Broadband Power Research Articles

Development of a broadband and high-absorption graphene thermoelectric terahertz power meter

Development of a broadband and high-absorption graphene thermoelectric terahertz power meter

Spectral Changes in Motor Thalamus Field Potentials During Movement.

Motor thalamus plays a crucial role in integrating and modulating sensorimotor information. While voltage power spectral changes in motor cortex with movement are well-characterized, corresponding activity in the motor thalamus, particularly broadband power change, remains unclear. The present study aims to characterize spectral changes in motor thalamus during hand movements of 15 subjects undergoing awake deep brain stimulation surgery targeting the ventral intermediate (Vim) nucleus of the thalamus for disabling tremor. We analyzed power changes in subject-specific low frequency oscillations (<30 Hz) and broadband power (captured in 65-115 Hz band) of serial field potential recordings. Consistent with previous studies, we found widespread decreases in low frequency oscillations with movement. Importantly, in most subjects we observed that sites with significant increase in broadband power were more spatially discrete, primarily involving the inferior recording sites within ventral thalamus. One subject also performed an imagined movement task during which low frequency oscillatory power was suppressed. These electrophysiologic changes may be leveraged as biomarkers for thalamic functional mapping, DBS targeting, and closed loop applications.

Filtered Point Processes Tractably Capture Rhythmic And Broadband Power Spectral Structure in Neural Electrophysiological Recordings.

Neural electrophysiological recordings arise from interacting rhythmic (oscillatory) and broadband (aperiodic) biological subprocesses. Both rhythmic and broadband processes contribute to the neural power spectrum, which decomposes the variance of a neural recording across frequencies. Although an extensive body of literature has successfully studied rhythms in various diseases and brain states, researchers only recently have systematically studied the characteristics of broadband effects in the power spectrum. Broadband effects can generally be categorized as 1) shifts in power across all frequencies, which correlate with changes in local firing rates and 2) changes in the overall shape of the power spectrum, such as the spectral slope or power law exponent. Shape changes are evident in various conditions and brain states, influenced by factors such as excitation to inhibition balance, age, and various diseases. It is increasingly recognized that broadband and rhythmic effects can interact on a sub-second timescale. For example, broadband power is time-locked to the phase of <1 Hz rhythms in propofol induced unconsciousness. Modeling tools that explicitly deal with both rhythmic and broadband contributors to the power spectrum and that capture their interactions are essential to help improve the interpretability of power spectral effects. Here, we introduce a tractable stochastic forward modeling framework designed to capture both narrowband and broadband spectral effects when prior knowledge or theory about the primary biophysical processes involved is available. Population-level neural recordings are modeled as the sum of filtered point processes (FPPs), each representing the contribution of a different biophysical process such as action potentials or postsynaptic potentials of different types. Our approach builds on prior neuroscience FPP work by allowing multiple interacting processes and time-varying firing rates and by deriving theoretical power spectra and cross-spectra. We demonstrate several properties of the models, including that they divide the power spectrum into frequency ranges dominated by rhythmic and broadband effects, and that they can capture spectral effects across multiple timescales, including sub-second cross-frequency coupling. The framework can be used to interpret empirically observed power spectra and cross-frequency coupling effects in biophysical terms, which bridges the gap between theoretical models and experimental results.

Co-transmission of optically-carried 5G NR signal and over 14-W power light via standard single-mode fiber

