High Frequency Noise Modeling Research Articles

High frequency noise model based on statistical energy method parameter sensitivity analysis

According to the basic principle of statistical energy method, the high frequency SEA model of the full vehicle is established. Through the comparison of simulation and test results, the error of power based noise reduction (PBNR) and interior sound pressure level response is less than three dB, which proves the accuracy of high frequency simulation model. Through the design of different schemes, the sensitivity analysis of parameters such as material parameters, internal loss factor and leakage rate to the model is obtained. The research results show that the accuracy of material parameters, internal loss factor and leakage rate can improve the accuracy of high-frequency simulation model. The sensitivity analysis can provide some ideas for vehicle high frequency noise model adjustment and modification.

High-Frequency Noise Characterization and Modeling of Graphene Field-Effect Transistors

This article presents the small-signal and noise characterization of different technologies based on chemical vapor deposition (CVD) and silicon-carbide (SiC) graphene field-effect transistors (GFETs). The noise model, built on noise figure measurements under $50~\Omega $ using the F50 method, was verified by additional source-pull measurements, with special care for the GFET stability. The four noise parameters were then extracted by using the validated F50 model up to 18 GHz, and the correlations between noise and small-signal parameters were shown for two different configurations: top-gated and back-gated GFETs.

High-Frequency Noise Characterization and Modeling of SiGe HBTs

For heterojunction bipolar transistors (HBTs), the noise correlation influences the noise parameters and is therefore relevant for transistor modeling, especially at sufficiently high frequencies. In order to predict the noise correlation, it is necessary to determine the noise transit time in the noise transport model. In this paper, the noise correlation and noise transit time are predicted from the high current model without measured noise data. The four noise parameters are calculated based on the predicted noise transit time and the Y-parameter noise calculation methodology. The extracted noise transit time is validated by the measured result over bias and temperature, which is determined by fitting NFmin of the silicon-germanium (SiGe) HBT between Y-parameter noise calculation methodology and tuner-based noise measurement. It was found that the noise transit time is independent of frequency but dependent on bias and temperature. Also, the results indicate that the calculated four noise parameters based on the extracted noise transit time have a good agreement with the tuner-based noise measurement.

High Frequency Noise Model of AlGaN/GaN HEMTs

Compared with conventional GaAs HEMTs, the larger gate leakage current and more obviously self-heating effects are two unique macroscopic features in AlGaN/GaN HEMTs. This paper presents the study of the effects brought by temperature-dependent Rs and Rd on noise performance of AlGaN/GaN HEMT. Based on these studies, a noise model up to 35GHz is established. An improved PRC model is proposed and the noise parameters NFmin, Rn and Γopt in the frequency band ranging from 0.1GHz to 35GHz is investigated. The effects brought by gate leakage current have been taken into consideration. Then, noise performance under different ambient temperature has been studied based on the high frequency noise model mentioned above. The parameters in the model except the parasitic inductors and capacitors are all temperature-dependent. With the model, the effects brought by temperature-dependent Rs and Rd have been studied under four different temperatures by comparing the noise performance in two different conditions. Results show that the temperature-dependent characteristics of these two parasitic resistances will have an effect on NFmin and Rn while little effect on Γopt.

Frequency and bias dependent modeling of induced gate noise and cross-correlation noise in 40 nm metal-oxide-semiconductor field-effect transistors

With the development of down-scaling of CMOS technology for low power, mixed-signal, and high frequency applications, the optimal high frequency performance is shown to be shifted from lower moderate inversion toward weak inversion regimes. High-frequency noise model is a prerequisite for designing the radio frequency and millimeter-wave circuits, and is essential for the noise analysis of nanoscale metal-oxide-semiconductor field-effect transistors (MOSFETs). In this paper, based on the physical structure of 40 nm MOSFET and by considering the drift-diffusion equation and charge conservation law, accurate physics-based unified high-frequency noise model is developed for induced gatecurrent noise and its cross-correlation with drain-current noise under different bias conditions, which is used to describe the frequency and bias dependence of 40 nm MOSFET from weak inversion to strong inversion regime. Especially, the effective gate overdrive is explicitly included in unified noise model to offer excellent accuracy, continuity and smoothness, and this makes the proposed analytical models convenient to directly reflect the relationship between the noise model and bias condition. Besides, new analytical model is derived for the induced-gate current noise and its cross-correlation term of weakly inverted MOSFET. These simple expressions not only serve as the asymptotic limit for the validation of the proposed physics-based unified model, but also provide a clearer insight into and better understanding of the gate noise behavior and their cross-correlation in the weak-inversion region. Moreover, in terms of the proposed subthreshold noise model, the charge of weak inversion rather than the normal effective channel thickness approximation is involved. In this way, the model accuracy can be improved. Furthermore, a detailed derivation and discussion are presented by analyzing the physics-based noise generation mechanism of transistor including the channel thermal noise and the shot noise based on the small-signal equivalent circuit of the 40 nm MOSFET device. Using these expressions it is possible to extract the values of all the noise model parameters directly from measurement. The proposed model is demonstrated by using noise data from both measurement and the noise simulation. Excellent agreement between simulated and measured noise data shows that the proposed model can be used for predicting the noise behavior of 40 nm MOSFET under different dimensions and operating conditions. The applicability of reported model for drain-current noise is also verified. As far as small-signal (i.e., linear) bias-dependent operation is concerned, it is shown how most of the findings of this work can also be used to predict the data of long channel devices in the strong-inversion regimes.

