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In this paper, we present the first CMOS SPAD with performance comparable or better than that of the best custom SPADs, to date. The SPAD-based design, fully integrated in 180 nm CMOS technology, achieves a peak PDP of 55% at 480nm with a very broad spectrum spanning from NUV to NIF and a normalized DCR of 0.2cps/m2, both at 6V of excess bias. Thanks to a dedicated CMOS pixel circuit front-end, an afterpulsing probability of about 0.1% at a dead time of3ns were achieved. We designed three SPADs with a diameter of 25, 50, and 100m to study the impact of size on the timing jitter and to create a scaling law for SPADs. For these SPADs, a SPTR of 12.1ps, 16ps, and 27ps was achieved at 6V of excess bias, respectively. The SPADs operate in a wide range of temperatures, from -65C to 40C, reaching a normalized DCR of 1.6 mcps/m2 at 6V of excess bias. The proposed SPADs are ideal for a wide range of applications, including LiDAR, super-resolution microscopy, QRNGs, QKD, fluorescence lifetime imaging, time-resolved Raman spectroscopy, to name a few.

This paper reviews materials and structural approaches that have been developed to reduce the excess noise in avalanche photodiodes and increase the gain-bandwidth product.

The following paper is devoted to an amplifier with gain control (Variable Gain Amplifier). The role of amplification and gain control is addressed separately from the very beginning, to achieve the greatest possible independence of the required parameters both for the amplifier itself (gain size, bandwidth, noise figure) and for the gain controller (energy consumption control, distortion). This feature is very convenient and is not common with other VGA amplifiers. The core of the amplifier consists of an operational amplifier with voltage feedback (VFB) in an inverting circuit, to the feedback of which a gain regulator executed with a diode bridge is connected in parallel. The analysis of the simplified circuit model shows that it is possible to obtain a variable-gain amplifier that maintains its bandwidth. The control of the gain is continuous and only one element, the variable resistance, is sufficient for its control. Continuous control with one element preserving the bandwidth of an operational amplifier with VFB is unique and the authors are unaware of any other similar solution. The proposed VGA amplifier also excels in low noise and negligible distortion. If maximum gain is required, the diode bridge is disconnected and does not contribute to the resulting noise of the VGA amplifier. Because the diode bridge is connected between the output of the operational amplifier and its inverting input, and because the inverting input is current controlled, the diode bridge processes only a portion of the output voltage of the amplifier, thus preventing more noticeable distortion. The distortion is further suppressed due to the simultaneous action of four diodes in the bridge, whose characteristics are reciprocal for the signal path. The presented construction is relatively simple and can be a topic not only for other microelectronic structures, but also for applications from discrete components. The achieved parameters of the presented connection are as follows: gain change 0 to 20 dB, constant bandwidth 7 MHz, distance III. harmonics min. 30 dB at an output voltage of 0.5 V, maximum power spectral density at the output 25 $\cdot 10^{-15}\,\,\text{V}^{2}$ Hz−1.

A pole‐converging X‐band low‐noise amplifier (LNA) using 130 nm CMOS technology is proposed. An on‐chip pole‐converging capacitor CPC is added between the gate and drain node of the common‐gate (CG) stage. The capacitor CPC combines with a noise‐reducing inductor L1 to converge poles into the desired band, which results in a pole‐converging effect and wideband performance. The proposed modified broadband simultaneous noise and input‐matching technique is adopted in triple‐cascode configuration to realize good input matching and a low noise figure (NF). Measurement results exhibit a flat maximum power gain of 17.6 dB from 8 to 12 GHz and a reverse isolation over 60 dB within the desired bandwidth along with an NF ranging from 1.5 to 3.6 dB. The LNA core dissipates 17 mW from 2.4 V supply, and the chip size occupies 1.1 × 0.9 mm2 including all pads. The simulated and measured results show good agreement from 8 to 12 GHz.

In this paper a transimpedance amplifier is presented, which features a bandwidth of 97 GHz, 66 dBΩ maximum transimpedance gain, and 6.3 pA/√Hz integrated noise current density, operating at up to 120 Gb/s and consuming only 145mW. Reaching a higher bandwidth at a noise performance comparable to the state-of-the-art, is the novelty of this work. It was achieved by combining a low-bandwidth input stage, reducing the total noise, and a multi-stage post equalization. The gain peaking technique through cascading emitter follower stages is employed in a broadband transimpedance amplifier as a post equalizer. To the best of the author’s knowledge, the presented design shows the best performance in terms of overall gain, bandwidth, and noise for the lowest power consumption compared to state-of-the-art designs.