Co-transmission of optically-carried broadband wireless communication signal and power light in standard single-mode fiber (SSMF) is the supporting technology for realizing remotely-powered antenna units in the next-generation wireless communication networks. Here, we experimentally demonstrate the co-transmission of optically-carried fifth-generation new radio (5G NR) signal and over 14-W power light via a spool of SSMF with a length of 1 km. Thereinto, the optical power transmission efficiency (OPTE), which is restricted by stimulated Brillouin scattering, is increased via extending the linewidth of the power light to 1 nm. Additionally, the in-band interference and the signal-to-noise ratio (SNR) degradation of the optically-carried 5G NR signal, which are attributed to the noise transference and the modulation instability induced by the Kerr effect and the stimulated Raman scattering effect, are suppressed through group-velocity dispersion management via carefully designing the wavelengths of the signal light and the power light. In the simulation, a 7-dB reduction in the noise floor and a significant rejection of the spurious signals are achieved via shifting the signal light wavelength from 1550 nm to 1310 nm. In the experiment, the OPTE of the power light reaches around 70%, and the received power fluctuation is smaller than 1% within 90 min. The received maximum electrical power is larger than 0.9 W with a regulated voltage of 12 V, which is sufficient to power the minimalist antenna unit. Besides, the error vector magnitude (EVM) and the adjacent channel leakage ratio (ACLR) of the received 256-level quadrature amplitude modulation (256-QAM) 5G NR signal are below 2.5% and −40 dBc, respectively. The experimental results conclusively demonstrate the feasibility of the co-transmission link to enable remote power supply for the minimalist antenna unit in the beyond fifth-generation and sixth-generation fronthaul networks.

LG = 50 nm T-gated and Fe-doped double quantum well GaN‒HEMT on SiC wafer with graded AlGaN barrier for future power electronics applications

High-performance LG = 50 nm graded double-channel (GDC)-HEMT featuring AlN top barrier, recessed T-gate and graded-AlGaN bottom barrier is designed and investigated. Two quantum wells are formed in the AlN-GaN-graded AlGaN-GaN multilayer structure developed on a SiC substrate and the clear double hump feature of the transconductance (GM), cut-off frequency (fT), and capacitance plots clearly illustrates the double-channel (DC) behavior. The investigations carried out to explore the impact of barrier thickness (both AlN & graded-AlGaN) revealed superior performance with the GM showing two peaks at 181.5 & 488.1 mS/mm, the peak-drive-current (ID_peak) with VGS biased at 3 V is 1.81 A/mm, maximum saturation drain current of 3.08 A/mm (VGS = 3V), and the fT derived from the left- and right-hump are 263.7 GHz & 354.2 GHz, respectively, when both barriers are 6 nm thin, attributable to enhanced 2DEG density due to the coordination of channels because of proximity and lower leakage. It has been noticed that when the bottom barrier is thick, the DC behaviour is less obvious due to insufficient gate access to the lower channel. We investigated the impact of varying the Al % in AlGaN top barrier on the DC/RF performance of GDC-HEMTs, demonstrating enhanced performance with increased Al content, particularly for Al0.35Ga0.65N. By using various metals, this study also investigates how gate engineering affects the electrical characteristics of the GDC-HEMT. The lower ϕm (work function) of the Al-gate led to better DC/RF performance. When the Schottky barrier rises as a result of the conduction band edge being elevated, the performance reduces, and the threshold voltage (Vth) increases. Since it is essential to comprehend the role that source resistance (Rs) & drain resistance (Rd) play in RF design, we have also conducted simulations by varying the source-gate gap (LGS) & drain-gate gap (LGD). Due to low Rs & Rd, it was determined that the GDC-HEMT performed better at the smallest LGS & LGD. The extraordinary performance strongly highlights the immense potential and applicability of the GDC-HEMTs for future broadband power amplifiers.

Knowledge-Aided Automated Synthesis for Broadband Power Amplifier With Transformer-Coupled Resonators

Knowledge-Aided Automated Synthesis for Broadband Power Amplifier With Transformer-Coupled Resonators

Research on Broadband Measurement Method of Power System based on Wavelet Transform

This study delves into the exploration of broadband measurement techniques for power systems, utilizing wavelet transform as a foundational tool for signal analysis. The research rigorously evaluates the efficacy of several machine learning algorithms, namely Support Vector Machines (SVM), Artificial Neural Networks (ANN), K-Nearest Neighbors (KNN), and Random Forest, in interpreting and analyzing broadband signals within power systems. Through a detailed analytical process, the performance of each algorithm is meticulously assessed based on several critical metrics: accuracy, precision, recall, and F1-score. The research investigates broadband measurement methods for power systems using wavelet transform and evaluates the performance of Support Vector Machines (SVM), Artificial Neural Networks (ANN), K-Nearest Neighbors (KNN), and Random Forest. Results show SVM achieving an accuracy of 85%, precision of 86%, recall of 82%, and F1-score of 84%. ANN yields 82% accuracy, 84% precision, 78% recall, and 81% F1 score. KNN demonstrates 87% accuracy, 88% precision, 84% recall, and 86% F1 score. DT achieves 79% accuracy, 80% precision, 75% recall, and 77% F1 score. Overall, the study provides insights into machine learning algorithms’ effectiveness in broadband power system measurement.