A directional HF noise model: Calibration and validation in the Australian region

The performance of systems using HF (high frequency) radio waves, such as over-the-horizon radars, is strongly dependent on the external noise environment. However, this environment has complex behavior and is known to vary with location, time, season, sunspot number, and radio frequency. It is also highly anisotropic, with the directional variation of noise being very important for the design and development of next generation over-the-horizon radar. By combining global maps of lightning occurrence, raytracing propagation, a model background ionosphere and ionospheric absorption, the behavior of noise at HF may be modeled. This article outlines the principles, techniques, and current progress of the model and calibrates it against a 5 year data set of background noise measurements. The calibrated model is then compared with data at a second site.

High-Frequency Noise Modeling of MOSFETs for Ultra Low-Voltage RF Applications

In this paper, analytical models for high-frequency drain-current noise, gate-current noise, and their cross-correlation of MOSFETs are presented with an emphasis on the weak- and moderate-inversion regions. Unified expressions offering excellent continuity and smoothness from weak- to moderate- and strong-inversion regimes were developed. It is demonstrated that the continuity and the accuracy of the calculated four noise parameters, such as minimum noise figure, normalized noise resistance, and optimum source conductance and susceptance, are significantly improved in the weak- and moderate-inversion regions by using the proposed unified noise model, which includes the junction-induced drain-current noise. A figure-of-merit is introduced to determine the optimum gate biasing point of MOSFETs, where high gain can be achieved at low driving power and low operating noise. The results obtained from the proposed model manifest good agreement with the on-wafer measurement results.

Substrate-Induced Noise Model and Parameter Extraction for High-Frequency Noise Modeling of Sub-Micron MOSFETs

In this paper, a substrate-induced drain-current noise model is developed in addition to the channel thermal noise to explain the non-white-noise characteristic found in the measured drain-current noise in the gigahertz range. The substrate-induced drain-current noise model is derived from the proposed small-signal equivalent circuit with a substrate coupling network and a substrate thermal noise source. The model parameter extraction method utilizing Y-parameter analysis on the proposed small-signal equivalent circuit is demonstrated. The model for the total drain-current noise, the gate-current noise, their cross-correlation, and thereafter the four noise parameters is presented and verified experimentally. Excellent agreement between simulated and measured noise data has been obtained over different dimensions and operating conditions.

Spectroscopy of canopy chemicals in humid tropical forests

Remote sensing of canopy chemistry could greatly advance the study and monitoring of functional processes and biological diversity in humid tropical forests. Imaging spectroscopy has contributed to canopy chemical remote sensing, but efforts to develop general, globally-applicable approaches have been limited by sparse and inconsistent field and laboratory data, and lacking analytical methods. We analyzed leaf hemispherical reflectance and transmittance spectra, along with a 21-chemical portfolio, taken from 6136 fully sunlit humid tropical forest canopies, and developed an up-scaling method using a combination of canopy radiative transfer, chemometric and high-frequency noise modeling. By integrating these steps, we found that the accuracy and precision of multi-chemical remote sensing of tropical forest canopies varies by leaf constituent and wavelength range. Under conditions of varying canopy structure and spectral noise, photosynthetic pigments, water, nitrogen, cellulose, lignin, phenols and leaf mass per area (LMA) are accurately estimated using visible-to-shortwave infrared spectroscopy (VSWIR; 400–2500 nm). Phosphorus and base cations are retrieved with lower yet significant accuracy. We also find that leaf chemical properties are estimated far more consistently, and with much higher precision and accuracy, using the VSWIR range rather than the more common and limited visible to near-infrared range (400–1050 nm; VNIR). While VNIR spectroscopy proved accurate for predicting foliar LMA, photosynthetic pigments and water, VSWIR spectra provided accurate estimates for three times the number of canopy traits. These global results proved to be independent of site conditions, taxonomic composition and phylogenetic history, and thus they should be broadly applicable to multi-chemical mapping of humid tropical forest canopies. The approach developed and tested here paves the way for studies of canopy chemical properties in humid tropical forests using the next generation of airborne and space-based high-fidelity imaging spectrometers.