Covert communication is critical to guarantee a strong security and secure user privacy. In this work, we consider adversary’s noise and channel uncertainties and analyze their impact on adversary’s optimum detection performance and the throughput of covert messages. We determine the throughput of covert messages and its gain and loss by having adversary’s channel uncertainty and fading channel, respectively. The results show that fading is essential to hide information, particularly for low noise uncertainty or at high SNR. The improvement of adversary’s optimum detection performance, hence the covert throughput, under channel uncertainty is more significant for larger noise uncertainty. The covert throughput is gained by having channel uncertainty roughly 12–19% when the noise uncertainty is about 1–2 dB.

This work introduces a new low‐noise current‐reused CMOS active inductor (AI) based on Gyrator‐C configuration. In the proposed AI, a simple common‐source amplifier is utilised for boosting effective Gm and improving noise performance of the AI. While the Gm‐boosting technique improves the noise performance as well as the quality factor of the inductor, a resistor is also added to the feedback path for more quality factor improvement. Rigorous analysis of the proposed circuit shows a significant noise performance and quality factor enhancement. In order to verify the concept and confirm the mathematical analysis, the AI is designed and simulated in a commercial 0.18 μm RF‐CMOS technology. The simulation results show that the proposed inductor operates in 1 to 7.2 GHz frequency range, has a 9 nH inductance at 2.864 GHz frequency and 650 μW total power dissipation at 1.8‐V supply voltage. Maximum quality factor of 90 is achieved at 2.864 GHz frequency and a quality factor greater than 40 is obtained from 2.4 to 3.3 GHz. The input‐referred current noise of the proposed inductor is as low as 22 pA/√Hz showing 30.5% improvement compared to the conventional AI. The proposed AI is also tunable and sweeping the tuning voltage results in changing extracted inductance from 4.35 to 15.2 nH with only a chip area of 0.003 mm2. Post‐layout and different Monte Carlo simulation results also confirm the robust operation of the proposed AI against different process non‐idealities.

Wireless communication is a constantly evolving and forging domain. The action of the RF input module is critical in the radio frequency signal communication link. This paper discusses the design of a RF high frequency transistor amplifier for unlicensed 60 GHz applications. The Transistor used for analysis is a FET amplifier, operated at 60GHz with 10 mA at 6.0 V. The simulation of the amplifier is made with the Open Source Scilab 6.0.1 console software. The MESFET is biased such that Sll = 0.9

An oscillator noise model distinguishes between various noise sources and predicts their influence on voltage-controlled oscillator (VCO) single sideband noise. Tuning diodes are the most critical elements. A test oscillator validates the predicted performance. An equivalent noisy resistor is introduced as a figure of merit for low noise diodes. Finally, the important fabrication considerations for low noise diodes are presented and validated in the test oscillator. At 10 kHz offset, the noise contribution of optimized tuning diodes in the oscillator adds only 10 dB of noise compared to a fixed capacitor design.

This brief presents a 4th-order continuous-time analog filter based on Flipped-Source-Follower stage. Source-Follower (SF) filters typically adopt pseudo-differential topology (critical for matching and bulk/substrate noise rejection) and are realized in not recent CMOS processes (130nm or 180nm) due to the intrinsic voltage headroom required by SF operation. The proposed device solves the above limitations by proposing a fully-differential circuital topology, which improves by 13 dB the power supply rejection with respect to pseudo differential approach, and by operating in 28nm-CMOS process, thanks to a proper level-shifter transistor, which enables optimum biasing point and enhances filter dynamic range. The prototype is composed by the cascade of two biquadratic cells. It features 90 MHz −3 dB bandwidth, and consumes 816 $\mu \text{W}$ power (408 $\mu \text{W}$ per cell) from a 1V supply. Dynamic-Range is 64 dB with 140 $\mu \text{V}_{\mathrm{ RMS}}$ output noise, and at 0.32 V0-PEAK differential output voltage swing. Figure-of-Merit is 156 dBJ $^{-1}$ .

