Low Noise Power Research Articles

Model-Based Causal Feature Selection for General Response Types

Discovering causal relationships from observational data is a fundamental yet challenging task. Invariant causal prediction (ICP, Peters, Bühlmann, and Meinshausen) is a method for causal feature selection which requires data from heterogeneous settings and exploits that causal models are invariant. ICP has been extended to general additive noise models and to nonparametric settings using conditional independence tests. However, the latter often suffer from low power (or poor Type I error control) and additive noise models are not suitable for applications in which the response is not measured on a continuous scale, but reflects categories or counts. Here, we develop transformation-model (tram) based ICP, allowing for continuous, categorical, count-type, and uninformatively censored responses (these model classes, generally, do not allow for identifiability when there is no exogenous heterogeneity). As an invariance test, we propose tram-GCM based on the expected conditional covariance between environments and score residuals with uniform asymptotic level guarantees. For the special case of linear shift trams, we also consider tram-Wald, which tests invariance based on the Wald statistic. We provide an open-source R package tramicp and evaluate our approach on simulated data and in a case study investigating causal features of survival in critically ill patients. Supplementary materials for this article are available online, including a standardized description of the materials available for reproducing the work.

One-third octave spectrum calculation to meet the attenuation limits of a Class 1 analyzer (IEC 61260-1:2014) for low-power noise sensors

Thanks to the advances in technology and the cost reductions of electronic components, nowadays it is possible to produce low-cost and low-power acoustic sensors with extended capabilities such as the one-third octave band spectrum calculation. However, there are some doubts about the accuracy of these devices. Thus, to meet the attenuation limits of a Class 1 analyzer for low frequencies as stated in IEC 61260-1:2014 normative, this research proposes two algorithms to calculate the one-third octave band spectrum, both algorithms are based on the Power Spectral Density (PSD). The first one consists of a subdivision of frequency bins, where a PSD bin is divided into smaller parts, gain adjusted, and assigned to its corresponding one third-octave band. The other one is based on signal decimation-accumulation, where samples, that are processed every 125 ms due to the sensor design, are first decimated and then accumulated to increase the frequency bin resolution. Both algorithms are programmed into the sensor and the power consumption and acoustical performance are evaluated and compared to a typical multi-rate filter bank. It is observed that both proposed algorithms improve the performance of the low-cost sensor in terms of energy consumption and accuracy.

Research on the influence of different organizational structures on the electrical life of sealed relays

Abstract A sealed relay is a type of power relay mainly used in fields with harsh environments, low noise requirements, or high-reliability requirements. It is used in scenarios such as vehicle loads, household appliances, industrial control, and motors. At the same time, when the input meets certain specified conditions, it is a device that can generate a jump in one or more electrical output circuits, playing a role in controlling the on/off current of the connected circuit. Power relays have been widely used in various fields due to their small size, low noise, and low power consumption advantages. This article mainly studies the electrical parameters such as arc energy, arc time, welding force, and contact burning principle of silver tin oxide electrical contact materials produced by different processes, providing a reference for the development of electrical contact materials.

A low power low phase noise wide frequency range PLL

This paper presents a low-noise, low-power, wide output frequency range phase-locked loop (PLL) for WLAN/WiFi transceivers. By employing a dual-symmetric CMOS cross-coupled pair differential inductor voltage-controlled oscillator (VCO), the design achieves low phase noise. In addition, an improved phase frequency detector (PFD) and a programmable low-mismatch charge pump (CP) with feedback compensation bias control are used to mitigate bandwidth and noise variations caused by different reference frequencies. The improved charge pump PLL (CPPLL) is designed in 65 nm CMOS process, and the chip layout occupies an area of 0.28 mm2. Post-layout simulation results indicate that the PLL has a tuning range of 4.6 GHz to 6 GHz, a phase noise of 111.7 dBc/Hz at 1 MHz offset at 5 GHz, a total power consumption of 7.14 mW, and a lock time of about 9μs.

