Noise Equivalent Circuit Research Articles

External Partial Discharge Detection of Gas-Insulated Switchgears Using a Low-Noise and Enhanced-Sensitivity UHF Sensor Module

Ultra-high frequency (UHF) partial discharge (PD) detection is essential for routine maintenance of gas-insulated switchgear (GIS). Realizing low-noise detection with cost-effectiveness and ease of installation is promising but challenging. This paper presents a novel broadband noise-shaping network (BNSN) integrated with a printed monopole antenna (PMA) sensor to realize sufficient noise rejection and good impedance matching. Moreover, by analyzing the equivalent noise circuit and codesigning a high-speed preamplifier circuit with the proposed sensor, the detection sensitivity and anti-interference of the proposed sensor module are improved. The effectiveness and superiority of the proposed sensor are first verified in accordance with IEC 62478, followed by validations using a PD simulator and a real 24-kV GIS. The experimental results demonstrate that the proposed sensor module has the capability to identify different PD types even in noisy environments.

Optimal Design and Noise Analysis of High-Performance DBR-Integrated Lateral Germanium (Ge) Photodetectors for SWIR Applications

This work presents the high-performance Si/SiO2 distributed Bragg reflector (DBR)-integrated lateral germanium (Ge) p-i-n photodetectors (PDs) for atmospheric gas sensing and fiber-optic telecommunication networks in the short-wave infrared (SWIR) regime. In addition, this study also proposes an optoelectronic compact small-signal noise equivalent circuit model (SSNECM) of the designed device to compute the noise performance at the detectors’ output. Various figure-of merits including current under dark and illumination, responsivity, detectivity, bandwidth, and the noise of the proposed device are estimated at the room temperature (RT) for an incident optical power of 0.5 μW. Furthermore, the impact of width and height scaling on dark current, responsivity, and bandwidth are investigated to optimize the proposed device. The validation of the proposed model is done by comparing various parameters including dark current, responsivity, and detectivity of the designed device with other Ge PDs. The estimated results show the reduced trade-off between responsivity and bandwidth of the designed device. At λ=1550 nm, the proposed device achieves a high detectivity and SNR of >2×1011Jones and 120 dB (at 3 THz), respectively, with the bias voltage of -2V. These encouraging results pave the path for the future development of low-noise and high-speed detectors.

An improved transistor noise equivalent circuit model for silicon‐on‐insulator transistors considering the frequency dispersion effect

AbstractIn this paper, an improved transistor equivalent circuit noise model is proposed. This model takes the frequency dispersion effects into account and modified the induced gate current source (Ig) equation based on the classical Van der Ziel noise model. First, the conductance at Vd = 0 V (gd0) is derived from DC bias condition, and the accuracy of channel thermal noise (Id) is verified. Then, by analyzing the physical structure of the silicon‐on‐insulator (SOI) transistor, an equivalent lumped‐parameter circuit model is established. The element initial values are extracted based on the measured S‐parameters. Then, the parameters in the Ig equation are obtained through noise circle simulation in comparison with measurement data. In contrast to existing models, the frequency dispersion effect is analyzed and modeled using a three‐order polynomial. The results show that with respect to the traditional noise model, the noise circle's root‐mean‐square error of this work is decreased from 23.16 to 1.55.

Physics-Informed Neural Network for High Frequency Noise Performance in Quasi-Ballistic MOSFETs

A physics-informed neural network (PINN) model is presented to predict the nonlinear characteristics of high frequency (HF) noise performance in quasi-ballistic MOSFETs. The PINN model is formulated by combining the radial basis function-artificial neural networks (RBF-ANNs) with an improved noise equivalent circuit model, including all the noise sources. The RBF-ANNs are utilized to model the thermal channel noise, induced gate noise, correlation noise, as well as the shot noise, due to the gate and source-drain tunneling current through the potential barriers. By training a spatial distribution of the thermal channel noise and a Fano factor of the shot noise, underlying physical theories are naturally embedded into the PINN model as prior information. The PINN model shows good capability of predicting the noise performance at high frequencies.