The inability to exhaust airborne formaldehyde and other volatile organic compounds from a gross anatomy laboratory is an impediment to gross anatomical education. Despite the importance of removing harmful airborne chemicals, there is scant information regarding how to build effective local exhaust ventilation systems. In this study, various exhaust systems were built and assessed for exhaust flow, airborne formaldehyde removal, and noise production with the aim of identifying inexpensive and simple exhaust systems that can create a healthy and quiet exhaust flow from a downdraft dissection table. The results of the study include details regarding 11 local exhaust ventilation systems, including an exhaust system that produces an exhaust flow of 777cfm, allows no detectable airborne formaldehyde (0ppm) despite a 1000mL pool of formalin (composed of 37% formaldehyde) positioned directly beneath a formaldehyde-meter, and operates at a very low noise level (maximum of 69.2dBA with coexisting baseline room noise of 38.6dBA). Furthermore, the aforementioned local exhaust ventilation system costs less than $400 (USD) to build and can be assembled in a matter of minutes with minimal know-how. The local ventilation systems assessed in this study were capable of down-drafting air away from the breathing zone; therefore, the utilization of such local ventilation systems may have the additional benefit of decreasing the person-to-person transmission of aerosolized pathogens. This information marks an improvement in laboratory health and safety measures, facilitates the creation of gross anatomy laboratories, and improves access to gross anatomical education.

Purpose This study aims to present two stage pseudomorphic high electron mobility transistor-based low noise amplifier (LNA) designed using low temperature co-fire ceramic (LTCC) technique for ultra-high frequency (UHF) band. The LNA operates in the frequency range of (400∼500) MHz which is suitable for wireless communication applications. Design/methodology/approach This LNA uses resistive capacitive (RC) feedback in the first stage to have wide bandwidth and interstage network for gain enhancement. By using external RC feedback, stability is improved and noise matching in the input stage is isolated by decoupling inductor. The excellent performance parameters including gain, noise figure (NF), wideband and linearity are attained without affecting the power consumption, compactness and cost of the proposed design. Findings Simulation is carried out using advanced design software and the result shows that gain of 33.7 dB, NF 0.416 dB and 1 dB compression point (P1dB) of 18.59 dBm are achieved with a supply voltage of 2.5 V. The return loss of input and output are −19.3 dB and −10.5 dB, respectively. From the above aforementioned parameters, it is confirmed that the proposed LNA is a promising candidate for receivers where high gain and very low NF are always demandable with good linearity for applications operating in the UHF band. Originality/value The innovation of the proposed LNA is that the concurrent attainment of high gain, low NF, wideband, optimum input matching, good stability by RC feedback and interstage network using LTCC technique to achieve robustness, low cost and compactness to prove the applicability of design for wireless applications.

A multidisciplinary optimization design to simultaneously enhance the aeroacoustic and aerodynamic performance of an cooling fan is performed. The flow analysis of the cooling fan is conducted by solving three dimensional steady-state RANS equations with shear-stress transport turbulence model. Based on the results of the steady flow, aeroacoustic analysis is performed by using the Hanson and Brooks model. A multi-objective optimization is performed to simultaneously improve the efficiency and reduce the sound pressure level through an improved non-dominated sorting gentic algorithm. A Kriging surrogate model is used to approximate the function value while reducing computational cost. Series of optimum designs on the pareto front yielded increases in efficiency and decreases in the sound pressure level compared to the reference design. Through numerical analysis and experimental test, the aerodynamic efficiency is increased by 5% and the total sound pressure level is reduced by 4dB without loss of air volume for the selected optimized cooling fan. The thining of rotor boundary layer and inward load shift are the main factors to improve aerodynamic efficiency and reduce noise of the cooling fan.

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.

Urban aerial mobility (UAM) is a promising approach to improve the traffic situation in gigantic cities, which, however, may encounter significant noise pollution issues. An integrated research platform, which is being established at HKUST, to include noise generation, long-distance propagation, and perception at the observers is timely to assess the environmental impact of UAM noise and to develop low-noise designs and flight planning. A high-quality test rig in the anechoic aerodynamic facility at HKUST is employed to measure the propeller aeroacoustics and aerodynamics, and to enable the innovative noise control device and design studies. The measurements and high-fidelity simulations using an in-house computational aeroacoustics solver can lead to comprehensive databases to facilitate and validate the development of physics-oriented noise prediction models. Also, high-efficient implementation of the boundary element method is conducted to account for the noise scattering due to the fuselage and then to evaluate the impact of UAM layout on the directivity patterns, which will then be efficiently projected to the far-field observers using the advanced Gaussian beam tracing with the effects due to moving source, atmospheric attenuation, and refraction, complex boundary absorption and reflection incorporated. Low-noise flight planning is then be made accordingly.