Pico-ampere resolution current measurement circuit using Gm-C filter sigma-delta modulator for low-power nanopore DNA sequencing

New generation DNA sequencers use an array of electrochemical cells equipped with nanopores, which produce pico-ampere current levels. Due to the large number of channels, low current levels and bandwidths in the order of a few kHz, in the design of these readout circuits, 2D arrays of in-channel, low noise and low power analog to digital converters are preferred. Previously many different sigma-delta modulators have been presented to convert the nanopore current signal into a digital code. Conventionally, the opamps required in these converters will eventually increase the power dissipation of each channel. In this paper a novel Gm-C filter based second order sigma-delta converter is proposed. In the given design, rather than relying on multiple opamps to achieve the necessary gain and noise performance, only a 4 transistor Gm block is used. Evaluations show that while the input referred noise remains close to previous methods, the power dissipation is considerably reduced. A prototype is also implemented to show the effectiveness of the approach. In a 180-nm design, an ENOB of 12.16 bits, RMS input referred noise of 0.2 pA at 10 kHz bandwidth and power dissipation of 8.27 μW is obtained per channel.

High-efficiency, single-frequency, polarized thulium-doped silica fiber lasers.

We report on single-frequency, linearly polarized, high-concentration thulium-doped silica fiber-distributed Bragg reflector lasers operating at wavelengths between 1908 and 2050 nm with high efficiencies up to 48% and high powers up to 1 W. Low relative power noise and frequency noise are demonstrated using a low-noise pump diode.

A low power and low noise bandgap reference design

A low power and low noise bandgap reference design

16-channel 200-GHz-spacing RW-DFB laser array with low noise and high output power

We experimentally demonstrated a ridge waveguide (RW) distributed feedback (DFB) continuous-wave (CW) laser array with high output power, low relative intensity noise (RIN) and narrow linewidth for all 16 channels with 200-GHz-spacing. The ridge waveguide is formed above an offset-quantum-well structure to increase single transverse mode waveguide width to 8-µ;m for higher output power and lower noise. A relatively long cavity length of 800-µm as well as a backup laser technique are introduced to achieve good single mode stability. The fabricated RW-DFB laser array realizes the maximum power over 85 mW, RIN lower than -155 dB/Hz and Lorentzian linewidth below 250 kHz for each channel laser. Besides, the side mode suppression ratio (SMSR) is over 51 dB for all 16 channels. These features can help to boost the application in wavelength dimension multiplexed system.

Field-theoretic approach to neutron noise in nuclear reactors.

An operating nuclear reactor is designed to maintain a sustained fission chain reaction in its core, which results from a delicate balance between neutron creations (i.e., fissions) and total absorptions. This balance is associated with random fluctuations that can have two, very different, origins. A distinction must thus be made between low-power noise, whose origin lies in the inherently stochastic nature of neutron interactions with matter, and high-power noise, whose origin lies in the particular thermomechanical constraints associated with the environment in which neutrons propagate. Modeling the behavior of this noisy neutron population with the help of stochastic differential equations, we first show how the Martin-Siggia-Rose-Janssen-De Dominicis (MSRJD) formalism, providing a field theoretical representation of the problem, reveals a convenient and adapted tool for the calculation of observable consequences of neutron noise. In particular, we show how the MSRJD approach is capable of encompassing both types of neutron noises in the same formalism. Emphasizing then on power noise, it is shown how the self-sustained chain reaction developing in a reactor core might be sensitive to noise-induced transitions. Establishing an unprecedented connection between the neutron population evolving in a reactor core and the celebrated Kardar-Parisi-Zhang (KPZ) equation, we indeed find evidence that a noisy reactor core power distribution might be subject to a process analogous to the roughening transition, well-known to occur in systems described by the KPZ equation.

