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This paper presents a novel approach for designing a reconfigurable and steerable antenna utilizing plasma dielectric slabs along the aperture of a pyramidal horn antenna. The antenna provides electronic control over the radiation gain and the direction of the main beam. The proposed configuration consists of four plasma slabs aligned perpendicular to the horn aperture along the horn axis, supplemented by four diagonally connected plasma slabs. Each plasma slab can be independently switched on or off, enabling dynamic adjustment of the radiation gain and steering of the main beam.Numerical investigations demonstrate that toggling the plasma slabs or controlling the plasma frequency allows precise control over the pyramidal horn antenna's radiation gain and beam steering. Selecting appropriate dimensions and angles for the plasma slabs is crucial in achieving the desired beam steering angle and radiation gain control. To validate the concept, the proposed antenna configuration is designed and numerically simulated at a frequency of 10 GHz. The results indicate that the radiation gain of the antenna can be significantly enhanced, reaching up to 6.5 dBi, and the main beam direction can be steered within a range of ±12°.This research presents a promising approach for achieving reconfigurability and beam steering capabilities in antenna systems by utilizing plasma dielectric slabs. The proposed design offers enhanced performance and flexibility, making it suitable for various applications in antenna technology. The ability to control beam steering and radiation gain without mechanical devices is essential in satellite and space communications. [ABSTRACT FROM AUTHOR]

Background The principle of gain control determines the efficiency of neuronal processing and can be enhanced with pharmacological or brain stimulation methods. It is a key factor for cognitive control, but the degree of how much gain control may be enhanced underlies a physical limit. Methods To investigate whether methylphenidate (MPH) and transcranial direct current stimulation (tDCS) share common underlying mechanisms and cognitive effects, we administered MPH and anodal tDCS (atDCS) over the right inferior frontal gyrus both separately and combined, while healthy adult participants (n = 104) performed a response selection and inhibition task. The recorded EEG data were analyzed with a focus on theta band activity, and source estimation analyses were conducted. Results The behavioral data show that MPH and atDCS revealed interactive effects on the ability to inhibit responses. Both MPH and atDCS modulated task-related theta oscillations in the supplementary motor area when applied separately, making a common underlying mechanism likely. When both stimulation methods were combined, there was no doubling of effects in the supplementary motor area but a shift to inferior frontal areas in the cortical network responsible for theta-driven processing. Conclusions The results indicate that both MPH and atDCS likely share a common underlying neuronal mechanism, and interestingly, they demonstrate interactive effects when combined, which are most likely due to the physical limitations of gain control increases. The current study provides critical groundwork for future combined applications of MPH and non-invasive brain stimulation. [ABSTRACT FROM AUTHOR]

Primates rely on two eyes to perceive depth, while maintaining stable vision when either one eye or both eyes are open. Although psychophysical and modeling studies have investigated how monocular signals are combined to form binocular vision, the underlying neuronal mechanisms, particularly in V1 where most neurons exhibit binocularity with varying eye preferences, remain poorly understood. Here, we used two-photon calcium imaging to compare the monocular and binocular responses of thousands of simultaneously recorded V1 superficial-layer neurons in three awake macaques. During monocular stimulation, neurons preferring the stimulated eye exhibited significantly stronger responses compared to those preferring both eyes. However, during binocular stimulation, the responses of neurons preferring either eye were suppressed on the average, while those preferring both eyes were enhanced, resulting in similar neuronal responses irrespective of their eye preferences, and an overall response level similar to that with monocular viewing. A neuronally realistic model of binocular combination, which incorporates ocular dominance-dependent divisive interocular inhibition and binocular summation, is proposed to account for these findings.

