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Showing papers on "Noise (electronics) published in 2008"


Journal ArticleDOI
TL;DR: It is shown that a CS-stage with deep submicron transistors can have high IIP2, because the nugsldr nuds cross-term in a two-dimensional Taylor approximation of the IDS(VGS, VDS) characteristic can cancel the traditionally dominant square-law term in the IDs(V GS) relation at practical gain values.
Abstract: An inductorless low-noise amplifier (LNA) with active balun is proposed for multi-standard radio applications between 100 MHz and 6 GHz. It exploits a combination of a common-gate (CGH) stage and an admittance-scaled common-source (CS) stage with replica biasing to maximize balanced operation, while simultaneously canceling the noise and distortion of the CG-stage. In this way, a noise figure (NF) close to or below 3 dB can be achieved, while good linearity is possible when the CS-stage is carefully optimized. We show that a CS-stage with deep submicron transistors can have high IIP2, because the nugsldr nuds cross-term in a two-dimensional Taylor approximation of the IDS(VGS, VDS) characteristic can cancel the traditionally dominant square-law term in the IDS(VGS) relation at practical gain values. Using standard 65 nm transistors at 1.2 V supply voltage, we realize a balun-LNA with 15 dB gain, NF +20 dBm, while simultaneously achieving an IIP3 > 0 dBm. The best performance of the balun is achieved between 300 MHz to 3.5 GHz with gain and phase errors below 0.3 dB and plusmn2 degrees. The total power consumption is 21 mW, while the active area is only 0.01 mm2.

579 citations


Journal ArticleDOI
Yu-Ming Lin1, Phaedon Avouris1
TL;DR: The noise characteristics of single-layer and bilayer graphene nanodevices are investigated and an unexpected 1/f noise behavior for bilayer devices is uncovered, pointing to exciting opportunities for graphene bilayers in low-noise applications.
Abstract: Low-frequency 1/f noise is ubiquitous and dominates the signal-to-noise performance in nanodevices. Here we investigate the noise characteristics of single-layer and bilayer graphene nanodevices and uncover an unexpected 1/f noise behavior for bilayer devices. Graphene is a single layer of graphite, where carbon atoms form a two-dimensional (2D) honeycomb lattice. Despite the similar composition, bilayer graphene (two graphene monolayers stacked in the natural graphite order) is a distinct 2D system with a different band structure and electrical properties. 1,2 In graphene monolayers, the 1/f noise is found to follow Hooge’s empirical relation with a noise parameter comparable to that of bulk semiconductors. However, this 1/f noise is strongly suppressed in bilayer graphene devices and exhibits an unusual dependence on the carrier density, different from most other materials. The unexpected noise behavior in graphene bilayers is associated with its unique band structure that varies with the charge distribution among the two layers, resulting in an effective screening of potential fluctuations due to external impurity charges. The findings here point to exciting opportunities for graphene bilayers in low-noise applications.

402 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate two regeneration schemes using low-power four-wave mixing in a silicon nanowaveguide and compensate for the effects of poor extinction ratio, dispersive broadening and timing jitter.
Abstract: To meet the increasing demand for higher capacity in optical communications, signal transmission at higher modulation rates and over a broader wavelength range will be required. Signal degradation in the optical channel caused by dispersion, nonlinearity and noise becomes a critical issue as data rates increase. Thus, it is highly desirable to develop broadband, high-speed regeneration devices1. Recent advances in silicon-on-insulator photonic devices offer the potential for highly integrated, robust opto–electronic architectures, and optical processes such as amplification2,3,4, wavelength conversion5,6,7 and amplitude modulation8,9 have already been demonstrated in such structures. In this work, we demonstrate two regeneration schemes using low-power four-wave mixing in a silicon nanowaveguide and compensate for the effects of poor extinction ratio, dispersive broadening and timing jitter. This capability further expands the range of optical functions that can be incorporated into silicon-compatible photonic devices offering a broadband and integrated solution for regeneration.