An ultrahigh input impedance low noise analog front‐end design for epilepsy brain recording system

SummaryThis paper presents an ultrahigh input impedance, low noise, and wide bandwidth four‐channels analog front‐end (AFE) for low‐power neural recording systems. To achieve high input impedance, the buffer channels are placed between the electrodes and the main amplifier stage of the AFE. The buffer is designed with low noise and low power consumption to obtain high input impedance of overall AFE while maintaining low input‐referred noise and low power consumption. A chopper capacitively coupled chopper instrumentation amplifier (CCIA) is placed after the buffer as the main amplifier stage of the AFE to improve the common mode rejection ratio (CMRR) and the input‐referred noise of the overall AFE design. A new chopper stabilization control technique is proposed and used in the CCIA stage to reduce the charge injection and clock feedthrough and consequently the high‐frequency ripple of the AFE output signal. A programmable gain amplifier (PGA) is designed as the third stage to adjust the overall gain of the AFE. Benefiting from PGA, the AFE can adapt its gain with both action potential and local field potential signals. To reduce the number of the electrode to be implanted and reduce the impedance mismatch that causes the degradation on overall CMRR performance, two AFE channels shared a reference electrode followed by a reference buffer. The proposed AFE is designed and simulated using a standard 180 nm CMOS process and operates in a wide frequency band of 2.1 to 2500 Hz with low input‐referred noise of 1.6 μVrms and a CMRR over 80 dB at 2.1 Hz. The total power consumption is lower than 4.3 μW per channel. With the proposed structure of AFE, the input impedance is 35 GΩ @ 21 Hz and the minimum impedance over operational bandwidth is 75 MΩ @ 2.5 kHz.

Design of low power and low phase noise LC-VCO for Bluetooth/WLAN applications

The proposed Inductor-Capacitor Voltage-Controlled Oscillator (LC-VCO) prototype design generates 2.45 GHz to 4.58 GHz of frequency using the Cadence UMC 180 nm process with a 1.8V supply. This architecture carried a new viewpoint on tank design put forth by enhancing the varactor tuning. Here, the circuit employs a CMOS differential cross-coupled pair, and rail-to-rail DC biasing achieves a higher voltage swing. Simulation analysis parameters are measured at 2.45 GHz frequency, phase noise is −123.5 dBc/1 MHz offset, power is 3.5 mW, jitter is 0.232 fsec, and it occupies 0.118 μm2 layout area. Additionally, the simulations have been extended for analysis under Process Voltage and Temperature Corners, Monte-Carlo, and Worst-Case Corners. This study obtained a better FoM of -200.94 dBc/Hz. The simulation results and FoM of the proposed design show a considerably improved than state-of-the-art framework. This LC-VCO circuit study will be suitable for implementing the sub-6 GHz charge pump phase-locked loops (CP-PLLs) system for 5G applications.

180 nm NMOS voltage-controlled oscillator for phase-locked loop applications

<p>The voltage-controlled oscillator (VCO) is the primary device in the phase-locked loop (PLL) to produce the local oscillator frequency. The excessive phase noise of VCOs is the primary cause of PLL performance loss. This paper proposes the design and optimization of low phase noise and low power consumption for a 180 nm N-channel metal-oxide semiconductor NMOS VCO for PLL applications with P-channel metal-oxide semiconductor PMOS varactors and spiral inductors. At 2 V supply voltage, the optimized NMOS VCO has a power consumption of 21 mW, a phase noise of -130 dBc/Hz at 1 MHz offset and a total harmonic distortion (THD) of 3.9%. The proposed design is verified by PSpice simulations. A new criterion is proposed for optimizing NMOS LC oscillators.</p>

High magnetic performance ultra-thin Fe-6.5Si ribbons fabricated by planner flow casting and annealing

Fe-6.5 wt.%Si steel is one of the most attractive soft magnetic materials for making iron cores with low noise and low power loss. The planner flow casting method was regarded as a promising method to obtain ultra-thin ribbons of Fe-6.5Si alloy. In this study, Fe-6.5Si ribbons with a thickness of 0.03 mm were prepared by planner flow casting. Samples were heat-treated at various temperatures. It is revealed that the grain size on the wheel surface and free surface gradually increases with increasing annealing temperature. The initial {100} fiber texture of the wheel and free surfaces is weakened after annealing, transforming to {001} 〈510〉 on the wheel surface and to {229} < 11 2 2 > on the free surface after annealing at 1150 °C for 1 h. The texture parameter and dislocation density are the key factors affecting the magnetic induction intensity, showing an inverse correlation with the texture parameter and dislocation density. Furthermore, the iron loss is mainly influenced by the grain size, with an optimal grain size of 10 μm. Considering the magnetic induction intensity and iron loss, the optimal annealing temperature is determined to be 1100 °C, resulting in a magnetic induction intensity of B8 = 1.26 T and B50 = 1.65 T, and iron loss values of P1/400 = 14.1 W/Kg and P0.2/5000 = 11.1 W/Kg.

