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OBJECTIVE: Diffuse correlation spectroscopy (DCS) is an optical technique that allows for the non-invasive measurement of blood flow. Recent work has shown that utilizing longer wavelengths beyond the traditional NIR range provides a significant improvement to signal-to-noise ratio (SNR). However, current detectors both sensitive to longer wavelengths and suitable for clinical applications (InGaAs/InP SPADs) suffer from suboptimal afterpulsing and dark noise characteristics. To overcome these barriers, we introduce a cross correlation method to more accurately recover blood flow information using InGaAs/InP SPADs. METHODS: Two InGaAs/InP SPAD detectors were used for during in vitro and in vivo DCS measurements. Cross correlation of the photon streams from each detector was performed to calculate the correlation function. Detector operating parameters were varied to determine parameters which maximized measurement SNR. State-space modeling was performed to determine the detector characteristics at each operating point. RESULTS: Evaluation of detector characteristics was performed across the range of operating conditions. Modeling the effects of the detector noise on the correlation function provided a method to correct the distortion of the correlation curve, yielding accurate recovery of flow information as confirmed by a reference detector. CONCLUSION: Through a combination of cross-correlation of the signals from two detectors, model-based characterization of detector response, and optimization of detector operating parameters, the method allows for the accurate estimation of the true blood flow index. Significance: This work presents a method by which DCS can be performed at longer NIR wavelengths with existing detector technology, taking advantage of the increased SNR.

A 320 x 240 indirect time-of-flight (i-ToF) image sensor with a 5.6-μm two-tap 1.5-V pump gate modulation pixel has been designed. Novel characteristics, such as the optimized pinned layer doping and potential buffer region (PBR) structure with pump gate modulator (PGM), are proposed to achieve a maximum lateral modulation electric field of 1500 V/cm under the front-side illumination (FSI) process. As a result, the proposed time-of-flight (ToF) sensor shows 200-mW power consumption and 54% demodulation contrast (DC) at 50-MHz modulation frequency, depth noise less than 1% with 940-nm illuminator from 0.3 to 3 m.

In this paper, the design considerations and basic equations related to thick-film screen-printed sensing devices are included. The geometry of the device and the patterns of the functional sensing film, or of the electrodes are taken into account for the determination of the operational frequency, noise voltage, quality factor and other key parameters, related to the proper work of the resistive, capacitive and surface acoustic wave based sensors. The determination of some parasitic components and possible errors is also provided. The focus is put on the most widely spread coating patterns related to this technology – meander and comb-shaped. The technology flow chart of the screen-printing technology is given and the approaches for fine-tuning the resistance at the thick-film resistive sensors are discussed. Comparison of the typically used materials for substrates, resistive, conductive, and dielectric coatings is made. Criteria for the selection of the different pastes or inks for specific applications are mentioned.

Magnetic sensors based on tunneling magnetoresistance (TMR) effect exhibit high sensitivity, small size, and low power consumption. They have gained a lot of attention and have potential applications in various domains. This study first introduces the development history and basic principles of TMR sensors. Then, a comprehensive description of TMR sensors linearization and Wheatstone bridge configuration is presented. Two key performance parameters, the field sensitivity and noise mechanisms, are considered. Finally, the emerging applications of TMR sensors are discussed.

The multi-mode noise is an important issue for the optoelectronic oscillator (OEO) in generating a spectrally pure microwave. Especially in oscillators with low phase noise, increasing the cavity length to improve the phase noise performance will make the mode interval smaller, which is more likely to cause multi-mode noise. Here, we proposed a low phase noise and high side-mode suppression ratio self-injection-locked OEO based on frequency conversion filtering. We theoretically and experimentally studied the influence of the phase noise of the external microwave source on the proposed OEO and, as a comparison, the conventional injection-locked OEO. The results show that, compared with the traditional injection-locked OEO, the proposed OEO is less sensitive to the phase noise of the external microwave source. Under the same experimental conditions, the proposed OEO achieved the same side-mode suppression ratio and the phase noise is reduced by 30 dB at 10 kHz offset from the 10-GHz carrier compared with the conventional injection-locked OEO.

Back-illuminated charged-coupled device (BI-CCD) arrays increase quantum efficiency but also amplify etaloning, a multiplicative, wavelength-dependent fixed-pattern effect. When spectral data from hundreds of BI-CCD rows are combined, the averaged spectrum will generally appear etalon-free. This can mask substantial etaloning at the row level, even if the BI-CCD has been treated to suppress the effect. This paper compares two methods of etalon correction, one with simple averaging and one with row-by-row calibration using a fluorescence standard. Two BI-CCD arrays, both roughened by the supplier to reduce etaloning, were used to acquire Raman spectra of murine bone specimens. For one array, etaloning was the dominant source of noise under the exposure conditions chosen, even for the averaged spectrum across all rows; near-infrared-excited Raman peaks were noticeably affected. In this case, row-by-row calibration improved the spectral quality of the average spectrum. The other CCD’s performance was shot-noise limited and therefore received no benefit from the extra calibration. The different results highlight the importance of checking for and correcting row-level fixed pattern when measuring weak Raman signals in the presence of a large fluorescence background.