Noise-Based Simulation Technique for Circuit-Variability Analysis

An accurate and efficient noise-based simulation technique for predicting the impact of device-parameter variability on the DC statistical behavior of integrated circuits is presented. The proposed method is validated on a source follower, a diode-load inverter and a current mirror based on organic thin-film transistors. Taking advantage of the standard noise analysis of a circuit, after translating the statistical variation of the electrical parameters of the transistors into equivalent-noise circuit components, the proposed technique yields results identical to those obtained from a Monte Carlo simulation, but in a significantly shorter amount of time.

Noise Characteristics of MgZnO-Based Metal–Semiconductor–Metal Photodetector

The noise characteristics of wurtzite MgZnO metal–semiconductor–metal photodetectors (PDs) are investigated by a proposed equivalent noise circuit model considering the effects of thermal noise and shot noise induced by the resistances and fluctuations of photogenerated carriers, respectively. Then, the impact of series and enhanced gain peaking techniques on the noise properties of the PDs is studied in detail. To verify the accuracy and effectiveness of this model, the computed noise power spectral density results are compared with the simulated data from Multisim. Results show that the output noise power is mainly determined by thermal noise when the PD works in a high-frequency region. These two gain peaking techniques, specifically, the enhanced gain peaking can decrease the shot noise power and the thermal noise power due to the leakage resistance by approximately 40 dBm/Hz, respectively, because of the introduction of gain peaking inductance and capacitance. At an applied bias of 1 V, the achieved noise equivalent power and the corresponding normalized detectivity of the thermal noise due to the parasitic resistance of the enhanced gain peaked circuit are approximately ${1.28} \times {10}^{-{7}}$ W and ${1.64} \times {10}^{{12}}$ Jones, respectively, with an incident light wavelength of 266 nm. This paper is valuable for developing high-speed MgZnO PDs.

Noise Limits in Thin-Film Magnetoelectric Sensors With Magnetic Frequency Conversion

To enable the measurement of low-frequency magnetic signals with cantilever type thin-film magnetoelectric sensors, magnetic frequency conversion transfers the frequency of the desired signal into the mechanical resonance of the cantilever. The system electronics for the realization of this approach and the approach itself introduce additional noise sources as compared with direct detection, which lowers the limit of detection. In this paper, the magnetic frequency conversion noise sources are reviewed, discussed, and evaluated for our setup. The model for the nonlinear transfer process is implemented in the time domain. This enables the consideration of the pump noise in a noise equivalent circuit. For the sensor type under investigation, the dominant noise near its optimal working point originates from the pump source. If the noise of the pump can be decreased and magnetic excess noise is not dominant, the noise limit is the thermal-mechanical noise of the sensor. The implementation of a filter after the excitation source decreases the limit of detection to 60 pT/ $\sqrt {\text {Hz}}$ at 10 Hz.

Investigation of gate induced noise in E‐mode GaN MOS‐HEMT and its effect on noise parameters

AbstractIn this paper, the effects of gate induced noise for a gate recessed enhancement‐mode GaN‐based metal‐oxide‐semiconductor high electron mobility transistor (MOS‐HEMT) is investigated. To analyze this, a surface potential–based compact model for gate induced noise is developed. The model is validated by comparing with TCAD device simulation results as well as with the available experimental data of GaN HEMT and MOS‐HEMT having different gate lengths and widths from the literature. With the help of the developed model, the effect of oxide thickness on different noise sources is investigated by considering all high‐frequency noise sources including the shot noise resulted from gate leakage current. The effects of gate leakage current on different technology dependent parameters such as oxide thickness and gate length are also investigated. A 2‐port noise equivalent circuit for GaN MOS‐HEMT is designed by considering all high‐frequency noise sources. The different noise parameter models are developed from the Y parameters of the 2‐port noise equivalent circuit and compared with available experimental data of GaN HEMT and MOS‐HEMT from literature. The impact of gate induced noise on all noise parameters is also investigated.