Divisive normalization is a model of canonical computation of brain circuits. We demonstrate that two cascaded divisive normalization processors (DNPs), carrying out intensity/contrast gain control and elementary motion detection, respectively, can model the robust motion detection realized by the early visual system of the fruit fly. We first introduce a model of elementary motion detection and rewrite its underlying phase-based motion detection algorithm as a feedforward divisive normalization processor. We then cascade the DNP modeling the photoreceptor/amacrine cell layer with the motion detection DNP. We extensively evaluate the DNP for motion detection in dynamic environments where light intensity varies by orders of magnitude. The results are compared to other bio-inspired motion detectors as well as state-of-the-art optic flow algorithms under natural conditions. Our results demonstrate the potential of DNPs as canonical building blocks modeling the analog processing of early visual systems. The model highlights analog processing for accurately detecting visual motion, in both vertebrates and invertebrates. The results presented here shed new light on employing DNP-based algorithms in computer vision. [ABSTRACT FROM AUTHOR]

Gain-control mechanisms adjust neuronal responses to accommodate the wide range of stimulus conditions in the natural environment. Contrast gain control and extraclassical surround suppression are two manifestations of gain control that govern the responses of neurons in the early visual system. Understanding how these two forms of gain control interact has important implications for the detection and discrimination of stimuli across a range of contrast conditions. Here, we report that stimulus contrast affects spatial integration in the lateral geniculate nucleus of alert macaque monkeys (male and female), whereby neurons exhibit a reduction in the strength of extraclassical surround suppression and an expansion in the preferred stimulus size with low-contrast stimuli compared with high-contrast stimuli. Effects were greater for magnocellular neurons than for parvocellular neurons, indicating stream-specific interactions between stimulus contrast and stimulus size. Within the magnocellular pathway, contrast-dependent effects were comparable for ON-center and OFF-center neurons, despite ON neurons having larger receptive fields, less pronounced surround suppression, and more pronounced contrast gain control than OFF neurons. Together, these findings suggest that the parallel streams delivering visual information from retina to primary visual cortex, serve not only to broaden the range of signals delivered to cortex, but also to provide a substrate for differential interactions between stimulus contrast and stimulus size that may serve to improve stimulus detection and stimulus discrimination under pathway-specific lower and higher contrast conditions, respectively.SIGNIFICANCE STATEMENT Stimulus contrast is a salient feature of visual scenes. Here we examine the influence of stimulus contrast on spatial integration in the lateral geniculate nucleus (LGN). Our results demonstrate that increases in contrast generally increase extraclassical suppression and decrease the size of optimal stimuli, indicating a reduction in the extent of visual space from which LGN neurons integrate signals. Differences between magnocellular and parvocellular neurons are noteworthy and further demonstrate that the feedforward parallel pathways to cortex increase the range of information conveyed for downstream cortical processing, a range broadened by diversity in the ON and OFF pathways. These results have important implications for more complex visual processing that underly the detection and discrimination of stimuli under varying natural conditions.

Animals' sensory systems adjust their responsiveness to environmental stimuli that vary greatly in their intensity. Here we report the neural mechanism of experience-dependent sensory adjustment, especially gain control, in the ASH nociceptive neurons in Caenorhabditis elegans. Using calcium imaging under gradual changes in stimulus intensity, we find that the ASH neurons of naive animals respond to concentration increases in a repulsive odor 2-nonanone regardless of the magnitude of the concentration increase. However, after preexposure to the odor, the ASH neurons exhibit significantly weak responses to a small gradual increase in odor concentration while their responses to a large gradual increase remain strong. Thus, preexposure changes the slope of stimulus–response relationships (i.e. , gain control). Behavioral analysis suggests that this gain control contributes to the preexposure-dependent enhancement of odor avoidance behavior. Mathematical analysis reveals that the ASH response consists of fast and slow components, and that the fast component is specifically suppressed by preexposure for the gain control. In addition, genetic analysis suggests that G protein signaling may be required for the regulation of fast component. We propose how prior experience dynamically and specifically modulates stimulus–response relationships in sensory neurons, eventually leading to adaptive modulation of behavior. [ABSTRACT FROM AUTHOR]