This paper describes the design, fabrication, and record performance of a new class of ultra-wideband wavelength tuning, ultra-low noise semiconductor laser, the Integrated Coherent Tunable Laser (ICTL). The ICTL device is designed for, and fabricated in, a CMOS foundry based Silicon Photonics platform, utilizing heterogeneous integration of III-V material to create the integrated gain section of the laser - enabling high-volume mass-market manufacturing at low cost and with high reliability. The ICTL incorporates three or more ultra-low loss micro-ring resonators, with large ring size, in a Sagnac loop reflector geometry, creating exceptional laser reflector performance, plus an extended laser cavity length that enables highly-coherent output; ultra-low linewidth and phase noise. This paper describes record integrated laser performance; 118 nm wavelength tuning, covering S-, C- and L-bands, with Lorentzian linewidth

This paper reports a high-performance, low-power temperature sensor suitable for wireless IoT devices/RFID tags. The system utilizes a mostly digital approach to achieve energy-efficient, sub-μW operation with a resistor-based temperature sensor. A sampled, incomplete-settling, switched-capacitor-based Wheatstone bridge is read out using a digital frequency-locked loop (DFLL) while harnessing the quasi-periodic limit cycles to reduce in-band noise. Implemented in a 65 nm CMOS process, it consumes 310 nW and achieves 9.8 mK resolution in a 10 ms conversion time. This results in a 297 fJ∙K2 figure-of-merit (FoM) and low energy (3.1 nJ/meas.).

This brief presents a class-C voltage-controlled oscillator (VCO) that ensures a robust start-up with low phase noise and high power efficiency. The proposed start-up scheme, which uses a voltage converter that operates according to the output state, relieves the start-up difficulty by supplying a timevarying bias voltage to the core transistors and allows the VCO to operate in an optimal state. The start-up circuitry is enabled only during initial operation, so power efficiency is improved without phase noise degradation. Furthermore, a capacitor array with a high quality factor is implemented by a direct capacitor connection that exhibits low series resistance. Fabricated with a 65-nm CMOS, the VCO demonstrates a frequency tuning range of 13.1% from 19.3 to 22.0 GHz. The measured minimum phase noise at a 1-MHz offset is --106.33 dBc/Hz at an oscillation frequency of 19.7 GHz, while dissipating 3.8-mW of power from a 1.0-V supply. The VCO occupies an active area of 0.064 mm2. It reveals a figureof-merit and figure-of-merit with area of --186.4 and --198.3 dBc/Hz, respectively.

In magnetic nanoparticle tomography (MNT), the reduction of artefacts and the calculation time can be used to estimate the position of magnetic nanoparticles (MNPs). Non-negative least squares (NNLS) inverse problem analysis has been used in MNT systems for this task. However, owing to the presence of measurement noise and the high sensitivity of the NNLS method, it often estimates certain MNPs inaccurately, i.e., it generates artefacts. In addition, its calculation time is very high. In this study, we applied the minimum variance spatial filter (MV-SF) inverse problem analysis to MNT and estimated the position of an MNP sample containing 100 μ g of Fe. Using the MV-SF method, MNP samples placed at a depth of 25–40 mm were observed to have no artefacts. Moreover, the MV-SF method was also observed to be faster than the NNLS method by a factor of approximately 20. These results verify the feasibility of the MV-SF method for estimating the MNP positions in an MNT system.

Lateral III-V nanowire (NW) MOSFETs are a promising candidate for high-frequency electronics. However, their circuit performance is not yet assessed. Here, we integrate lateral nanowires (LNWs) in a circuit environment and characterize the transistors and amplifiers. MOSFETs are fabricated in a simple scheme with a dc transconductance of up to 1.3 mS/μm, ON-resistance down to 265 Ω · μ m, and cutoff frequencies up to 250 GHz, measured on the circuit level. The circuit model estimates 25% device parasitic capacitance increase due to back-end-of-line (BEOL) dielectric cladding. A low-noise amplifier input stage is designed with optimum network design for a noise matched input and an inductive peaking output. The input stage shows up to 4-dB gain and 2.5-dB noise figure (NF), at 60 GHz. Utilizing gate-length scaling in the circuit environment, the obtained normalized intrinsic gate capacitance value of 0.34-aF/nm gate length, per NW, corresponds well to the predicted theoretical value, demonstrating the circuit's ability to provide intrinsic device parameters. This is the first mm-wave validation of noise models for III-V LNW MOSFETs. The results demonstrate the potential for utilization of the technology platform for low-noise applications.

In this paper, we present an improved multi-order parameter model for multi-component model of polycrystalline solidification. We introduce an interpolation function in the phase field dynamical equation to obtain controllable grain boundary energy at large undercooling. The same interpolation function is also employed in the kinetics coefficient to allow for better control of grain boundary migration. Temperature dependent phase field parameters and noise terms are consistently coupled into the dynamics of a binary system in a manner that allows for quantitative simulations in the thin interface limit. The model is applied to multi-phase solidification in Al-Cu alloy, where a parabolic fitting method is employed to model the free energy of Al-Cu phases and two-phase nucleation is demonstrated in directional solidification.

In this work, the low-frequency noise (LFN) characteristics of hafnium-zirconium oxide (HZO) ferroelectric field-effect transistors (FeFETs) with and without high-pressure forming gas annealing (HPA) treatment are investigated. The origin of 1/f noise in the FeFET without HPA is changed from carrier number fluctuation to Hooge’s mobility fluctuation after wake-up due to the remote phonon scattering from the polarized HZO. Also, Hooge’s parameter is increased by the program/erase (P/E) cycling-induced stress. On the contrary, only the correlated mobility fluctuation is increased after the wake-up in the FeFET with HPA. Furthermore, the LFN of the FeFET with HPA shows robustness to P/E cycling-induced stress after the wake-up, showing superb endurance performance.

Magnetic field shields are important for electronic equipment, ultrahigh-sensitivity sensors, and electrical instruments. For ultrahigh-sensitivity atomic sensors, in particular, ferrite shields with low intrinsic magnetic noise are widely used. In this article, the calculation methods of longitudinal and transverse magnetic noise, which are calculated by loss, are analyzed. The experimental results confirm the feasibility of the model. Using the loss separation method, it is proved that the loss of ferrite magnetic shielding is mainly hysteresis loss, which is below 100 Hz. To effectively reduce the magnetic noise, we analyze the effect of structure parameters on the longitudinal and transverse magnetic noise, and the optimized parameters are obtained. The results show that the longitudinal magnetic noise decreases with the increasing aspect ratio and stabilize eventually. When the aspect ratio exceeds 1, the transverse magnetic noise remains practically unchanged. When the external diameter is fixed, by optimizing the thickness of the magnetic shield, the optimal solution for the longitudinal and transverse magnetic noise is obtained.

