 1 Hz and 1 kHz and with a spatial resolution lower than 1 cm. The talk will review the recent advances in room temperature solid state sensors that could reach the above specified noise level. The review includes: magnetoresistive devices (AMR, GMR, spin valve, and spin dependent tunnelling device), Giant magneto-inductive devices. Non-solid, atomic vapor laser magnetometers, which have recently shown their ability to deliver very clear MCG signals, and start to be used to map the MCG signal above the chest just like SQUIDs systems, are reviewed. A simple, convenient energy resolution—volume is proposed, which allows a convenient way to compare high sensitivity magnetic sensors.

Diffusion of transcription factors can drastically enhance the noise in gene expression

Abstract: We study by simulation the effect of the diffusive motion of repressor molecules on the noise in mRNA and protein levels in the case of a repressed gene. We find that spatial fluctuations due to diffusion can drastically enhance the noise in gene expression. For a fixed repressor strength, the noise due to diffusion can be minimized by increasing the number of repressors or by decreasing the rate of the open complex formation. We also show that the effect of spatial fluctuations can be well described by a two-step kinetic scheme, where formation of an encounter complex by diffusion and the subsequent association reaction are treated separately. Our results also emphasize that power spectra are a highly useful tool for studying the propagation of noise through the different stages of gene expression.

Low-frequency current fluctuations in individual semiconducting single-wall carbon nanotubes.

Abstract: We present a systematic study on low-frequency current fluctuations of nanodevices consisting of one single semiconducting nanotube, which exhibit significant 1/f-type noise. By examining devices with different switching mechanisms, carrier types (electrons vs holes), and channel lengths, we show that the 1/f fluctuation level in semiconducting nanotubes is correlated to the total number of transport carriers present in the system. However, the 1/f noise level per carrier is not larger than that of most bulk conventional semiconductors, e.g., Si. The pronounced noise level observed in nanotube devices simply reflects on the small number of carriers involved in transport. These results not only provide the basis to quantify the noise behavior in a one-dimensional transport system but also suggest a valuable way to characterize low-dimensional nanostructures based on the 1/f fluctuation phenomenon.

Thermal noise from optical coatings in gravitational wave detectors.

Abstract: Gravitational waves are a prediction of Einstein's general theory of relativity. These waves are created by massive objects, like neutron stars or black holes, oscillating at speeds appreciable to the speed of light. The detectable effect on the Earth of these waves is extremely small, however, creating strains of the order of 10−21. There are a number of basic physics experiments around the world designed to detect these waves by using interferometers with very long arms, up to 4 km in length. The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth. Thermal noise arising from mechanical loss in the optical coatings put on the mirrors will be a significant source of noise. Achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties, is an area of active research right now.

Noise considerations in field-effect biosensors

Abstract: Field-effect sensors used to detect and identify biological species have been proposed as alternatives to other methods such as fluorescence deoxyribonucleic acid (DNA) microarrays. Sensors fabricated using commercial complementary metal-oxide-semiconductor technology would enable low-cost and highly integrated biological detection systems. In this paper, the small-signal and noise modeling of biosensors implemented with electrolyte-insulator-semiconductor structures is studied, with emphasis on design guidelines for low-noise performance. In doing so, a modified form of the general charge sheet metal-oxide-semiconductor field-effect transistor model that better fits the electrolyte-insulator-semiconductor structure is used. It is discussed how if the reference electrode and the insulator-electrolyte generate no noise associated with charge transport, then the main noise mechanisms are the resistive losses of the electrolyte and the low-frequency noise of the field-effect transistor. It is also found that...

Increasing threshold voltage variation due to random telegraph noise in FETs as gate lengths scale to 20 nm

Abstract: The statistical distribution of random telegraph noise (RTN) has been measured and characterized in scaled PDSOI FETs down to 20nm gate length. Statistical analysis of RTN in ≫ 15 thousand nFETs shows temperature-independent long-tailed non-Gaussian distributions of noise amplitudes. Treated as equivalent threshold voltage variation (ΔV th ), the RTN distributions appear log-normal, with the ΔV th reaching ≫ 70 mV for the smalles devices. Because of the log-normal distribution, it appears that RTN V th variations may exceed random dopant fluctuation (RDF) V th variations at the ∼3 sigma level in the 22 nm generation, making RTN a very serious threat to SRAM stability at 22 nm and beyond.