399 citations


Journal ArticleDOI
TL;DR: The signal-to-noise ratio for DNA translocation for different salt concentrations and nanopore diameters is computed, yielding the parameters for optimal detection efficiency.
Abstract: We study ionic current fluctuations in solid-state nanopores over a wide frequency range and present a complete description of the noise characteristics. At low frequencies (f approximately 1 kHz), we can model the increase in current power spectral density with frequency through a calculation of the Johnson noise. Finally, we use these results to compute the signal-to-noise ratio for DNA translocation for different salt concentrations and nanopore diameters, yielding the parameters for optimal detection efficiency.

360 citations


Journal ArticleDOI
TL;DR: In this paper, theoretical predictions and experimental measurements for the achievable phase noise, timing jitter, and frequency stability in the coherent transport of an optical frequency over a fiber-optic link are discussed.
Abstract: We present theoretical predictions and experimental measurements for the achievable phase noise, timing jitter, and frequency stability in the coherent transport of an optical frequency over a fiber-optic link. Both technical and fundamental limitations to the coherent transfer are discussed. Measurements of the coherent transfer of an optical carrier over links ranging from 38 to 251 km demonstrate good agreement with theory. With appropriate experimental design and bidirectional transfer on a single optical fiber, the frequency instability at short times can reach the fundamental limit imposed by delay-unsuppressed phase noise from the fiber link, yielding a frequency instability that scales as link length to the 3/2 power. For two-way transfer on separate outgoing and return fibers, the instability is severely limited by differential fiber noise.

330 citations


01 Jan 2008
TL;DR: Two efficient quantum key distribution schemes over two different collective-noise channels are presented and the receiver is only required to perform single-particle product measurements and there is no basis mismatch.

320 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate potential sources of measurement errors and compare them with the scientific requirements for a direct detection CO2 system operating at 1.6μm, 0.4% for CO2 at 2.1μm and 0.3% for CH4 at 3.9μm.
Abstract: CO2, CH4, and N2O are recognised as the most important greenhouse gases, the concentrations of which increase rapidly through human activities. Space-borne integrated path differential absorption lidar allows global observations at day and night over land and water surfaces in all climates. In this study we investigate potential sources of measurement errors and compare them with the scientific requirements. Our simulations reveal that moderate-size instruments in terms of telescope aperture (0.5–1.5 m) and laser average power (0.4–4 W) potentially have a low random error of the greenhouse gas column which is 0.2% for CO2 and 0.4% for CH4 for soundings at 1.6 μm, 0.4% for CO2 at 2.1 μm, 0.6% for CH4 at 2.3 μm, and 0.3% for N2O at 3.9 μm. Coherent detection instruments are generally limited by speckle noise, while direct detection instruments suffer from high detector noise using current technology. The wavelength selection in the vicinity of the absorption line is critical as it controls the height region of highest sensitivity, the temperature cross-sensitivity, and the demands on frequency stability. For CO2, an error budget of 0.08% is derived from our analysis of the sources of systematic errors. Among them, the frequency stability of ± 0.3 MHz for the laser transmitter and spectral purity of 99.9% in conjunction with a narrow-band spectral filter of 1 GHz (FWHM) are identified to be challenging instrument requirements for a direct detection CO2 system operating at 1.6 μm.