A novel VCSEL array for high-efficiency, high-speed, and high-brightness performance is demonstrated. In contrast to the traditional VCSEL arrays, which have several independent VCSEL cavities in parallel, the novel array structure has additional passive optical waveguides connecting each cavity. In addition, Zn-diffusion and oxide-relief structures are adopted for each single element of the array to obtain the high-brightness (single-mode; SM) output and relax the RC-limited bandwidth. Comparison is made to the traditional reference array. Although the values of the oxide-relief apertures are close to each other, the novel demonstrated arrays exhibit a higher wall plug efficiency, larger maximum output power, and better eye-opening for high-speed data transmission, when both of their output optical spectra are quasi-(SM) with close narrow divergence angle values (FWHM: ∼6°). The superior performance of the demonstrated array for (quasi-) SM operation can be attributed to the dilution of the photon density in the SM output pattern from each VCSEL unit through the connections of passive waveguide. Furthermore, it also enhances the coherence between the neighboring VCSEL emitters, minimizing their interference noise which occurs under large signal modulation. This novel 940 nm VCSEL array has good potential to serve as a light source in free-space optical communication.

VO2(B) is a metastable phase of VO2 composed of both edge-sharing and corner sharing irregular VO6 octahedrons. VO2(B) is a metallic phase at room temperature, and shows large tunnels in the lattices that allows rapid intercalation and deintercalation of metal ions. It also shows high temperature coefficient of resistance (TCR) and low 1/f noise with appropriate resistance. These merits attract much attention in the field of metal ion battery and uncooled infrared detectors. Here we will give a systematically review on the advances in development of preparation and applications of VO2(B). We focus on the structure and properties of VO2(B) that strongly affects the application in metal ion battery and uncooled infrared detectors, and the way of control them in different preparation methods. New application in gas and humidity sensing is also mentioned. At the end, we briefly discuss the possible directions of VO2(B) materials in the future's research, hoping that this article can provide a valuable reference for research of VO2(B) in the future.

We report Al0.3InAsSb/Al0.7InAsSb digital alloy n-barrier-n (nBn) photodetectors that operate in the 2-μm wavelength window. The AlxIn1-xAsySb1-y digital alloy material system exhibits near-zero valence-band offset, which is beneficial for nBn photodetectors. At 300 K these Al0.3InAsSb/Al0.7InAsSb nBn photodetectors have achieved specific detectivities of 1.7 × 10 10 and 3.0 × 10 10 Jones under 2-μm and 1.8-μm illumination, respectively. The dark current density at -0.5 V bias decreases from 3.1 × 10 -3 A/cm 2 at 300 K to 1.6 × 10 -10 A/cm 2 at 120 K, where the dominant dark current component is tunneling. The area-dependence of key performance parameters show that for mesa diameter ≤ 250 μm, surface defects assume a dominant role in the total noise.

It is critical for maintaining the safe operation of turbine blades to inspect the potential structural damages promptly. However, the industry still lacks efficient tools for inspection of the curved surface. In this respect, in this article, a new flexible probe with in-plane differential coils is proposed. With the sophisticated configuration, the probe has four channels, which complement each other in terms of sensitivity to defects of different orientations. The in-plane differential scheme nulls the background signal and reduces the noise resulting in high sensitivity to microdefects. The probe can be bent according to the curved surface due to its flexible configuration. A three-dimensional finite-element method model based on the cluster parallel computation is utilized to study the feasibility and performance of the probe, and a prototype probe is developed and tested by scanning defects on the curved surface of a turbine blade sample. Furthermore, a data fusion method is proposed to obtain a better signal-to-noise ratio so that defects with length*width*depth = 2.5 mm*0.1 mm*0.1 mm can be identified. Based on repeated experiments, it is observed that the probability of detection with the fusion of the multichannels is higher than that of every single channel demonstrating that the data fusion increases the reliability of the inspection.

In this letter, a V-band (50-75 GHz) ultralow-power low-noise amplifier (LNA) in 90-nm CMOS technology is presented. A double-transformer-coupling (DTC) technique is used to improve the gain and noise performance of the LNA. The combination of self-resonant-transformer-matching (SRTM) and gain-boosting technique is also utilized to achieve wideband output matching with high gain in a single-ended common-source (CS) amplifier. The measured small-signal gain is 16.8 dB with 3-dB bandwidth that covers from 50 to 67 GHz and the measured lowest in-band noise figure (NF) of 5.4 dB. The LNA consumes only 5.7 mW with a compact chip area of 0.6 x 1 mm².

Accurate localization of single particles plays an increasingly important role in a range of biological techniques, including single molecule tracking and localization-based superresolution microscopy. Such techniques require fast and accurate particle localization algorithms as well as nanometer-scale stability of the microscope. Here, we present a universal method for three-dimensional localization of single labeled and unlabeled particles based on local gradient calculation of microscopy images. The method outperforms current techniques in high noise conditions, and it is capable of nanometer accuracy localization of nano- and micro-particles with sub-ms calculation time. By localizing a fixed particle as fiducial mark and running a feedback loop, we demonstrate its applicability for active drift correction in sensitive nanomechanical measurements such as optical trapping and superresolution imaging. A multiplatform open software package comprising a set of tools for local gradient calculation in brightfield and fluorescence microscopy is shared to the scientific community.