Estimating random errors due to shot noise in backscatter lidar observations

Abstract: We discuss the estimation of random errors due to shot noise in backscatter lidar observations that use either photomultiplier tube (PMT) or avalanche photodiode (APD) detectors. The statistical characteristics of photodetection are reviewed, and photon count distributions of solar background signals and laser backscatter signals are examined using airborne lidar observations at 532 nm using a photon-counting mode APD. Both distributions appear to be Poisson, indicating that the arrival at the photodetector of photons for these signals is a Poisson stochastic process. For Poisson- distributed signals, a proportional, one-to-one relationship is known to exist between the mean of a distribution and its variance. Although the multiplied photocurrent no longer follows a strict Poisson distribution in analog-mode APD and PMT detectors, the proportionality still exists between the mean and the variance of the multiplied photocurrent. We make use of this relationship by introducing the noise scale factor (NSF), which quantifies the constant of proportionality that exists between the root mean square of the random noise in a measurement and the square root of the mean signal. Using the NSF to estimate random errors in lidar measurements due to shot noise provides a significant advantage over the conventional error estimation techniques, in that with the NSF, uncertainties can be reliably calculated from or for a single data sample. Methods for evaluating the NSF are presented. Algorithms to compute the NSF are developed for the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations lidar and tested using data from the Lidar In-space Technology Experiment.

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

Abstract: 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

Contribution of thermal noise to frequency stability of rigid optical cavity via Hertz-linewidth lasers

Abstract: We perform detailed studies of state-of-the-art laser stabilization to high finesse optical cavities, revealing fundamental mechanical thermal noise-related length fluctuations. We compare the frequency noise of lasers tightly locked to the resonances of a variety of rigid Fabry-Perot cavities of differing lengths and mirror substrate materials. The results are in agreement with the theoretical model proposed in K. Numata, A. Kemery, and J. Camp [Phys. Rev. Lett. 93, 250602 (2004)]. The results presented here on the fundamental limits of FP references will impact planning and construction of next generation ultrastable optical cavities.

Power Converter EMI Analysis Including IGBT Nonlinear Switching Transient Model

Abstract: It is well known that very high dv/dt and di/dt during the switching instant is the major high-frequency electromagnetic interference (EMI) source. This paper proposes an improved and simplified EMI-modeling method considering the insulated gate bipolar transistor switching-behavior model. The device turn-on and turn-off dynamics are investigated by dividing the nonlinear transition by several stages. The real device switching voltage and current are approximated by piecewise linear lines and expressed using multiple dv/dt and di/dt superposition. The derived EMI spectra suggest that the high-frequency noise is modeled with an acceptable accuracy. The proposed methodology is verified by experimental results using a dc-dc buck converter

Mass detection with a nonlinear nanomechanical resonator.

Abstract: Nanomechanical resonators having small mass, high resonance frequency, and low damping rate are widely employed as mass detectors. We study the performance of such a detector when the resonator is driven into a region of nonlinear oscillations. We predict theoretically that in this region the system acts as a phase-sensitive mechanical amplifier. This behavior can be exploited to achieve noise squeezing in the output signal when homodyne detection is employed for readout. We show that mass sensitivity of the device in this region may exceed the upper bound imposed by thermomechanical noise upon the sensitivity when operating in the linear region. On the other hand, we show that the high mass sensitivity is accompanied by a slowing down of the response of the system to a change in the mass.

Adsorption–desorption noise in gas sensors: Modelling using Langmuir and Wolkenstein models for adsorption

Abstract: A comparison between adsorption–desorption (A–D) noise models obtained using Langmuir and Wolkenstein theories is presented. This noise is generated by instantaneous fluctuations in the number of the adsorbed molecules, which cause free electron's density fluctuations in the sensing layer, and consequently a fluctuation in the conductance of the gas sensor. Both isotherms lead to a Lorentzian contribution of adsorption–desorption noise with the same cut-off frequency. The noise spectrum obtained using Wolkentein adsorption theory has a low frequency magnitude which is greater than that of the spectrum obtained using Langmuir theory. With both models the power density spectrum (PDS) of the fluctuation of the sensor's conductance has a cut-off frequency and low frequency magnitude which are specifics of the adsorbed gas. This result confirms that noise spectroscopy could be a useful tool for extracting information on the nature of the detected gas.

Noise figure optimization of inductively degenerated CMOS LNAs with integrated gate inductors

Abstract: This paper discusses noise figure optimization techniques for inductively degenerated cascode CMOS low-noise amplifiers (LNAs) with on-chip gate inductors. Seven different optimizations techniques are discussed. Of these, five new cases provide power match and balance the transistor noise contribution and the noise contribution from all parasitic resistances in the gate circuit to achieve the best noise performance under the constraints of integrated gate inductor quality factor, power consumption, and gain. Three of the power matched techniques (two power constrained optimizations and a gain-and-power constrained optimization) are recommended as design strategies. These three optimization techniques significantly improve the noise figures for LNA designs that are to employ on-chip gate inductors.

Compact Noise Models for MOSFETs

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