A novel ultra-wideband low-noise amplifier realized by a dual-resonance load network and a Cascode stage with bandwidth tuning capability is presented in this paper. Impedance matching at the input port is accomplished by a front end common gate stage along with a dual-resonance network. Ultra-wide bandwidth, consistent high-power gain and constant low noise figure throughout the desired frequency band is achieved due to the smart configuration of the proposed topology. Bandwidth tuning is obtained utilizing an analog voltage-controlled MOS Varactor. The proposed amplifier performance is verified by both 180 nm CMOS Technology post-layout simulations at Cadence Spectre Software and also measurement results which fortunately exhibit a good matching with each other. These analyses provide 14.5 ± 1 dB power gain, 3.8 ± 0.2 dB noise figure, and input impedance matching less than 10.8 dB. Meanwhile, the reverse isolation and output impedance matching is achieved at frequency band of 3–12 GHz to be − 76 dB and − 14 dB, respectively. The structure has a low-power consumption of 23mW. [ABSTRACT FROM AUTHOR]

It has been suggested that there may be an imbalance of excitation and inhibitory processes in the visual areas of the brain in people with migraine aura (MA). One idea is thalamocortical dysrhythmia, characterized by disordered oscillations, and thus disordered communication between the lateral geniculate nucleus and the cortex. Cross-orientation suppression is a visual task thought to rely on inhibitory processing, possibly originating in the lateral geniculate nucleus. We measured both resting-state oscillations and cross-orientation suppression using EEG over occipital areas in people with MA and healthy volunteers. We found evidence of cross-orientation suppression in the SSVEP responses, but no evidence of any group difference. Therefore, inhibitory processes related to cross-orientation suppression do not appear to be impaired in MA.

• We find a novel bidirectional size adaptation aftereffect, clear in demonstrations. • Perceived reductions in size are around twice as large as perceived increases. • Not explained by perceived contour displacement and/or shifts in spatial frequency. • The aftereffect does not depend on the relative adaptor and target orientations. • A contrast perception model with a new form of population coding fits the results. In previous psychophysical work we found that luminance contrast is integrated over retinal area subject to contrast gain control. If different mechanisms perform this operation for a range of superimposed retinal regions of different sizes, this could provide the basis for size-coding. To test this idea we included two novel features in a standard adaptation paradigm to discount more pedestrian accounts of repulsive size-aftereffects. First, we used spatially jittering luminance-contrast adaptors to avoid simple contour displacement aftereffects. Second, we decoupled adaptor and target spatial frequency to avoid the well-known spatial frequency shift aftereffect. Empirical results indicated strong evidence of a bidirectional size adaptation aftereffect. We show that the textbook population model is inappropriate for our results, and develop our existing model of contrast perception to include multiple size mechanisms with divisive surround-suppression from the largest mechanism. For a given stimulus patch, this delivers a blurred step-function of responses across the population, with contrast and size encoded by the height and lateral position of the step. Unlike for textbook population coding schemes, our human results (N = 4 male, N = 4 female) displayed two asymmetries: (i) size aftereffects were greatest for targets smaller than the adaptor, and (ii) on that side of the function, results did not return to baseline, even when targets were 25% of adaptor diameter. Our results and emergent model properties provide evidence for a novel dimension of visual coding (size) and a novel strategy for that coding, consistent with previous results on contrast detection and discrimination for various stimulus sizes. [ABSTRACT FROM AUTHOR]