Voltage imaging in cells requires high-speed recording of small fluorescent signals, often leading to low signal/noise ratios. Because voltage indicators are membrane bound, their orientations are partially constrained by the plane of the membrane. We explored whether tuning the linear polarization of excitation light could enhance voltage indicator fluorescence. We tested a panel of dye- and protein-based voltage indicators in mammalian cells. The dye BeRST1 showed a 73% increase in brightness between the least and most favorable polarizations. The protein-based reporter ASAP1 showed a 22% increase in brightness, and QuasAr3 showed a 14% increase in brightness. In very thin neurites expressing QuasAr3, improvements were anomalously large, with a 170% increase in brightness between polarization parallel versus perpendicular to the dendrite. Signal/noise ratios of optically recorded action potentials were increased by up to 50% in neurites expressing QuasAr3. These results demonstrate that polarization control can be a facile means to enhance signals from fluorescent voltage indicators, particularly in thin neurites or in high-background environments.

Three-level (3L) inverters suffer from higher parasitic inductance due to the increased number of series-connected switches in a single current commutation loop (CCL) results in a larger size of CCL compared to their two-level (2L) counterparts. As such, semiconductors are subjected to higher voltage stress and severe ringing at the switching transient. While silicon carbide's (SiC) faster switching speed improves overall efficiency by reducing switching loss, the faster voltage, and current gradient (d v /d t and d i /d t ) generate electromagnetic interference (EMI) noise, requiring a larger and complicated filter stage design. To solve this problem, an optimized 3L T-type neutral point clamped power module has been proposed with a hybrid combination of the switch (SiC mosfet + Si IGBT) rated for 1200 V/160 A. Two direct bonded copper (DBC) substrates have been stacked to have a vertical power loop using laser-drilled vias, which provides low commutation loop inductance as low as 4.6 nH for the major CCLs including the wire bond. Other associated CCLs have also been identified and optimized. Additional DBC in the package will be acting as an EMI shield. The EMI noise has been compared to a traditional power module and a 21 dB reduction of common-mode noise has been observed.

This article presents a frontend amplifier based on the 50-μm channel length n-type only indium-tin-oxide (ITO)-stabilized ZnO thin-film transistors (TFTs) on glass substrate. The amplifier has an external-bias ac-coupled, open-loop capacitor bootstrap structure. The area and power consumption are 41 mm² and 0.1 mW (8-V supply), respectively. Electrical measurement results show a gain of 20 dB, a bandwidth of 3 Hz-6 kHz, a common-mode rejection ratio (CMRR) up to 42 dB, an input impedance of 100 MΩ , and an input-referred noise of 106 μV $_{rms}$ (integrated from 1 to 200 Hz). The noise efficiency factor (NEF) and power efficiency factor (PEF) of the amplifier are, respectively, 248 and 4.9 x 10⁵, which is comparable among the state of the arts. The amplifier is successfully used to measure the heart-rate signal, which demonstrates its practicality.

Stress-induced damage in a MOSFET can be cured by Joule heating, which can be produced by an intentional forward junction current ( ${I}_{\textbf {FWD}}$ ). This curing effect can be further enhanced by the simultaneous application of gate biasing, which does not influence the ${I}_{\textbf {FWD}}$ . A MOSFET was intentionally degraded by harsh hot-carrier injection (HCI) then the damage was cured and nearly returned to its pristine state. The improved self-curing effect was quantitatively verified using low-frequency noise (LFN) analyses. Self-curing by internal heat from the ${I}_{\textbf {FWD}}$ more effectively cured the HCI damage than a nonself-curing using external heat from a hot chuck.

A micro Coriolis flow sensor accurately measures small mass flows without being affected by properties of the fluid. This paper presents a micro Coriolis mass flow sensor driven by PZT thin film piezoelectric actuators, which allows a combination of large actuation force, low power dissipation and virtually no self-heating. The sensor was fabricated using surface channel technology, resulting in a tube diameter of 40,μm and a thin silicon-rich silicon nitride tube wall of 1.2,μm thick, with a few additional steps to form the integrated piezoelectric actuators. The integrated actuators can actuate the sensor into both swing mode and twist mode. Both actuation modes were evaluated for different fluids and the results are presented in this paper. In the case of swing mode actuation, an optical readout was used to detect the resulting Coriolis movement, resulting in a relatively low sensitivity. In the case of twist mode actuation, a capacitive readout was used and, in comparison to previously published devices, a high mass flow sensitivity was achieved thanks to an optimized readout design. The measurement results show the read-out noise has a standard deviation of 0.15% of the full scale of 1.8 gh⁻¹ when actuated in the twist mode. [2020-0392]

Electric utilities are looking for novel methods to increase the transmission capacity of existing transmission lines. The conversion of conventional AC towers to hybrid AC/DC lines allows for significantly more power and reduces the need for new rights of way. Still, due to the fixed geometry, there will be coupling effects between the AC and DC systems. Corona effects, such as audible noise, which are crucial for public acceptance, will change consequentially. An outdoor test setup is used to investigate the corona audible noise and partial discharges of parallel AC and DC bundles. The effect of a DC bias on the AC corona as well as an AC ripple on DC corona are studied for varying surface gradients and weather conditions. The AC and DC audible noise clearly increased for most cases of a DC bias or AC ripple, respectively. The relative increase was found higher if the conductor was only slightly above corona as it happens in dry conditions with light pollution. Still, the highest level of AC audible noise was observed during wet weather and for DC during dry conditions.