303 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate the noise characteristics of single-layer and bilayer graphene nano-devices, and uncover an unexpected 1/f noise behavior for bilayer devices.
Abstract: Low-frequency 1/f noise is ubiquitous, and dominates the signal-to-noise performance in nanodevices. Here we investigate the noise characteristics of single-layer and bilayer graphene nano-devices, and uncover an unexpected 1/f noise behavior for bilayer devices. Graphene is a single layer of graphite, where carbon atoms form a 2D honeycomb lattice. Despite the similar composition, bilayer graphene (two graphene monolayers stacked in the natural graphite order) is a distinct 2D system with a different band structure and electrical properties. In graphene monolayers, the 1/f noise is found to follow Hooge's empirical relation with a noise parameter comparable to that of bulk semiconductors. However, this 1/f noise is strongly suppressed in bilayer graphene devices, and exhibits an unusual dependence on the carrier density, different from most other materials. The unexpected noise behavior in graphene bilayers is associated with its unique band structure that varies with the charge distribution among the two layers, resulting in an effective screening of potential fluctuations due to external impurity charges. The findings here point to exciting opportunities for graphene bilayers in low-noise applications.

302 citations


Journal ArticleDOI
TL;DR: A time-domain analysis is proposed that accounts for the time varying nature of the circuit exploiting some basic results from the solution of stochastic differential equations and the resulting symbolic expressions allow focusing designers' attention on the most influential noise contributors.
Abstract: The need for highly integrable and programmable analog-to-digital converters (ADCs) is pushing towards the use of dynamic regenerative comparators to maximize speed, power efficiency and reconfigurability. Comparator thermal noise is, however, a limiting factor for the achievable resolution of several ADC architectures with scaled supply voltages. While mismatch in these comparators can be compensated for by calibration, noise can irreparably hinder performance and is less straightforward to be accounted for at design time. This paper presents a method to estimate the input referred noise in fully dynamic regenerative comparators leveraging a reference architecture. A time-domain analysis is proposed that accounts for the time varying nature of the circuit exploiting some basic results from the solution of stochastic differential equations. The resulting symbolic expressions allow focusing designers' attention on the most influential noise contributors. Analysis results are validated by comparison with electrical simulations and measurement results from two ADC prototypes based on the reference comparator architecture, implemented in 0.18-mum and 90-nm CMOS technologies.

277 citations


Posted Content
TL;DR: New, improved outer bounds on the capacity region are developed and it is shown that treating interference as noise achieves the sum capacity of the two-user Gaussian interference channel in a low-interference regime, where the interference parameters are below certain thresholds.
Abstract: Establishing the capacity region of a Gaussian interference network is an open problem in information theory. Recent progress on this problem has led to the characterization of the capacity region of a general two user Gaussian interference channel within one bit. In this paper, we develop new, improved outer bounds on the capacity region. Using these bounds, we show that treating interference as noise achieves the sum capacity of the two user Gaussian interference channel in a low interference regime, where the interference parameters are below certain thresholds. We then generalize our techniques and results to Gaussian interference networks with more than two users. In particular, we demonstrate that the total interference threshold, below which treating interference as noise achieves the sum capacity, increases with the number of users.

251 citations


DissertationDOI
01 Jan 2008
TL;DR: In this article, the authors explored the properties of microwave kinetic inductance detectors (MKID) and their properties of excess frequency noise, including power, temperature, material, and geometry dependence.
Abstract: Over the past decade, low temperature detectors have brought astronomers revolutionary new observational capabilities and led to many great discoveries. Although a single low temperature detector has very impressive sensitivity, a large detector array would be much more powerful and are highly demanded for the study of more difficult and fundamental problems in astronomy. However, current detector technologies, such as transition edge sensors and superconducting tunnel junction detectors, are difficult to integrate into a large array. The microwave kinetic inductance detector (MKID)is a promising new detector technology invented at Caltech and JPL which provides both high sensitivity and an easy solution to the detector integration. It senses the change in the surface impedance of a superconductor as incoming photons break Cooper pairs, by using high-Q superconducting microwave resonators capacitively coupled to a common feedline. This architecture allows thousands of detectors to be easily integrated through passive frequency domain multiplexing. In this thesis, we explore the rich and interesting physics behind these superconducting microwave resonators. The first part of the thesis discusses the surface impedance of a superconductor, the kinetic inductance of a superconducting coplanar waveguide, and the circuit response of a resonator. These topics are related with the responsivity of MKIDs. The second part presents the study of the excess frequency noise that is universally observed in these resonators. The properties of the excess noise, including power, temperature, material, and geometry dependence, have been quantified. The noise source has been identified to be the two-level systems in the dielectric material on the surface of the resonator. A semi-empirical noise model has been developed to explain the power and geometry dependence of the noise, which is useful to predict the noise for a specified resonator geometry. The detailed physical noise mechanism, however, is still not clear. With the theoretical results of the responsivity and the semi-empirical noise model established in this thesis, a prediction of the detector sensitivity (noise equivalent power) and an optimization of the detector design are now possible.