Noise of a JFET Charge Amplifier for Piezoelectric Sensors

A comprehensive noise model of a junction gate field-effect transistor (JFET) charge amplifier is presented for applications with piezoelectric sensors. Based on this previously reported amplifier structure, a noise equivalent circuit is derived and discussed. Universal noise gain expressions for each of the twelve considered noise sources are given. By means of an analytical description of the charge amplifier’s noise behavior, the design and optimization of such preamplifiers for various capacitive microelectromechanical sensor systems will be distinctly simplified. Calculations of the noise floor are compared with measurements with a cantilever-type magnetoelectric sensor and with the performance of a so far commonly utilized basic charge amplifier. With the JFET charge amplifier a noise reduction of approximately 22 dB is achieved in the vicinity of the utilized sensor’s resonance frequency of 7.45 kHz. The reported amplifier is the first which has no negative influence on the total noise level of a resonant magnetoelectric sensor system.

A new compact circuit-level model of semiconductor lasers: investigation of relative intensity noise and frequency noise spectra

We introduce a new compact noise equivalent circuit model of semiconductor lasers (SLs) from the rate equation including Langevin noise sources. The noise sources are described in terms of the spectral properties of the relative intensity noise (RIN) and frequency/phase noise (FN). Unlike the previous noise equivalent circuit models, which are based on two different DC and small-signal circuit models, using only a single circuit model, the static and dynamic responses and also the noise characteristics of SLs, can be investigated. We examine the validity of the presented noise circuit model by comparing the simulated results with the analytical and numerical results available in the literatures.

Thermal-Mechanical Noise in Resonant Thin-Film Magnetoelectric Sensors

Thin-film magnetoelectric sensors, i.e., composites of magnetostrictive and piezoelectric materials, are able to measure very low magnetic flux densities in the picotesla range. In order to further improve the limit of detection it is of high importance to understand and quantify the relevant noise sources. In this paper, a common model for the deflection noise in vibrational structures is applied to the cantilever structure of resonant magnetoelectric sensors. By means of deflection and noise measurements the existence of thermal-mechanical noise even in sensor structures with a size in the centimeter range is proven. Based on these findings a noise equivalent circuit is suggested which allows not only the distinction between the impact of different sensor-intrinsic noise sources and also the involvement of the preamplifier noise. We found that the thermal-mechanical noise is the dominant noise source if direct signal detection is performed at the first bending resonance frequency of the sensor. However, this kind of noise is not the limiting influence when applying magnetic frequency-conversion techniques.

Double stage low-frequency noise equivalent circuit of green InGaN LEDs for description of noise characteristics

To explain the current dependences of the mean-square value of low-frequency (LF) noise current in green InGaN light emitting diodes (LEDs), a double stage low-frequency noise equivalent circuit of the LED is proposed. It is shown that the nonmonotonic dependence of the LF noise on the injection current in the LED can be explained by the effect of two LF noise generators: a noise current generator, which is localized near the heterojunction and is determined by tunnel-recombination processes at the interface, and a generator determined by recombination processes in the active region of the structure.

Equivalent Noise Source: An Effective Method for Analyzing Common-Mode Noise in Isolated Power Converters

The interwinding capacitance of the transformer and the primary-side circuit nodes to ground capacitance are critical coupling path for common-mode (CM) noise in isolated power converters. In order to analyze the CM noise, the transformer interwinding capacitance is usually equivalent to lumped capacitance. In this paper, a generalized lumped capacitance model for constructing the CM noise equivalent circuit that is valid at low frequencies is derived. By simplifying the CM noise equivalent circuit based on Thevenin’s theorem, the equivalent noise source (ENS) for CM noise is proposed. The ENS is expressed by a linear combination of voltages in the converter, where the coefficients of these voltages are determined by transformer winding structure and the circuit configuration. With the help of ENS, the CM noise of the converter under different circuit configuration can be systematically analyzed and conveniently compared, which develops an effective reference for selecting a proper circuit configuration. Finally, the lumped capacitance model and the ENS for CM noise are verified by the experimental results.

Wave approach for noise modeling of gallium nitride high electron‐mobility transistors

AbstractThe wave approach has appeared as a very efficient tool for modeling as well as for measurements of noise parameters of microwave transistors. Having in mind the attractiveness of transistors in gallium nitride technology in modern communication systems, where it is very important to keep the noise on a low level and, thus, to have accurate transistor noise models, in this paper, the wave approach is applied for the noise modeling of high electron‐mobility transistor in gallium nitride technology. The noise wave representation of the transistor intrinsic circuit noise is used, where the noise wave parameters are modeled by exploiting the artificial neural networks. The modeling results, compared with the measured data and with those obtained by the conventional noise equivalent circuit model, provide a verification of the developed model accuracy. Copyright © 2015 John Wiley & Sons, Ltd.