Small-angle X-ray scattering (SAXS) coupled with computed tomography (CT), denoted SAXS-CT, enables the spatial distribution of the characteristic parameters of nanoscale structures inside samples to be visualized. In this work, a new scheme with Tikhonov regularization was developed to remove the effects of artifacts caused by streak scattering originating from contour regions of the sample., Small-angle X-ray scattering (SAXS) coupled with computed tomography (CT), denoted SAXS-CT, has enabled the spatial distribution of the characteristic parameters (e.g. size, shape, surface, length) of nanoscale structures inside samples to be visualized. In this work, a new scheme with Tikhonov regularization was developed to remove the effects of artifacts caused by streak scattering originating from the reflection of the incident beam in the contour regions of the sample. The noise due to streak scattering was successfully removed from the sinogram image and hence the CT image could be reconstructed free from artifacts in the contour regions.

Solution-processable all-inorganic lead halide perovskites are under intensive attention due to their potential applications in low-cost high-performance optoelectronic devices such as photodetectors. However, solution processing usually generates structural and chemical defects which are detrimental to the photodetection performance of photodetectors. Here, a polymer additive of polyethylene glycol (PEG) was employed to passivate the localized defects in CsPbI2Br films through the Lewis acid-base interaction. The interfacial defects were passivated efficiently by introducing a trace amount of a PEG additive with a concentration of 0.4 mg mL-1 into the CsPbI2Br precursor solution, as suggested by the significantly reduced trap density of state, which was revealed using thermal admittance spectroscopy. Fourier transform infrared spectrum characterization showed that rather than Cs+ or I-, a Lewis acid-base interaction was established between Pb2+ and PEG to passivate the defects in the CsPbI2Br perovskite, which leads to large suppression of noise current. Both specific detectivity and linear dynamic range improved from 4.1 × 109 Jones and 73 dB to 2.2 × 1011 Jones and 116 dB, respectively. Our work demonstrates the feasibility of employing an environmentally stable polymeric additive PEG to passivate defects for high photodetection performance in all-inorganic perovskite photodetectors.

A differential quench and reset (QR) configuration for single-photon avalanche diodes (SPADs) is proposed and investigated in this work. Compared to the traditional single QR configuration in which only one QR circuit is connected to either the cathode or anode of the SPAD, the differential QR configuration consists of two QR circuits to quench and reset through both the cathode and anode terminals. Using a SPAD fabricated in a 65 nm CMOS process, the measurement results of the traditional single passive quench and reset (SPQR) circuit and the proposed differential passive quench and reset (DPQR) circuit shows that the SPAD with the DPQR circuit presented a reduced reset time, an improved timing performance, an increased count rate and a decreased afterpulsing. In addition, the differential output pair from the DPQR circuit has the potential to increase the signal-to-noise ratio of the detection system due to its ability to reject common-mode noise and interference.

There is a constant need for Hall-effect magnetic sensors with lower noise and lower offset for the high accuracy analog applications driven primarily by industrial and automotive markets, for example, high dynamic range current sensing for battery management in electric vehicles. Graphene-based Hall sensors (GHSs) demonstrate low thermal noise due to their high carrier mobility but suffer from large low-frequency flicker noise and offset limiting the prevalent low-frequency applications. In this paper, we present the results of a recently proposed gate modulation scheme for GHSs that uses dynamic ambipolar operation to up-convert the input magnetic signal to higher modulating frequencies while the offset and flicker noise remain spectrally unchanged and thus enabling thermal noise limited performance. We implement a prototype GHS using a scalable fabrication process with CVD graphene transferred on to silicon-oxide and followed by standard thin film and subsequent photolithographic processes. The measurement results confirm the effectiveness of dynamic ambipolar gate modulation technique in producing low offset of $- 524\,\,\mu \mathrm{T}$ in conjunction with three orders of magnitude estimated improvement in the low frequency noise performance.

To accommodate special applications where installation space is limited and noise and vibration requirements are high, a new triple screw pump structure was proposed, which was integrated into a servo motor. The design optimizes the profile of the master and slave screws of the embedded triple screw pump. The temperature and pressure fields of the embedded triple screw pump, as well as the heat transfer and pressure distribution between the fluid in the pump and the screw, were investigated through a thermal-fluid-structure approach. The deformation and stresses of the screw were compared for three operating conditions: temperature loading, pressure loading, and thermal-fluid-structure coupling. The results show that the deformation and stresses in the screw tended to increase with increasing pressure and temperature and the pressure load caused more significant deformation and stresses in the screw than the temperature load. The screw deformation caused by pressure loading was found to be the main factor affecting the thermal-fluid-structure coupling. The screw deformation after coupling was smaller than the sum of the screw deformation caused by individual temperature and pressure loads, and the stress values were the same. The results indicate that the coupling action weakens the deformation and stresses in the master and slave screws.

Advances in microelectronics have enabled smaller technical nodes, lower threshold voltages, and greater working frequencies. Even though VLSI circuit performance and power consumption have improved as a result, the reliability of the designs has suffered. A fall in noise resistance and an increase in uncertainty from multiple sources of variability make circuits more vulnerable as technology scales down. Fault tolerant techniques are commonly used in safety-critical applications. Three-dimensional electrical devices like double gate, tri-gate, and nanowire field-effect transistors (FETs) give an alternative approach since they regulate the device channel better electrostatically. In this paper, a new form of FinFET with asymmetric gate and source/drain connections is developed, and its simulation results are shown. Asymmetric FinFETs exhibit better short-channel behavior when the current density is increased, according to the results of the benchmarking. High aspect ratio FinFETs give greater current per area while demanding significantly fewer horizontal geometry constraints, making them ideal for situations where conventional scaling has hit its physical limits. The suggested multigate FinFET provides improved performance in low-power and high-frequency applications, according to the experimental results. The work report also includes an evaluation of the proposed multigate FinFET’s dependability.