Purpose: The neurotransmitter serotonin has a strong effect on behaviour and motor control. Regarding motor control, serotonin contributes to the development of fatigue and is also involved in the ability of motor neurones to operate across a large range of forces (gain control). The consumption of tryptophan-rich supplements (such as α-lactalbumin) is of interest because this amino acid is the only precursor for brain serotonin synthesis. Therefore, the purpose of this study was to determine the effects of α-lactalbumin supplementation on neuromuscular performance. Methods: Using a randomised double-blind cross-over design, 16 healthy participants performed plantar flexor and handgrip maximal voluntary contractions, a 30-s submaximal handgrip contraction, and a plantar flexor fatigue protocol before and 90 min after consuming either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (corn-starch). Sleepiness, mood, and cognition were assessed to evaluate any psychological effects. Results: α-Lactalbumin decreased force steadiness by 25% during the sustained submaximal handgrip contraction (p < 0.01) and induced greater fatigue (15% reduction in total torque–time integral, p = 0.01) during the fatigue protocol. These effects were not observed for the other control beverages. No effects were found for maximal or explosive strength, or psychological measurements. Conclusions: 40 g of α-lactalbumin increased handgrip force variability and reduced performance during fatiguing muscle contractions but did not influence brief maximal contractions or psychological parameters in healthy individuals. These findings support the hypothesis that the consumption of α-lactalbumin can increase motor neurone input–output gain and exacerbate central fatigue during sustained maximal exercise. [ABSTRACT FROM AUTHOR]

A simple yet effective approach for programmable gain amplifier (PGA) with a high precision decibel (dB)-linear characteristic and wide bandwidth is presented in this brief. This novel approach is presented by innovatively combining two techniques. Based on the binary-weighted switching technique, the circuit can approach an accurate pseudo-exponential function without using an additional exponential generator for gain control. By adopting the active feedback circuit structure, the bandwidth of PGA can be extended and it also contributes to improve the robustness, both of which cleverly reached a good consistency. The proposed PGA is fabricated in a $0.18~{\mu }\text{m}$ CMOS technology, the core circuit occupies an area of 0.11 mm2. Operated at a supply voltage of 1.8 V, the PGA consumes 8.21 mW. The measurement results show that the voltage gain of the proposed PGA can be controlled from −4.2 dB to 25.9 dB with a gain error less than ±0.09 dB, and the minimum −3dB bandwidth is almost 630 MHz. The input 1dB compression point is measured from −28.7 to 0.5 dBm, while the input referred noise is from 22.4 to 70.9 nV/ ${{\sqrt {}}}$ Hz. [ABSTRACT FROM AUTHOR]

The foremost method to exhaust heat sourced from electronic devices is to use heat sinks. However, in practice, these structures behave as actual antennas and cause interference problems. The selected heat sink like many others is performing like a real antenna whose gain at 4.9 GHz is ~ 7 dBi both in simulation and measurement. In this study, a novel gain (radiation pattern) controlling belt made up of a metamaterial (MTM) structure was designed and dressed to the heat-sink antenna. The effect of the position of the belt on the antenna pattern is investigated. The sliding position of the belt which allows for dynamic gain control varies the antenna gain between 3.38 and 7.36 dBi (~ 7 dB in ${\theta }$ angle and ~ 9 dB in ${\emptyset }$ angle). Maximum gain enhancement reaches up to 18.43 dB and maximum suppression ratio reaches up to 21.36 dB for the entire angle. [ABSTRACT FROM AUTHOR]

This letter presents a 39-GHz phase-inverting variable gain power amplifier (VGPA) for 5G communication. Adopting a Gilbert structure-based variable gain amplifier (VGA) stage, the VGPA realized the dB-linear gain control characteristic as well as 180° phase inversion. At 0°/180° phase states, the 39-GHz VGPA achieves the maximum gain of 38.7/38.9 dB with gain tuning range of 5.6/5.2 dB, respectively. Over 38–43 GHz, the phase inversion error is limited within 5.9°, and the rms phase error is less than 3.6°/2.2°. Meanwhile, with the metal interleaving coplanar transformer matching network, this VGPA achieves 17.7/17.6-dBm Psat and 13.2/13.36-dBm OP1 dB, with the power added efficiency (PAE) of 35%/34.5% and 13.6%/14.4% at the saturation and 1-dB compression points, respectively. Over the gain control states, the OP1 dB fluctuation is less than 0.3 dB. Implemented in a 65-nm CMOS process, the proposed VGPA consumes 150 mW with a chip area of 0.3 mm2. [ABSTRACT FROM AUTHOR]