Journal ArticleDOI
TL;DR: The statistical distribution of background noise was analyzed for MR acquisitions with a single-channel and a 32-channel coil, with sum-of-squares (SoS) and spatial-matched-filter (SMF) data combination, with and without parallel imaging using k-space and image-domain algorithms, with real-part and conventional magnitude reconstruction and with several reconstruction filters.

Proceedings ArticleDOI
01 Feb 2008
TL;DR: SAR architectures have been recently demonstrated as able to achieve high power efficiency in the moderate-resolution/medium- bandwidth range, but when the comparator determines in first instance the overall performance, comparator thermal noise can limit the maximum achievable resolution.
Abstract: Current trends in analog/mixed-signal design for battery-powered devices demand the adoption of cheap and power-efficient ADCs. SAR architectures have been recently demonstrated as able to achieve high power efficiency in the moderate-resolution/medium- bandwidth range in Craninckx, J. and Van der Plas, G., (2007). However, when the comparator determines in first instance the overall performance, as in most SAR ADCs, comparator thermal noise can limit the maximum achievable resolution. More than 1 and 2 ENOB reductions are observed in Craninckx, J. and Van der Plas, G., (2007) and Kuttner, F., (2002), respectively, because of thermal noise, and degradations could be even worse with scaled supply voltages and the extensive use of dynamic regenerative latches without pre-amplification. Unlike mismatch, random noise cannot be compensated by calibration and would finally demand a quadratic increase in power consumption unless alternative circuit techniques are devised.

Journal ArticleDOI
TL;DR: In this paper, the Kirton and Uren model has been used to analyze the power density of the mobility noise in submicrometer MOSTs and the results of their computer simulations have been shown to be ldquosubstantially different from the usual 1/ tau distribution.
Abstract: 1/f noise is a fluctuation in the conductance of semiconductors and metals. This noise could be a fluctuation in the number of free electrons or in their mobility. Many experimental studies have proved that the 1/f noise in homogeneous samples is a fluctuation in the mobility. There is a reliable empirical relation for the power density of the mobility noise. Theoretical models for mobility noise have not had much influence in the discussions. The theoretical position for number fluctuations is quite the opposite. The generally accepted McWhorter model is simple; however, very few experimental studies definitely prove number fluctuations and exclude uncorrelated mobility fluctuations. There is an extensive literature on noise in MOSTs. Submicrometer MOSTs are notorious for their high low-frequency noise. Almost all studies start from the McWhorter generation-recombination (GR) model. The discussion is confused by the many complications of the MOSTs, such as mobility degradation, surface and contacts effects, size of the samples, etc. An additional problem is that the real 1/f noise is often mixed up with other types of low-frequency noise, such as burst and GR noises. A critical discussion is given for the Kirton and Uren model. Analytical expressions are presented for the results of their computer simulations. This explains their surprising discovery that the density of McWhorter states may be ldquosubstantiallyrdquo different from the usual 1/ tau distribution.