The false apparent temperature change caused by moving objects generates noise components in thermoelastic stress analysis (TSA) and rapid fatigue limit estimation based on energy dissipation. This paper proposes a motion compensation system using visible-infrared synchronous measurements to remove apparent temperature changes. A new dissipative energy evaluation method that combines visible and infrared measurements is proposed. The displacement information is obtained using digital image correlation (DIC) in visible images. Visible and infrared measurements are performed on the same surface simultaneously. The displacement information obtained from the visible image is reflected in the infrared image by applying image processing for spatial synchronization. A white speckle pattern required for DIC is applied to black paint, and this white paint does not affect the infrared measurement. In the new method, the time series of strain obtained from the visible image is used to calculate the thermoelastic temperature change, which is then compared with the actual temperature change obtained via infrared thermography to evaluate the temperature change due to energy dissipation. Motion compensation systems have been applied to TSA and dissipative energy measurements. It is confirmed that the edge effect and false apparent dissipated energy can be removed using the developed system. It is discovered that the energy dissipation behavior within one cycle of the load, which cannot be evaluated via conventional frequency analysis, can be observed comprehensively. This synchronous measurement system is useful for enhancing the accuracy of TSA and dissipated energy measurement.

Force measurement plays an important role in assessing the status of electromechanical system and the performance control. Force sensors are the most common devices that used for measuring force, and are made with various materials and fabrication methods. However, the components of most sensors are in contact with each other, which bring a lot of inconvenience to design and preparation the sensor, and also cause the interference and noise transmission between the substrate and conversion element. In this paper, a new force measurement method based on the auxetic structure is proposed. The scheme of this method consists of three parts, which are light source, auxetic structure and the solar cell. The auxetic structure can be regarded as a substrate and solar cell as a conversion element. These three parts are not in contact with each other. The basic principle of the proposed method is that the change of transmittance of the auxetic structure due to elastic deformation is transformed into the change of output current of the solar cell. The effectiveness of the proposed method is investigated by geometrical analysis and experiment. The sensitivity and linearity error of the proposed method based on the auxetic structure are 0.04mV/N and 8.17% respectively, while that based on the non-auxetic structure are 0.02mV/N and 14.78%. The results prove the feasibility of the proposed method and this study provides new structural insights for force sensors and presents future research directions.

GaAs-based p-i-n 850 nm infrared photodetectors with a narrow bandpass characteristic were successfully fabricated and demonstrated by epitaxial growth technology. The photo to dark current ratios of the fabricated PDs were $1.76\times10$ 7 and $2.08\times10$ 3 at 0 and −5 V, respectively. It can be seen clearly that our fabricated PDs can achieve a very steeply and rapidly falling cut-off bandpass characteristic by inserting a p-Al0.1Ga0.9As filter layer. The full width at half maximum of the photo response was only 65.9 nm. Then, the peak responsivity value of the fabricated PDs occurred at 855 nm was 0.49 A/W with a quantum efficiency of 71.2% at −1 V. Moreover, the low frequency noise of the fabricated PDs was dominated by 1/f-type noise. And, the best detectivity was calculated to be $1.17\times10$ 13 cmHz0.5W−1 at a bias voltage of 0 V.

Purpose The effects of tube potential selection with a Computed Tomography (CT) Automatic Tube Current Modulation (ATCM) system on radiation dose and image quality have been investigated on a Canon CT scanner. The use of different values of tube voltage for imaging and the appropriate settings of the ATCM system were evaluated. Methods The custom made phantom consisted of three sections of different size with inserts of various materials. It was scanned using tube potentials of 80-140 kV and different image quality ATCM settings. CTDIvol and image quality in terms of noise, contrast, and contrast to noise ratio (CNR) for air, Polyethylene (PE), Acrylic, Polyoxymethylene (POM) and Polyvinylchloride (PVC) were analysed. A figure of merit (FOM) was estimated by combining CNR and CTDIvol. Results CTDIvol values were similar for all values of tube voltage and individual image quality ATCM settings when tube current was not restricted by the maximum value. The contrasts were independent of ATCM image quality setting, but CNR increased at the higher image quality level as image noise decreased. Both contrast and CNR decreased with increasing tube voltage for PVC and PE, but increased for POM and Acrylic. PVC was only insert material for which there was a significant improvement in contrast at lower tube potentials. Conclusions FOM indicated that Standard (SD=10) and Low dose (SD=12.5) ATCM settings might be appropriate. The optimum tube voltage settings for imaging the PVC was 80 kV-100 kV, but not for the lower contrast POM and Acrylic, for which the standard tube voltage setting of 120 kV was better. Tube potential should be carefully set to gain radiological protection optimization and keep radiation dose as low as possible. Results indicate 100 kV is likely to be appropriate for imaging small and medium sized Thai patients when iodine contrast is used.

Background To study radiation dose, image quality and low-contrast cylinder detectability from multislice CT (MSCT) abdomen by using low tube voltage using the American College of Radiology (ACR) phantom. The ACR phantom (low-contrast module) was scanned with 64 MSCT scanner (Brilliance, Philips Medical System, Eindhoven, Netherlands) with 80 and 120 KVP, utilizing different tube current time product (mAs) range from 50 to 380 mAs. The image noise (SD), signal to noise ratio, contrast-to-noise ratio (CNR), and scores of low contrast detectability were assessed for every image respectively. Results From images analyses, the noise essentially increased with the use of low tube voltage. The CNR was 0.94 ± 0.27 at 120 KVP, and CNR was 0.43 ± 0.22 at 80 KVP. However, with the same dose, there were no differences of statistical significance in scores of low-contrast detectability between 120 KVP at 300mAs and 80 KVP at (200–380) mAs (p > 0.05). At 300 mAs, the CTDIvol obtained at 80 KVP was about 29% of that at 120 KVP. The CTDIvol obtained at 80 KVP were decreased from 5% at 50 mAs, to 37% at 380 mAs. Conclusions There is a possibility to decrease exposure of radiation virtually by reducing KVP from 120 to 80 KVP in examination of abdominal CT when the high tube current is used, though increasing image noise at low tube voltage.