Robustness of digitally modulated signal features against variation in HF noise model

High frequency (HF) band has both military and civilian uses. It can be used either as a primary or backup communication link. Automatic modulation classification (AMC) is of an utmost importance in this band for the purpose of communications monitoring; e.g., signal intelligence and spectrum management. A widely used method for AMC is based on pattern recognition (PR). Such a method has two main steps: feature extraction and classification. The first step is generally performed in the presence of channel noise. Recent studies show that HF noise could be modeled by Gaussian or bi-kappa distributions, depending on day-time. Therefore, it is anticipated that change in noise model will have impact on features extraction stage. In this article, we investigate the robustness of well known digitally modulated signal features against variation in HF noise. Specifically, we consider temporal time domain (TTD) features, higher order cumulants (HOC), and wavelet based features. In addition, we propose new features extracted from the constellation diagram and evaluate their robustness against the change in noise model. This study is targeting 2PSK, 4PSK, 8PSK, 16QAM, 32QAM, and 64QAM modulations, as they are commonly used in HF communications.

Analytical Modeling of High-Frequency Noise Including Temperature Effects in GaN HEMTs on High-Resistivity Si Substrates

In this paper, analytical modeling of high-frequency noise was carried out including temperature effects in AlGaN/GaN high electron mobility transistors (HEMTs) on high-resistivity Si substrates over a wide temperature range from -50°C to 200°C. The device's microwave S-parameters and overall noise parameters, including minimum noise figure (NFmin), equivalent noise resistance (Rn) , and optimum source reflection coefficient (|⌈opt| and ∠⌈opt) were measured over the whole temperature range. Its small signal equivalent circuit parameters (ECPs) and internal noise source coefficients (P, R, and C) were extracted at each measurement temperature and their temperature variances were fitted using a quadratic relationship. An analytical model of the overall noise parameters is proposed based on Pucel's PRC theory. It is compared with two other commonly used analytical models and verified with the measured data, including temperature dependence. The feedback capacitance Cgd was found to be important to accurately simulate all the measured noise parameters over temperature.

A new analytical high frequency noise parameter model for AlGaN/GaN HEMT

In this paper, we propose a simple analytical high frequency noise model for AlGaN/GaN HEMT including the effect of gate leakage current. Based on the DC and CV model proposed by our group recently, the expression for drain thermal noise current is derived using the impedance field method (IFM). Using the steady-state Nyquist theorem for multiterminal devices [1], the induced-gate noise is also calculated simply and explicitly. Also, from the comparison between various measured noise results and our simulation results, the validity of our model is clearly verified.

A Scalable RFCMOS Noise Model

This paper presents the high-frequency (HF) noise modeling of an RF MOSFET for a 90-nm technology node. A brief discussion on the noise measurement theory is presented to illustrate the limitation of the noise measurement system. The extracted noise sources were studied for their geometry and biasing dependences and by implementing additional noise sources into the small-signal RFCMOS model, accurate HF noise simulation for the transistor can be achieved. Verilog-A is used for the coding of the additional noise sources into the RFCMOS model and the added noise source will compensate the underestimation of the channel thermal noise from the BSIM3v3 core model. Simulated noise circles and the measured noise figures are plotted at other source impedances to show that all the noise parameters are simulated accurately. The biasing and geometry dependences of the measured and simulated noise parameters are presented to demonstrate the scalability of the developed HF noise model. The scalability feature in HF noise model can be implemented into the process design kit (PDK) so that more powerful PDK can be developed for the circuit designers to optimize and simulate their circuit design that requires stringent noise specifications. The accurate noise simulation can ensure better chance of success and reduce the number of tape-out and design cycle time.

High-frequency compact analytical noise model for double-gate metal-oxide-semiconductor field-effect transistor

Silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) are excellent candidates to become an alternative to conventional bulk technologies. The most promising SOI devices for the nanoscale range are based on multiple gate structures such as double-gate (DG) MOSFETs. These devices could be used for high-frequency applications due to the significant increase in the transition frequency fT for these devices. For low noise radiofrequency and microwave applications, high-frequency noise models are required. In this work, we present compact expressions to model the drain and gate current noise spectrum densities and their correlation for DG MOSFETs. These expressions depend on the mobile charge densities that are obtained using analytical expressions obtained from modeling the surface potential and the difference of potentials at the surface and at the center of the Si doped layer without the need to solve any transcendental equations. Using this model, the DG MOSFET noise performances are studied. The current and noise models can be easily introduced in circuit simulators.