Microwave noise modeling for MOSFETs

SummaryAnalytical expressions for the noise parameters of radio frequency metal oxide semiconductor field effect transistors (MOSFETs) are presented in this paper. These expressions are derived from an accurate small‐signal and noise equivalent circuit model, which takes into account the substrate parasitics and series inductances. Further, simplified expressions for noise parameters in the low‐frequency range are given. Good agreement is obtained between measured and calculated results up to 14 GHz for 0.35 µm MOSFET over a wide range of bias points. Copyright © 2015 John Wiley & Sons, Ltd.

GaN HEMT noise modeling based on 50‐Ω noise factor

ABSTRACTThe extraction of a high‐frequency ivalent circuit model plays a fundamental role for the development of any emerging transistor technology. Indeed, an equivalent circuit can provide a valuable support for microwave engineers to ensure a fast and reliable optimization of both device fabrication and circuit design. As far as gallium nitride (GaN) HEMTs are concerned, research efforts have been mostly focused on determining equivalent circuits able to reproduce their large‐signal behavior. Nevertheless, an increasing amount of interest is also being devoted to noise equivalent circuits, due to the interesting GaN technology noise performance. Within this context, the purpose of the present paper is to extract and fully validate an accurate noise model for GaN HEMTs based on a simple, fast, and reliable extraction procedure. The noise model is obtained by assigning an equivalent noise temperature to each resistor of the small‐signal equivalent circuit. The accuracy of the extracted noise model is confirmed by the good agreement between measured and simulated high‐frequency noise parameters. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:937–942, 2015

The noise equivalent circuit model of quantum-dot lasers

We derive the noise equivalent circuit model of semiconductor self-assembled quantum-dot (QD) lasers (SAQDL) from the rate equations including Langevin noise sources. This equivalent circuit allows a straightforward calculation of the noise of an SAQDL combined with electronic components. Using the presented model, we study how the carrier dynamics influences relative intensity noise (RIN) of QD lasers. We demonstrate that RIN is degraded with larger inhomogeneous broadening. Furthermore, we show that RIN is enhanced for lower quantum-dot coverage level.

Direct parameter-extraction method for MOSFET noise model from microwave noise figure measurement

A new method for the determination of the four noise parameters of the metal oxide semiconductor field effect transistors (MOSFETs) based on the noise figure measurement system without microwave tuner is presented. The noise parameters are determined based on a set of analytical expressions of noise parameters by fitting the measured noise figure of the active device. These expressions are derived from an accurate small signal and noise equivalent circuit model, which takes into account the substrate parasitics, pad capacitances, and series inductances. On-wafer experimental verification is presented and a comparison with tuner based method is given. Good agreement is obtained between simulated and measured results for 0.5 × 5 × 16 μm, 0.35 × 5 × 16 μm and 0.18 × 5 × 16 μm (gate length × number of gate fingers × unit gate width) MOSFETs.

Analysis of noise properties of an optocoupler device

AbstractIn the paper, localization of a source of random telegraph signal noise (RTS noise) in optocoupler devices of CNY 17 type was defined. The equivalent noise circuit in low frequency noise for these types of optocouplers was proposed.

Effect of FN stress and gate-oxide breakdown on high-frequency noise characteristics in deep-submicrometer nMOSFETs

The impact of Fowler-Nordheim (FN) stress and oxide breakdown on high-frequency noise characteristics in 0.18 μm nMOSFET has studied. Noise characteristics of the devices at different leakage levels and breakdown hardness are compared. The results have shown a strong dependence of degradation of noise parameter on the gate leakage. The degradation mechanisms are analyzed by extraction of the channel and gate noise using a noise equivalent circuit model. It has been found that gate shot noise, which is commonly ignored in the as-processed nMOSFET, plays a dominant role in determining the high frequency noise in the post-oxide breakdown nMOSFET. The effect of FN stress and oxide breakdown is negligible.