Journal ArticleDOI
TL;DR: This work uses a smaller noise reduction inductor compared with the conventional inductor based technique to reduce the noise and the nonlinearity influences of the cascode transistors in a differential cascode CS-LNA.
Abstract: A typical common source cascode low-noise amplifier (CS-LNA) can be treated as a CS-CG two stage amplifier. In the published literature, an inductor is added at the drain of the main transistor to reduce the noise contribution of the cascode transistors. In this work, an inductor connected at the gate of the cascode transistor and capacitive cross-coupling are strategically combined to reduce the noise and the nonlinearity influences of the cascode transistors in a differential cascode CS-LNA. It uses a smaller noise reduction inductor compared with the conventional inductor based technique. It can reduce the noise, improve the linearity and also increase the voltage gain of the LNA. The proposed technique is theoretically formulated. Furthermore, as a proof of concept, a 2.2 GHz inductively degenerated CS-LNA was fabricated using TSMC 0.35 mum CMOS technology. The resulting LNA achieves 1.92 dB noise figure, 8.4 dB power gain, better than 13 dB S11, more than 30 dB isolation (S12), and -2.55 dBm IIP3, with the core fully differential LNA consuming 9 mA from a 1.8 V power supply.

Proceedings ArticleDOI
22 Sep 2008
TL;DR: A new algorithm for estimating the signal-to-noise ratio (SNR) of speech signals, called WADA-SNR (Waveform Amplitude Distribution Analysis) is introduced, which shows significantly less bias and less variability with respect to the type of noise compared to the standard NIST STNR algorithm.
Abstract: In this paper, we introduce a new algorithm for estimating the signal-to-noise ratio (SNR) of speech signals, called WADA-SNR (Waveform Amplitude Distribution Analysis) In this algorithm we assume that the amplitude distribution of clean speech can be approximated by the Gamma distribution with a shaping parameter of 04, and that an additive noise signal is Gaussian Based on this assumption, we can estimate the SNR by examining the amplitude distribution of the noise-corrupted speech We evaluate the performance of the WADA-SNR algorithm on databases corrupted by white noise, background music, and interfering speech The WADA-SNR algorithm shows significantly less bias and less variability with respect to the type of noise compared to the standard NIST STNR algorithm In addition, the algorithm is quite computationally efficient Index Terms : SNR estimation, Gamma distribution, Gaussian distribution 1 Introduction The estimation of signal-to-noise ratios (SNRs) has been extensively investigated for decades and it is still an active field of research (

Journal ArticleDOI
TL;DR: New and concise descriptors of the residual density are presented, namely the gross residual electrons, the net residual electrons and the fractal dimension distribution, which can in principle also be applied to space and momentum residual densities in a one-, two-, three- or higher-dimensional Euclidean space.
Abstract: New and concise descriptors of the residual density are presented, namely the gross residual electrons, the net residual electrons and the fractal dimension distribution. These descriptors indicate how much residual density is present and in what way it is distributed, i.e. the extent to which the distribution is featureless. The amount of residual density present accounts for noise in the experimental data as well as for modeling inadequacies. Therefore, the minimization of the gross residual electrons during refinement serves as a quality criterion. In the case where only Gaussian noise is present in the residual density, the fractal distribution is parabolic in shape. Deviations from this shape therefore serve as an indicator for systematic errors. The new measures have been applied to simulated and experimental data in order to study the effects of noise, model inadequacies and truncation in the experimental resolution. These measures, although designed and examined with particular regard to applications of space residual density, are very general and can in principle also be applied to space and momentum residual densities in a one-, two-, three- or higher-dimensional Euclidean space.