Due to the increasing bypass ratios of modern engines, the fan stage is increasingly becoming the dominant source of engine noise. Accordingly, it is becoming more and more important to develop not only efficient but also quiet fan stages. In this paper the noise emission of a fan for an aero-engine with a bypass ratio of 19 is reduced within a multidisciplinary design optimization (MDO) by means of an hybrid noise prediction method while at the same time optimizing the aerodynamic efficiency. The aerodynamic performance of each configuration in the optimization is evaluated by stationary Reynolds-Averaged Navier-Stokes (RANS) simulations. These stationary flow simulations are also used to extract the aerodynamic excitation sources for the analytical fan noise prediction. The resulting large database of the optimization provides new insights into which extent an MDO can contribute to the design of both quiet and efficient fan stages. In addition to that the hybrid approach of numerical flow solutions and analytical description of the noise sources enables to understand the noise reduction mechanisms. In particular, the influence of rotor blade loading on the aerodynamic efficiency and the noise sources as well as the potential of configurations with a comparatively low number of outlet guide vanes (OGV) is explored. The acoustic results of selected configurations are confirmed by unsteady RANS simulations.

Noise pollution is one of the major concerns in big cities as well as in the crowded area of small cites, Gorakhpur is fastgrowing city and has many locations with high noise levels. Various crossroads and intersections have traffic issues this causes high noise level. In this study, three locations were selected for noise level assessment, nearby areas of Gorakhnath Temple, BRD medical college and MMMUT. These locations are educational (silent) and low noise level zone but because they situated near traffic roads, which cause high noise levels around them. In this study outside periphery of educational institutions noise level increases due to traffic. Noise level is found to be high due to large number of human activities.

Background The topology of metabolic networks is both well-studied and remarkably well-conserved across many species. The regulation of these networks, however, is much more poorly characterized, though it is known to be divergent across organisms—two characteristics that make it difficult to model metabolic networks accurately. While many computational methods have been built to unravel transcriptional regulation, there have been few approaches developed for systems-scale analysis and study of metabolic regulation. Here, we present a stepwise machine learning framework that applies established algorithms to identify regulatory interactions in metabolic systems based on metabolic data: stepwise classification of unknown regulation, or SCOUR. Results We evaluated our framework on both noiseless and noisy data, using several models of varying sizes and topologies to show that our approach is generalizable. We found that, when testing on data under the most realistic conditions (low sampling frequency and high noise), SCOUR could identify reaction fluxes controlled only by the concentration of a single metabolite (its primary substrate) with high accuracy. The positive predictive value (PPV) for identifying reactions controlled by the concentration of two metabolites ranged from 32 to 88% for noiseless data, 9.2 to 49% for either low sampling frequency/low noise or high sampling frequency/high noise data, and 6.6–27% for low sampling frequency/high noise data, with results typically sufficiently high for lab validation to be a practical endeavor. While the PPVs for reactions controlled by three metabolites were lower, they were still in most cases significantly better than random classification. Conclusions SCOUR uses a novel approach to synthetically generate the training data needed to identify regulators of reaction fluxes in a given metabolic system, enabling metabolomics and fluxomics data to be leveraged for regulatory structure inference. By identifying and triaging the most likely candidate regulatory interactions, SCOUR can drastically reduce the amount of time needed to identify and experimentally validate metabolic regulatory interactions. As high-throughput experimental methods for testing these interactions are further developed, SCOUR will provide critical impact in the development of predictive metabolic models in new organisms and pathways.

The reset noise sampling feedforward (RNSF) technique is proposed in this paper to reduce the noise floor of the readout circuit for micro-electromechanically systems (MEMS) capacitive accelerometer. Because of the technology-imposed size restriction on the sensing element, the sensing capacitance and the capacitance variation are reduced to the femto-farad level. As a result, the reset noise from the parasitic capacitance, which is pico-farad level, becomes significant. In this work, the RNSF technique focuses on the suppression of the parasitic-capacitance-induced noise, thereby improving the noise performance of MEMS capacitive accelerometer. The simulation results show that the RNSF technique effectively suppresses the thermal noise from the parasitic capacitance. Compared with the traditional readout circuit, the noise floor of the readout circuit with the RNSF technique is reduced by 9 dBV. The presented circuit based on the RNSF technique is fabricated by a commercial 0.18-μm BCD process and tested with a femto-farad MEMS capacitive accelerometer. The physical measurement results show that, compared with the readout circuit without the RNSF technique, the RNSF technique reduces the noise floor of the readout circuit for MEMS capacitive accelerometer from −72 dBV to −80 dBV. Compared with other similar works, the proposed readout circuit achieves better FoM(FoM=(power×noisefloor)/systembandwidth=490μW·μg/Hz) among the switched-capacitor readout circuits.