ID: 323891 Referencing Schemes and Their Effect on Oscillations and Broadband Power Spectral Shifts in Stereoelectroencephalography

ID: 323891 Referencing Schemes and Their Effect on Oscillations and Broadband Power Spectral Shifts in Stereoelectroencephalography

Analysis and suppression of offshore wind power broadband oscillation based on HVDC transmission technology

Analysis and suppression of offshore wind power broadband oscillation based on HVDC transmission technology

Bifunctional acoustic lossy coupler for broadband power splitting and absorption

In this work, we propose a bifunctional acoustic lossy coupler for broadband power splitting and absorption. Following the three-level system in quantum physics, the three-waveguide (WG) acoustic system is proposed to obtain efficient energy transfer behaviors. Given the agreement in form between Schr o¨ dinger equation and coupled mode equation, the time-dependent external fields are mapped into space-varying coupling actions between adjacent WGs. The propagation paths of the incident waves can be predicted by Schr o¨ dinger-like equation, which are verified by numerical simulations and experimental measurements. Owing to the different responses to lossy medium in WG B for WG A incidence and WG C incidence, the acoustic coupler can be considered as a broadband power splitter and muffler by selecting different input ports. Meanwhile, according to the reversibility of acoustic path, a switchable acoustic logic gate with functions of “OR” and “XOR” is constructed as well by taking advantage of the lossless adiabatic coupler, and the function can be controlled conveniently by reversing the phase of input waves from WG A or C. Our work provides a new scheme for the design of bifunctional acoustic coupler, which may have a profound impact on the development of non-resonance acoustic high-performance devices.

A 28-47.5 GHz broadband power amplifier using improved MCR technique in 40-nm CMOS

This paper presents a broadband power amplifier (PA) implemented in 40-nm CMOS process for low power application. The PA cascades two stages of common-source differential transistors and adopts symmetrical magnetically coupled resonators (MCRs) for impedance matching and single-ended differential conversion. Theoretical analysis elucidates the effect of the resonator Q on the frequency response of the transformer, thus giving the distribution of the poles and their precise locations, and revealing the quantitative relationship between bandwidth and gain ripple. A method for efficiently balancing gain ripple and bandwidth in k, Q space under low-power conditions when the intrinsic Q of the source impedance is high is described in detail. Measurement results demonstrate a 51.6% 3-dB bandwidth from 28 to 47.5 GHz. The PA achieve 10.7 dBm Psat, 8.5 dBm OP1db and 23% peak PAE at 31 GHz.

Power-efficient wideband programmable pseudo differential ring oscillator CP-PLL

A power-efficient, wide-band, programmable pseudo-differential ring-oscillator charge-pump phase-locked loop (CP-PLL) is proposed. The ring-VCO, characterized by its low power consumption and broadband, is achieved based on a feedforward pseudo-differential configuration. The linearity of ring-VCO is improved by using the source negative feedback topology. Through the rail-to-rail operatingamplifier clamping current source, the current matching accuracy is improved to realize a high-performance CP circuit. The results show that the output frequency range of the phase-locked loop is 0.6–6 GHz at a 1.2 V supply voltage, and the power consumption is 1.372 mW at 5 GHz with a lock-up time of 1.72 μs and RMS jitter of 9.3 ps. The power consumption is as low as 0.643 mW at 2.5 GHz and 1.067 mW at 4 GHz, and the final layout area is 0.00716 mm2. The implemented CP-PLL can be used effectively in wireless RF communication system of NB-IoT and intelligent edge computing scenario.