Design analysis of a multi-port 8-shaped inductor for RF applications

Portable wireless devices with a high-frequency range should also function with low voltage, providing low power dissipation and noise. Design engineers cannot successfully meet the above design objectives without using RF inductors. Since integrated inductors are an essential part of RF circuits, these devices are highlighted because of their enormous size in the circuit layout and unsettling radiations. As a result, there is a solid motivation to design, optimize, and model inductors made on Si substrates. This article presents the design of a multi-path multi-port 8-shaped inductor with dimensions of 150 × 150 μm, simulated using Cadence EMX simulator to analyze its Q-factor and inductance. The analysis provided that the simulated inductance has the highest value of 12.2 nH, which is the maximum value across all the conclusions of this research. Another significant discovery was that this Inductor is suitable for up to 45 GHz. To achieve an improved frequency of operation for the multi-path, multi-port 8-shaped Inductor, an analysis of the Inductor’s topology is conducted, focusing on enhancing the loop widths of metal layers and optimizing spacing between the metal tracks.

Low power and low phase noise complementary voltage controlled oscillator optimised by a meta‐heuristic algorithm

AbstractThis paper presents a differential complementary metal oxide semiconductor inductor‐capacitor voltage controlled oscillator (LC‐VCO). The VCO is adopted from the gate‐to‐source capacitor feedback Colpitts VCO which has the advantage of large value of negative conductance. Due to the large negative conductance, the VCO has a more reliable startup oscillation at the lower currents. The main characteristics of the VCO such as negative conductance, oscillation frequency and phase noise are discussed and analysed. The value of parameters in this circuit have been determined using Non‐dominated Sorting Genetic Algorithm (NSGA‐II) to have the optimum performance. The designed VCO oscillates at 2.76 GHz under a supply voltage of 1.4 V. Power dissipation of the proposed VCO is 873 μW which is significantly lower than that of some other VCOs. The post‐layout simulation results of the proposed VCO are presented and compared with the performance of some other VCOs.

A low‐power voltage‐controlled oscillator with phase noise suppressing techniques

AbstractA 0.5‐V low‐power VCO by using TSMC 0.18‐μm CMOS process has been proposed. For achieving low phase noise and low power consumption, several techniques have been utilized. The forward body biasing technique can lower the supply voltage and power consumption. The noise filtering, feedback capacitors, and switched biasing technique can reduce the phase noise and power consumption. The PMOS transistors, which has lower flicker noise than the NMOS transistors, are used for further lowering the phase noise. The body‐controlled cross‐coupled pair is proposed for choosing the oscillation frequencies without using additional varactors, which lower the oscillation signal loss and phase noise. The measured results show the phase noise at 1 MHz offset frequency from the carrier signal is −118.6 dBc/Hz with 1/f3 corner frequency of 230 kHz while the control voltage is 0 V. The frequency tuning range is from 2.4 to 2.46 GHz under power consumption from 0.5 to 0.8 mW. The figure of merit at 1 MHz offset frequency from the carrier signal is −189 dBc/Hz.

A High-Performance Thin-Film Sensor in 6G for Remote Sensing of the Sea Surface

Functional devices in the THz band will provide a highly important technical guarantee for the promotion and application of 6G technology. We sought to design a high-performance sensor with a large area, high responsiveness, and low equivalent noise power, which is stable at room temperature for long periods and still usable under high humidity; it is suitable for the environment of marine remote sensing technology and has the potential for mass production. We prepared a Te film with high stability and studied its crystallization method by comparing the sensing and detection effects of THz waves at different annealing temperatures. It is proposed that the best crystallization and detection effect is achieved by annealing at 100 °C for 60 min, with a sensitivity of up to 19.8 A/W and an equivalent noise power (NEP) of 2.8 pW Hz−1/2. The effective detection area of the detector can reach the centimeter level, and this level is maintained for more than 2 months in a humid environment at 30 °C with 70–80% humidity and without encapsulation. Considering its advantages of stability, detection performance, large effective area, and easy mass preparation, our Te thin film is an ideal sensor for 6G ocean remote sensing technology.