In recent years, nitrogen vacancy (NV) centers have shown great potential for application in quantum sensor research due to their high sensitivity to magnetic fields and excellent spatial resolution. However, in practical applications, it is necessary to eliminate environmental requirements and bulky instruments brought by the optical detection of magnetic resonance (ODMR) measurement method.. In this paper, we propose an efficient portable magnetometer with a miniature confocal system (CSPM) to resist background noise and improve integration. The confocal system can automatically focus, and the volume is limited to 11 cm3. Moreover, a fiber optic flange, an antenna and a homemade integrated photodetector are integrated in the magnetometer to achieve the actual sensitivity of sub-40 nT/Hz1/2. In the experimental process of optimizing system parameters, we discovered the important influence of beam focusing or microwave uniform operation on the detection signal and proposed specific optimization methods, which have guiding significance for future integrated design. Through comparative experiments with an integration scheme that does not use uniform operation, we found that the CSPM reduces the system noise by 4.2 times and that the signal-to-noise ratio (SNR) increases by 6.2 dB.

The plenoptic imaging technique provides a promising approach to the non-invasive three-dimensional measurement, especially for the high-temperature combustion diagnosis. We establish a light-field convolution imaging model for diffusion flame in this work, considering the radiation transfer process inside the diffusion flame and the light transfer process inside the focused plenoptic camera together. The radiation transfer process is described by the radiation transfer equation and solved by the generalized source multi-flux method. Wave optics theory is adopted to describe the light transfer process, combining Fresnel diffraction and the phase conversion of the lens. The flame light-field image is obtained by the light-field convolution imaging model and adopted as the measurement signal to reconstruct three-dimensional temperature field. The inverse problem of temperature reconstruction is solved by the least square QR decomposition method. The simulative temperature reconstruction work is conducted, including the inverse analysis, the uncertainty analysis, and the measurement noise influence. All the results show that the proposed measurement method is available to reconstruct three-dimensional temperature with satisfactory accuracy and acceptable uncertainty. Both symmetric and asymmetric distributed temperature fields are investigated, and the reconstructed results prove the validity and universality of the measurement method.

The scalable synthesis and transfer of large-area graphene underpins the development of nanoscale photonic devices ideal for new applications in a variety of fields, ranging from biotechnology, to wearable sensors for healthcare and motion detection, to quantum transport, communications, and metrology. We report room-temperature zero-bias thermoelectric photodetectors, based on single- and polycrystal graphene grown by chemical vapor deposition (CVD), tunable over the whole terahertz range (0.1-10 THz) by selecting the resonance of an on-chip patterned nanoantenna. Efficient light detection with noise equivalent powers

The temperature-dependent polarization induced bias drift is a major factor affecting the long-term zero-bias stability of integrated optic gyro (RIOG). The silicon nitride (Si3N4) with high-aspect-ratio core geometry allows high polarization extinction ratio and ultra-low propagation loss. We start from suppressing the polarization noise of the RIOG and design a single polarization Si3N4 waveguide ring resonator (WRR) with a radius of 17.5 mm. We established the polarization model of the WRR. It is found through simulation that when the polarization-dependent loss of the Si3N4 waveguide reaches 800 dB/m, it can maintain the single-polarization performance, thereby suppressing the polarization noise of the gyroscope. And the relationship between the coupling coefficient of the coupler and the limit sensitivity, finesse and transmittance was determined. The cross-sectional size of the Si3N4 WRR is determined to be $4\,\,\mu \text{m}\,\,\times 40$ nm simultaneously by simulation. Finally, through its processing and testing, a single-polarization WRR with a finesse of 127, the quality factor is $1.31\times 10 ^{7}$ , a transmission loss of 2.5 dB/m, and a polarization-dependent loss of 810 dB/m is obtained. Meanwhile, we prove its single-polarization performance at different temperature. The successful design and fabrication of the WRR is expected to achieve high precision RIOG.

Avalanche photodiodes (APDs) are used in optical receivers of high-speed optical communication systems to improve signal-to-noise ratio over conventional photodiodes. Low excess noise characteristics are crucial for APDs to preserve the benefits associated with high internal gains. In this work, we presented room temperature data of avalanche gain and excess noise factors of Al0.85Ga0.15As0.56Sb0.44 APDs using pure and mixed carrier injection profiles. Using pure electron injection, the best possible excess noise performance for a given avalanche width was measured with an excess noise factor https://doi.org/10.15131/shef.data.15082455 )

In this paper, we report the performance evaluation of praseodymium doped fiber amplifier (PDFA) operating in 1.25–1.35 μm band of wavelengths based on theoretical simulation. The performance of the PDFA is evaluated by considering an optimized length of Pr $$^{3+}$$ doped fiber, concentration of Pr $$^{3+}$$ ions and pump power. Moreover, the impact of input signal wavelength on gain, amplified spontaneous emission (ASE) noise and noise figure (NF) of the amplifier is also investigated. A small signal peak gain of around 22.7 dB is achieved at 1.3 μm for Pr $$^{3+}$$ doped fiber having short length of 15.7 m at an optimized pump power of 300 mW. A minimum NF of 4 dB is observed at 1.284 μm.

In this paper, a low voltage bandgap reference circuit has been proposed. The introduction of a modified beta multiplier bias circuit decreased the mismatch caused by the PMOS transistors opamp con...