Broadband and low-loss power splitter with polarization manipulation using subwavelength gratings

A broadband and low-loss power splitter with polarization manipulation using subwavelength gratings (SWGs) is proposed and analyzed, where SWGs are embedded in input taper/output inverse tapered waveguides in the bottom layer to form an SWG-based structure, and a silicon nitride layer is placed above the bottom layer to form a low-index guiding structure. In the bottom layer, the TE mode is cut off as the input strip waveguide is tapered down. In this way, the injected TE mode is evenly coupled to two adjacent output ports with high efficiency by the assistance of SWGs. By contrast, the input TM mode is well supported by the above silicon nitride layer and directly transmitted to the Through port, which is almost not influenced by the bottom structures. Consequently, both power splitting and polarization handling are achieved in the designed device simultaneously. Simulation results show that an extinction ratio (ER) of 32.63 dB (18.56 dB) and insertion loss (IL) of 0.16 dB (0.16 dB) for the TE (TM) mode are obtained at 1.55 µm. The bandwidth is up to 191 nm (1450–1641 nm) for the TE mode and 200 nm (1450–1650 nm) for the TM mode with an ER exceeding 15 dB and IL below 0.3 dB. Furthermore, fabrication tolerances and power distribution with polarization manipulation through the device are also presented.

Design and Implementation of a Broadband, Low Voltage, and Low Power GaAs Power Amplifier

Design and Implementation of a Broadband, Low Voltage, and Low Power GaAs Power Amplifier

Controlled dispersive waves emission via swallowtail-type catastrophe pulses.

The dispersive waves (DWs) emission has emerged as an efficient way to extend the spectral range of a light source. However, the applications of the DWs are limited because of its narrowband and low power. It is crucial to find novel ways to manipulate the DWs radiation. We investigate a kind of catastrophe pulses, called swallowtail pulses, which can radiate DWs with broadband and high power. By exploiting the dependence of the temporal and spectral structure of swallowtail pulses on the initial control parameter within the catastrophe integral, we can effectively manipulate the emission of DWs in terms of resonant frequency and conversion efficiency. Furthermore, we observe that the swallowtail pulses can shed two solitons, and that both of them radiate DWs with different frequencies. In comparison to fundamental solitons, the minimum value of third-order dispersion required for the onset of DWs emission becomes significantly smaller for that of swallowtail pulses. The results of this study clearly reveal the impact of the inherent behaviors of swallowtail pulses on the DWs emission, which should be relevant for applications requiring broadband light sources and optical frequency combs based on the mechanism of DWs emission.

Prefrontal Oscillatory Slowing in Early-Course Schizophrenia Is Associated With Worse Cognitive Performance and Negative Symptoms: A Transcranial Magnetic Stimulation-Electroencephalography Study

BackgroundAbnormalities in dorsolateral prefrontal cortex (DLPFC) oscillations are neurophysiological signatures of schizophrenia thought to underlie its cognitive deficits. Transcranial magnetic stimulation with electroencephalography (TMS-EEG) provides a measure of cortical oscillations unaffected by sensory relay functionality and/or patients’ level of engagement, which are important confounding factors in schizophrenia. Previous TMS–EEG work showed reduced fast, gamma-range oscillations and a slowing of the main DLPFC oscillatory frequency, or natural frequency, in chronic schizophrenia. However, it is unclear whether this DLPFC natural frequency slowing is present in early-course schizophrenia (EC-SCZ) and is associated with symptom severity and cognitive dysfunction. MethodsWe applied TMS–EEG to the left DLPFC in 30 individuals with EC-SCZ and 28 healthy control participants. Goal-directed working memory performance was assessed using the AX–Continuous Performance Task. The EEG frequency with the highest cumulative power at the stimulation site, or natural frequency, was extracted. We also calculated the local relative spectral power as the average power in each frequency band divided by the broadband power. ResultsCompared with the healthy control group, the EC-SCZ group had reduced DLPFC natural frequency (p = .0000002, Cohen’s d = −2.32) and higher DLPFC beta-range relative spectral power (p = .0003, Cohen’s d = 0.77). In the EC-SCZ group, the DLPFC natural frequency was inversely associated with negative symptoms. Across all participants, the beta band relative spectral power negatively correlated with AX–Continuous Performance Task performance. ConclusionsDLPFC oscillatory slowing is an early pathophysiological biomarker of schizophrenia that is associated with its symptom severity and cognitive impairments. Future work should assess whether noninvasive neurostimulation, including repetitive TMS, can ameliorate prefrontal oscillatory deficits and related clinical functions in patients with EC-SCZ.