Journal ArticleDOI
TL;DR: In this paper, a series of results that push the limits of optical sensing, acceleration sensing and lithography were demonstrated, including optical nano-grating accelerometers with resonant frequencies as low as 36 Hz and thermal noise floors corresponding to 8 nG/s2.
Abstract: We have successfully demonstrated a series of results that push the limits of optical sensing, acceleration sensing and lithography. Previously, we built some of the most sensitive displacement sensors with displacement sensitivities as low as 12 fm / Hz at 1 kHz. Using reference detection circuitry in conjunction with correlated double sampling methods, we lowered the 1/f noise floor to 10 mHz, hence improving the detection limit at low frequencies (10 mHz) by 77 dB to 50 fm / Hz . We converted these highly sensitive displacement sensors to highly sensitive acceleration sensors through a direct mass integration processes. Our accelerometers have resonant frequencies as low as 36 Hz and thermal noise floors as low as 8 nG / Hz (where 1 G = 9.8 m/s2). We have pushed the limits of shaker table experiments to independently verify acceleration measurements as low as 10 μ G / Hz . Direct measurements with our integrated sub-wavelength optical nano-grating accelerometers have shown device sensitivities of 590 V/G and noise floors corresponding to 17 nG / Hz (at 1 Hz).

Journal ArticleDOI
TL;DR: In this paper, a simple bilayer deposition route, combining photolithography with focused ion beam patterning, produces high performance nanoscale superconducting quantum interference devices (SQUIDs) with magnetic flux sensitivity of around 0.2μΦ0∕Hz1∕2.
Abstract: Science and industry demand ever more sensitive measurements on ever smaller systems, as exemplified by spintronics, nanoelectromechanical system, and spin-based quantum information processing, where single electronic spin detection poses a grand challenge. Superconducting quantum interference devices (SQUIDs) have yet to be effectively applied to nanoscale measurements. Here, we show that a simple bilayer deposition route, combining photolithography with focused ion beam patterning, produces high performance nanoscale SQUIDs. We present results of noise measurements on these nanoSQUIDs which correspond to a magnetic flux sensitivity of around 0.2μΦ0∕Hz1∕2. This represents one of the lowest noise values achieved for a SQUID device operating above 1K.

Journal ArticleDOI
TL;DR: In this article, a mean field approach is proposed for the analysis of orientational order in a two-dimensional system of stochastic self-propelled particles interacting by local velocity alignment mechanism.
Abstract: A mean-field approach (MFA) is proposed for the analysis of orientational order in a two-dimensional system of stochastic self-propelled particles interacting by local velocity alignment mechanism. The treatment is applied to the cases of ferromagnetic (F) and liquid-crystal (LC) alignment. In both cases, MFA yields a second order phase transition for a critical noise strength and a scaling exponent of 1/2 for the respective order parameters. We find that the critical noise amplitude ηc at which orientational order emerges in the LC case is smaller than in the F-alignment case, i.e. ηLC C<ηF C. A comparison with simulations of individual-based models with F- resp. LC-alignment shows that the predictions about the critical behavior and the qualitative relation between the respective critical noise amplitudes are correct.

Journal ArticleDOI
TL;DR: In this paper, a simple but realistic estimate of the frequency uncertainty in time series analyses is presented, where the error is defined as a function of the relative level of noise, signal and frequency difference.
Abstract: Context: Several approaches to estimate frequency, phase and amplitude errors in time series analyses were reported in the literature, but they are either time consuming to compute, grossly overestimating the error, or are based on empirically determined criteria. Aims: A simple, but realistic estimate of the frequency uncertainty in time series analyses. Methods: Synthetic data sets with mono- and multi-periodic harmonic signals and with randomly distributed amplitude, frequency and phase were generated and white noise added. We tried to recover the input parameters with classical Fourier techniques and investigated the error as a function of the relative level of noise, signal and frequency difference. Results: We present simple formulas for the upper limit of the amplitude, frequency and phase uncertainties in time-series analyses. We also demonstrate the possibility to detect frequencies which are separated by less than the classical frequency resolution and that the realistic frequency error is at least 4 times smaller than the classical frequency resolution.