This research introduces a closed-loop method to improve the zero-rate output (ZRO) stability of amplitude-modulated (AM) capacitive MEMS gyroscopes, even in absence of quadrature compensation electrodes. The method relies on the direct measurement and closed-loop compensation of the variation of the relative phase between the quadrature output, modulated by the drive carrier frequency, and the demodulation reference. The closed loop includes a phase meter, whose output regulates the phase of the lock-in amplifier inside the sense-mode, open-loop, demodulation chain. The proposed technique, tested on the pitch axis of a consumer-grade commercial monolithic 3-axis gyroscope, brings up to 300-fold stability improvements over temperature transients, without affecting noise and scale-factor performance. Stability limits depend on the phase meter resolution and on the lock-in granularity in regulating the phase. Overall, a mdps/K stability is obtained with a one-time calibration at ambient temperature and no post-acquisition processing. [2021-0049]

We derive a complete set of expressions for the MOSFET gate and drain power spectral densities due to elastic and inelastic trapping/detrapping of channel carriers into the gate dielectric. Our calculations explain trapping/detrapping noise (TDN) in various FET operating regions and highlight trap’s position-dependent terms, often neglected in the literature, which are instead important for devices with thin gate dielectrics. Furthermore, we show that TDN has a contribution to the gate current noise, correlated with the drain current fluctuations and we highlight the role of the transfer function between channel charge fluctuations and drain current on the noise characteristics. The model expressions are carefully validated by comparison with 2-D and 3-D TCAD simulations of scaled MOSFETs with different architectures (bulk, fully depleted-silicon-on-insulator (FD-SOI), FinFET), channel, and gate materials. Besides shedding new light on TDN, the results could enable trap density extraction from experimental samples with improved accuracy and pave the way to complete and accurate compact models for TDN in MOSFETs.

In this article, we first measured through glass via (TGV) noise coupling and the effectiveness of shielding structures in a glass interposer. To analyze the noise coupling between signal TGVs, an open-ended structure is adopted. Glass interposer test vehicles were fabricated to verify the noise coupling between signal TGVs. With these test vehicles, noise transfer functions between signal TGVs were measured. Based on these measurement results and the equivalent circuit model, the noise coupling between signal TGVs was analyzed. To suppress this TGV noise coupling, shielding structures for the TGV noise coupling were proposed and verified. The proposed shielding structures include the variation of signal TGV pitches and the number of grounded shield TGVs, ground pads, and guard rings, respectively. The effectiveness of the proposed shielding structures was verified up to 20 GHz in frequency-domain measurements. Using the proposed shielding structures, the noise transfer function decreased by 9.4 dB at 5 GHz. Also, the effectiveness of the proposed guard ring structure was verified by a time-domain coupling noise simulation with clock signals at frequencies of 1 GHz. The proposed guard ring successfully suppressed the clock noise coupling between signal TGVs by 60.5% and 69.2% when a signal TGV pitchis 300 and 900 $\mu {\text{m}}$ , respectively.

Conventional compression refrigeration systems generate considerable noise and vibration. The noise results in serious, negative impacts on people. Thermoelectric refrigeration technologies are considered a potential way to overcome these challenges. A novel thermoelectric refrigeration system, wherein thermoelectric chips are coupled with ionic wind fans, is proposed. Its performance was experimentally investigated and compared with theoretical results. The actual operating noise of the thermoelectric refrigeration system is only 4.2 dB(A), which is much lower than the maximum noise value that does not affect sleep. From experiments under different operating conditions, the optimal operating voltage of the thermoelectric chip is 5.5 V at 283.15 and 313.15 K on the cold and hot sides. The maximum coefficient of performance (COP) values reaches 0.28 and 0.31, which are equivalent to those of a system coupled with mechanical fans. Additionally, an ionic wind fan has an optimal operating voltage of 10.8 kV to maximize its air supply efficiency. Notably, such an operating voltage might be distinguished from the optimal voltage that achieves maximum operational performance for the new system. When the operating voltage of the thermoelectric chip is 5 V, the optimal operating voltage to obtain a maximum COP of 0.31 is 11.1 kV. Moreover, the experimental refrigeration capacity is greater than 8 W. The new system shows the ultra-quiet ability to operate at a large refrigeration capacity, and has good potential in applications, such as advanced refrigeration, building air-conditioning and ventilation systems.

Stabilization of residual point defects at the finishing stages of noise diodes can be ensured by the selection of appropriate ignition modes and the environment of its conduct. The method and technology of reducing the concentration of point defects in the structure of p-n-transition, taking into account the content of impurities of secondary metals, oxygen and nitrogen is proposed. It has been established that the burning of readymade structures and diodes of noise generators in nitrogen environments at temperatures of 450…600 °С for (80 ± 3) min leads to an increase in spectral noise density and a significant (twice) reduction of its unevenness. The most important result of this burn is a reduction in the spread of the average values of the noise parameters studied: by 61.2 % in effective noise voltage; spectral density by 34.2 %; at the boundary frequency of the signal by 34.9 %; in non-linear density by 25.9 %. This improves the quality of random numerical sequences in information protection software systems.

We demonstrate a hybrid solution for simultaneous transfer of ultra-stable optical frequency, RF frequency and time signal on a 100 km fiber spool with the same wavelength based on coherent demodulation and optical phase-lock-loop (OPLL). The one pulse per second (1PPS) is encoded by phase and RF frequency is encoded with an intensity modulator. The noise caused by fiber link is compensated by the round-trip method. And the bad effect on optical frequency caused by optical phase modulation (PM) can be cleaned using OPLL. When the fiber link is stabilized, the transferred time deviation (TDEV) can be 2.4E-11@1s and 1.9E-12@104s, RF frequency stability can achieve 8.0E-14@1s and 2.5E-17@104s, the modified Allan deviation (MDEV) of cleaned optical frequency can be 1.4E-16@1s and 1.6E-19@104s.