Chalcogenide mid‐infrared 3 × 1 fiber combiner for highly efficient 2–5 µm power and wavelength combining

AbstractFiber combiner is an effective device to enhance the power level or broaden the spectral wavelengths through a single monolithic output aperture, by fusing multiple fibers together. This is particularly important in mid‐infrared (MIR) 2–5 µm range, in which the output power of a single laser is limited. Due to the high MIR transmission, chalcogenide glass is an ideal host for constructing MIR fiber combiner. In this study, we report the design, fabrication, and characterization of a homemade 3 × 1 chalcogenide glass fiber combiner. The fiber combiner includes a 3 × 1 As–S input fiber bundle and an output fiber. The input fiber bundle was made by tapering three As–S multimode fibers with a core diameter of 200 µm and a cladding diameter of 250 µm. The taper reduction ratio R was 2, and the length of the taper transition region was ∼2 cm. The output fiber with core diameter of 360 µm and cladding diameter of 570 µm was then spliced with the tapered end of the fiber bundle. The total length of the combiner was ∼53 cm. The measurement of power combination at 4.56 µm indicated that the transmission efficiency of three ports reached 80%, whereas the power combining efficiency of the combiner was measured to be ∼48%. In addition, efficient wavelength combining over one octave has been demonstrated, by launching three different lasers at 2.1, 3.39, and 4.56 µm through the 3 × 1 combiner. It proves that chalcogenide fiber combiner is promising for the applications of high‐level power combination and broadband wavelength combining in MIR 2–5 µm range.

Examining the types and purpose of cloud computing used for library services delivery in academic libraries in Kwara State, Nigeria

Background of the study: The implementation and integration of information and communication technology in library services and operations has revolutionized traditional practices, enabling libraries to adapt to the evolving needs of users in the digital era. Purpose: The main purpose of this study is to examine the types and purposes of cloud computing used for library service delivery in academic libraries in Kwara State, Nigeria. Methods: The study used a descriptive survey approach. The population was all the 108 librarians in the eight universities in Kwara State, Nigeria. A total enumeration sampling technique was employed, and a questionnaire was used to collect data from the librarians. The study answered three research questions. Findings: The study revealed that OCLC, Word cat, Google Docs, and other types of cloud computing are being utilized by the librarians. The study also revealed that poor internet connectivity, among other challenges, militates against the use of cloud computing for academic library service delivery. Conclusion: The study concluded that the librarians make use of cloud computing for library services. The study recommends that the library should provide reliable internet facilities with fast speeds, high broadband, and reliable power supplies, among others.

Preamble detection for broadband power line communication systems

Preamble detection for broadband power line communication systems

Feasibility of Stereo EEG Based Brain Computer Interfacing in An Adult and Pediatric Cohort.

Stereoelectroencephalography (sEEG) is a mesoscale intracranial monitoring method which records from the brain volumetrically with depth electrodes. Implementation of sEEG in BCI has not been well-described across a diverse patient cohort. Across eighteen subjects, channels with high frequency broadband (HFB, 65-115Hz) power increases during hand, tongue, or foot movements during a motor screening task were provided real-time feedback based on these HFB power changes to control a cursor on a screen. Seventeen subjects established successful control of the overt motor BCI, but only nine were able to control imagery BCI with ≥ 80% accuracy. In successful imagery BCI, HFB power in the two target conditions separated into distinct subpopulations, which appear to engage unique subnetworks of the motor cortex compared to cued movement or imagery alone. sEEG-based motor BCI utilizing overt movement and kinesthetic imagery is robust across patient ages and cortical regions with substantial differences in learning proficiency between real or imagined movement.