Journal ArticleDOI
TL;DR: The design and measurement results of millimeter-wave integrated circuits implemented in 65-nm baseline CMOS, including an on-chip spiral balun, and the transition from CPW to the balun and transistor noise parameter measurement results at V-band are presented.
Abstract: We present the design and measurement results of millimeter-wave integrated circuits implemented in 65-nm baseline CMOS. Both active and passive test structures were measured. In addition, we present the design of an on-chip spiral balun and the transition from CPW to the balun and report transistor noise parameter measurement results at V-band. Finally, the design and measurement results of two amplifiers and a balanced resistive mixer are presented. The 40-GHz amplifier exhibits 14.3 dB of gain and the 1-dB output compression point is at +6-dBm power level using a 1.2 V supply with a compact chip area of 0.286 mm2. The 60-GHz amplifier achieves a measured noise figure of 5.6 dB at 60 GHz. The AM/AM and AM/PM results show a saturated output power of +7 dBm using a 1.2 V supply. In downconversion, the balanced resistive mixer achieves 12.5 dB of conversion loss and +5 dBm of 1-dB input compression point. In upconversion, the measured conversion loss was 13.5 dB with -19 dBm of 1-dB output compression point.

Journal ArticleDOI
TL;DR: Experimental results overcome the standard quantum limit shot-noise level without subtraction of the variance of the detection noise.
Abstract: We have measured sub-shot-noise quantum correlations of spatial fluctuations in the far-field image of the parametric fluorescence created in a type I beta-barium-borate nonlinear crystal. Imaging is performed at very low light level (0.15 photons per pixel) with an electron multiplying charge coupled device camera. Experimental results overcome the standard quantum limit shot-noise level without subtraction of the variance of the detection noise.

Journal ArticleDOI
TL;DR: In this paper, thermal fluctuations in the coatings used to make high reflectors are becoming significant noise sources in precision optical measurements and are particularly relevant to advanced gravitational-wave detectors.
Abstract: Thermal fluctuations in the coatings used to make high reflectors are becoming significant noise sources in precision optical measurements and are particularly relevant to advanced gravitational-wave detectors. There are two recognized sources of coating thermal noise; mechanical loss and thermal dissipation. Thermal dissipation causes thermal fluctuations in the coating which produce noise via the thermoelastic and thermorefractive mechanisms. We treat these mechanisms coherently, give a correction for finite coating thickness, and evaluate the implications for Advanced LIGO.

Journal ArticleDOI
TL;DR: Analysis of performance measurements from a MIMO-OFDM IEEE 802.11n hardware implementation using four transmitters and four receivers shows that the measured results do not align with standard prediction based on simulation assuming uncorrelated receiver noise, and can be explained by the inclusion of transmitter noise into the channel model.
Abstract: This paper presents analysis of performance measurements from a MIMO-OFDM IEEE 802.11n hardware implementation at 5.2 GHz using four transmitters and four receivers. Two spatial multiplexing systems are compared; one which uses a zero-forcing (ZF) detector and the other a list sphere detector (LSD). We show that the measured results do not align with standard prediction based on simulation assuming uncorrelated receiver noise. We show that the discrepancy can be explained by the inclusion of transmitter noise into the channel model. This effect is not included in existing MIMO-OFDM channel models. The measured results from our hardware implementation show successful packet transmission at 600 Mb/s with 15 bits/s/Hz spectral efficiency at 73% coverage for ZF and 84% coverage for LSD with an average receiver signal to noise ratio (SNR) of 26 dB.

Journal ArticleDOI
TL;DR: In this article, a probabilistic superposition of elementary Markov processes describing the trapping/detrapping events taking place in the cell tunnel oxide was proposed to explain the main features of the random telegraph noise threshold-voltage instability.
Abstract: This paper presents a new physics-based statistical model for random telegraph noise in Flash memories. From the probabilistic superposition of elementary Markov processes describing the trapping/detrapping events taking place in the cell tunnel oxide, the model can explain the main features of the random telegraph noise threshold-voltage instability. The results on the statistical distribution of the threshold-voltage difference between two subsequent read accesses show good agreement between measurements and model predictions, even considering the time drift of the distribution tails. Moreover, the model gives a detailed spectroscopic analysis of the oxide defects responsible for the random telegraph noise, allowing a spatial and energetic localization of the traps involved in the threshold-voltage instability process.