High frequency noise modeling: Dependence on application

It is tempting to think that one could build a practical, general purpose noise model suitable for high or low frequencies and any application. For many signal processing and system applications this may be true, and one could incorporate directionality and spatial coherence. Recent developments in the use of wind-and sea-surface noise to determine geoacoustic properties by cross correlating hydrophone signals or beams demonstrate the need for more detail. The correlation peaks that correspond to absolute distances or ranges clearly require (frequency domain) coherence in any simulation. In contrast, layer information derived from angular reflection loss measurements by spectral factorization does not require coherence since it originates from an angular power spectrum. In both these cases the assumption of a uniform sheet of incoherent sources is adequate. However, to investigate the temporal statistics in either case, for instance to estimate averaging times, requires a fairly detailed model of the surface wave spatial field. Thus, the noise model is very much application dependent. These mechanisms and effects will be discussed in the context of experimental data.

MOSFET Modeling for RF IC Design

High-frequency (HF) modeling of MOSFETs for radio-frequency (RF) integrated circuit (IC) design is discussed. Modeling of the intrinsic device and the extrinsic components is discussed by accounting for important physical effects at both dc and HF. The concepts of equivalent circuits representing both intrinsic and extrinsic components in a MOSFET are analyzed to obtain a physics-based RF model. The procedures of the HF model parameter extraction are also developed. A subcircuit RF model based on the discussed approaches can be developed with good model accuracy. Further, noise modeling is discussed by analyzing the theoretical and experimental results in HF noise modeling. Analytical calculation of the noise sources has been discussed to understand the noise characteristics, including induced gate noise. The distortion behavior of MOSFET and modeling are also discussed. The fact that a MOSFET has much higher low-frequency limit is useful for designers and modelers to validate the distortion of a MOSFET model for RF application. An RF model could well predict the distortion behavior of MOSFETs if it can accurately describe both dc and ac small-signal characteristics with proper parameter extraction.

Small-signal and high-frequency noise modeling of SiGe HBTs

An improved and complete method for the small-signal and high-frequency noise modeling of SiGe HBTs in a BiCMOS process is presented. A comprehensive survey of the suggested parameter-extraction methodology for the SiGe HBT transistor model in conjunction with the analytically derived equations is given. The suggested transistor model is compatible with BiCMOS processes and takes into account the parasitic effects like the extrinsic capacitances and substrate effect. The accuracy of the proposed transistor model is verified by on-wafer S-parameter measurements up to 40 GHz. An important proof of the accuracy of the proposed parameter-extraction methodology is the presented physical noise model that can accurately predict the measured noise parameters up to our measurement frequency limit of 18 GHz. The noise model accuracy at various temperatures and biases is examined. Finally, the effect of the on-wafer contact pads on the noise performance of the transistor is investigated in detail.

Modeling of Degradation Effects on the High Frequency Noise of Metal–Oxide–Semiconductor Field-Effect Transistors

This paper proposes a hot-carrier stressed high-frequency noise model for metal–oxide–semiconductor field-effect transistors (MOSFETs). We first use the analytical method to develop a new fresh high-frequency noise model for MOSFETs, this model incorporates the effects of gate resistance, gate-induced current noise and non-local channel carrier heating, it can be used to calculate the minimum noise figure Fmin, optimized source admittance Yopt, and equivalent noise resistance Rn and admittance Gi. Secondly, we develop a new post-stress high-frequency noise model for MOSFETs, within this model the effects of hot-carrier stress induced interface states on the high-frequency noise performance can be evaluated. This model provides insightful device physics about the evolution of spatial noise sources within the channel versus stress time. The modeled results are in agreement with the experimental data of nMOSFETs with 0.25, 0.3 and 0.8-µm channel lengths.

The impact of the distributed RC effect on high frequency noise modeling of bipolar transistor

This paper describes the impact of the distributed RC effect in the intrinsic base region on the modeling of the output noise spectral density of a bipolar junction transistor. Simplified expressions to convert the distributed noise models to an improved hybrid-π model with the new equivalent noise sources are proposed. The accuracy of the new model has been verified by circuit simulations. Based on the new model, a noise analysis is done. The simulation results are compared with one by the conventional model. From this, the sensitivity of the noise parameters to the distributed RC effect is studied.

Bias dependence of high-frequency noise in heterojunction bipolar transistors

Hawkins' isothermal model developed to study noise in bipolar junction transistors (BJTs) is modified to investigate bias-dependent noise in heterojunction bipolar transistors (HBTs) by incorporating thermal effects. It is shown that the inclusion of thermal effects into the high-frequency noise model of HBTs is necessary as the temperature of the device may become very different from the ambient temperature, especially at high bias current. Calculation of the noise figure by including the thermal effect shows that the isothermal calculation may underestimate the noise figure at high bias current. It is observed that noise at low bias is ideality factor n dependent whereas high bias noise is insensitive to the variation of n. Moreover, the common base current gain plays a major role in the calculation of the minimum noise figure. The excellent fit obtained between the theoretical calculation and the measured data are attributed to the inclusion of the bias-dependent junction heating as well as C/sub De/ and C/sub bc/ into the present calculation.