정수기 빌트인용 SPM type BLDC 모터 토크제어를 위한 모터설계 및 약계자 제어기 설계에 관한 연구

The system for water purifiers requires a motor with a constant speed, high torque, low noise, and low power. AC motors have low starting torque, and DC motors have difficulty in replacing brushes, generate noise, and are difficult to maintain. This study uses a high-density energy magnet called a neodymium magnet to design and control an SPM brushless DC (BLDC) motor to control high torque. This paper proposes the control and design of BLDC motors using the weak field method.

An improved PVT-Robust floating inverter dynamic amplifier for noise-shaping SAR ADCs

The floating inverter dynamic amplifier (FIDA) is a power-efficient, open-loop, and dynamic amplifier without requiring any output common-mode feedback (CMFB) circuit. It is appropriate for low-power applications. However, its gain is not robust over process, voltage, and temperature (PVT) variations. In this work, a simple, low power, and low noise method is proposed to solve this problem. The proposed method controls the amplification time window of the FIDA to be proportional to its time constant. Based on the FIDA gain formula, this technique stabilizes the gain over PVT changes. The proposed PVT-robust FIDA is designed at the circuit level using 0.18 µm TSMC CMOS technology with Cadence Virtuoso tool. According to the post-layout simulation results of a sample design, the gain of the amplifier is 29.4 with 51.3 µW power consumption from a 1.2 V supply voltage. The maximum gain variation over PVT changes is reduced from 49.6% to 9.8% using the proposed gain calibration technique.

High-quality Ultrafast Power Doppler Imaging Based on Spatial Angular Coherence Factor.

The morphological and hemodynamic changes of microvessels are demonstrated to be related to the diseased conditions in tissues. Ultrafast power Doppler imaging (uPDI) is a novel modality with a significantly increased Doppler sensitivity, benefiting from the ultrahigh frame rate plane wave imaging and advanced clutter filtering. However, unfocused plane wave transmission often leads to a low imaging quality, which degrades the subsequent microvascular visualization in power Doppler imaging. Coherence factor (CF) based adaptive beamformers have been widely studied in conventional B-mode imaging. In this study, we propose a spatial and angular coherence factor (SACF) beamformer for improved uPDI (SACF-uPDI) by calculating the spatial coherence factor across apertures and the angular coherence factor across transmit angles, respectively. To identify the superiority of SACF-uPDI, simulations, in vivo contrast-enhanced rat kidney, and in vivo contrast-free human neonatal brain studies were conducted. Results demonstrate that SACF-uPDI can effectively enhance contrast and resolution, and suppress background noise simultaneously, compared with conventional uPDI methods based on DAS (DAS-uPDI) and CF (CF-uPDI). In the simulations, SACF-uPDI can improve the lateral and axial resolutions compared with those of DAS-uPDI, from 176 μm to 108 μm of lateral resolution, and 111 μm to 74 μm of axial resolution. In the in vivo contrast-enhanced experiments, SACF achieves 15.14- and 5.6-dB higher contrast-to-noise ratio (CNR), 15.25- and 3.68-dB lower noise power, and 240- and 15-μm narrower full-width at half-maximum (FWHM) than DAS-uPDI and CF-uPDI, respectively. In the in vivo contrast-free experiments, SACF achieves 6.11- and 1.09-dB higher CNR, 11.93- and 4.01-dB lower noise power, and 528- and 160-μm narrower FWHM than DAS-uPDI and CF-uPDI, respectively. In conclusion, the proposed SACF-uPDI method can efficiently improve the microvascular imaging quality and has the potential to facilitate clinical applications.