Journal ArticleDOI
TL;DR: By exploiting Raman amplification with an incoherent pump, the amplified signal is shown to develop a series of temporal intensity spikes whose peak power follows a power-law probability distribution.
Abstract: We report experimental observation and characterization of rogue wave-like extreme value statistics arising from pump-signal noise transfer in a fiber Raman amplifier. Specifically, by exploiting Raman amplification with an incoherent pump, the amplified signal is shown to develop a series of temporal intensity spikes whose peak power follows a power-law probability distribution. The results are interpreted using a numerical model of the Raman gain process using coupled nonlinear Schrodinger equations, and the numerical model predicts results in good agreement with experiment.

Journal ArticleDOI
TL;DR: In this paper, a monolithically integrated CMOS-MEMS three-axis capacitive accelerometer with a single proof mass was developed, which provided robust single-crystal silicon (SCS) structures in all three axes and greatly reduced undercut of comb fingers.
Abstract: This paper reports a monolithically integrated CMOS-MEMS three-axis capacitive accelerometer with a single proof mass. An improved DRIE post-CMOS MEMS process has been developed, which provides robust single-crystal silicon (SCS) structures in all three axes and greatly reduces undercut of comb fingers. The sensing electrodes are also composed of the thick SCS layer, resulting in high resolution and large sensing capacitance. Due to the high wiring flexibility provided by the fabrication process, fully differential capacitive sensing and common-centroid configurations are realized in all three axes. A low-noise, low- power dual-chopper amplifier is designed for each axis, which consumes only 1 mW power. With 44.5 dB on-chip amplification, the measured sensitivities of x-, y-, and z-axis accelerometers are 520 mV/g, 460 mV/g, and 320 mV/g, respectively, which can be tuned by simply changing the amplitude of the modulation signal. Accordingly, the overall noise floors of the x-, y-, and z-axis are 12 mug/radicHz , 14 mug/radicHz, and 110 mug/radicHz, respectively, when tested at around 200 Hz.

Journal ArticleDOI
TL;DR: In this paper, a simple, but realistic, estimate of the frequency uncertainty in time-series analyses is presented, which is based on a simple formula for the upper limit of the amplitude, frequency, and phase uncertainties.
Abstract: Context. Several approaches to estimating frequency, phase, and amplitude errors in time-series analyse have been reported in the literature, but they are either time-consuming to compute, grossly overestimating the error, or are based on empirically determined criteria.Aims. A simple, but realistic estimate of the frequency uncertainty in time-series analyses is our goal here.Methods. Synthetic data sets with mono- and multi-periodic harmonic signals and with randomly distributed amplitude, frequency, and phase were generated and white noise added. We tried to recover the input parameters with classical Fourier techniques and investigated the error as a function of the relative level of noise, signal, and frequency difference.Results. We present simple formulas for the upper limit of the amplitude, frequency, and phase uncertainties in time-serie analyses. We also demonstrate the possibility of detecting frequencies that are separated by less than the classical frequency resolution and of finding that the realistic frequency error is at least 4 times smaller than the classical frequency resolution.

Journal ArticleDOI
TL;DR: The statistical properties of the transfer function between two points in the power distribution system are deduced from a propagation model that takes into account the complicated structure of the cable bundles.
Abstract: In this paper, we address the problem of power line communication inside a vehicle, focusing on channel characterization and modeling. The statistical properties of the transfer function between two points in the power distribution system are deduced from a propagation model that takes into account the complicated structure of the cable bundles. Theoretical estimates are compared to experimental results. Later on, this theoretical model, together with an impulsive noise model, will be implemented in a software communication tool that is designed to optimize modulation schemes and channel coding.