A 28 GHz dual-mode phase-invariant wide-dynamic-range variable-gain amplifier (VGA) with adaptive phase compensators is presented for use as a gain control element in a beamforming IC, which must have a small chip size and low power consumption. It consists of a single-stage differential amplifier with main and auxiliary signal paths, where the auxiliary paths are introduced to achieve most-significant-bit (MSB) gain control. The wide-gain dynamic range is also covered through a least-significant-bit (LSB) gain-control scheme, which is implemented with bias control of common gate (CG) transistors in the main signal paths. In addition, the phase variations due to the gain controls are drastically reduced by introducing phase compensators for both gain controls. The proposed VGA shows a gain dynamic range of 24 dB, maximum gain of 13 dB and root-mean-square (RMS) phase error of 2.77 degrees at 28 GHz. The maximum DC power consumption is 24 mW at the maximum gain, the minimum is 4 mW at the minimum gain, and the chip size is 0.066 mm2. [ABSTRACT FROM AUTHOR]

This article presents a neural-recording IC with automatic gain control (AGC) according to the input signal level. AGC enhances the dynamic range (DR) of the recording IC by more than 30 dB and allows it to take the benefits of the front-end amplification-based and direct-conversion-based recording structures concurrently. By adaptively controlling the analog front-end (AFE) gain, the input-referred noise (IRN) of the overall system is greatly reduced while ensuring a wide DR. A continuous-time (CT) dynamic-zoom $\Delta \Sigma $ ADC (CT-Zoom-ADC) is used for power-efficient two-step conversion. The coarse conversion output is reused for AGC, and the fine conversion resolution is adjusted adaptively by modifying the oversampling ratio according to the varying AFE gain. The presented neural-recording IC achieves 99.5-dB DR and 6.1- $\mu \text{V}_{\textrm {rms}}$ IRN over 5-kHz bandwidth, resulting in FoMDR of 185.2 dB, the effective number of bits (ENOB) of 11.4 bits, and tolerance against artifacts with differential voltage amplitudes up to 1.6 $\text{V}_{\text {pp}}$. Measurements with pulsatile artifacts and experiments in vivo validate that the proposed IC is applicable to the closed-loop neural interface. [ABSTRACT FROM AUTHOR]

A comprehensive analysis is derived to understand the mechanism of phase errors in cascode CMOS variable gain amplifiers (VGAs). According to the analysis, source–drain parasitic capacitors ($C_{\mathrm {ds}}$) of common gate (CG) transistors in off-region are the main causes for phase errors. An independent cascode current canceling (ICCC) VGA is proposed to relax phase errors by minimizing the effect of $C_{\mathrm {ds}}$ within a broadband. The proposed VGA achieves a 16-dB gain control with a 1.6° phase error and a 0.2-dB gain error from 15 to 25 GHz by 40-nm CMOS technology. Owing to the cascode structure, the peak gain of the VGA is 12 dB with only one stage including input–output pads consuming 16-mW power from 1.1-V voltage. Besides, the VGA can also serve as a 180° phase shifter (PS) due to ICCC structure with a 1.5° phase error and a 0.2-dB gain error from 15 to 25 GHz. The measured −3-dB bandwidth is 5 GHz, and output 1-dB compression point (OP1dB) is over 2.5 dBm in the maximum gain state. The core area is 0.065 mm2 excluding input–output pads. [ABSTRACT FROM AUTHOR]

The striatum is a subcortical brain region responsible for the initiation and termination of voluntary movements. Striatal spiny projection neurons receive major excitatory synaptic input from neocortex and thalamus, and cyclic nucleotides have long been known to play important roles in striatal function. Yet, the precise mechanism of action is unclear. Here, we combine optogenetic stimulation, 2‐photon imaging, and genetically encoded scavengers to dissect the regulation of striatal synapses in mice. Our data show that excitatory striatal inputs are tonically depressed by phosphodiesterases (PDEs), in particular PDE1. Blocking PDE activity boosts presynaptic calcium entry and glutamate release, leading to strongly increased synaptic transmission. Although PDE1 degrades both cAMP and cGMP, we uncover that the concentration of cGMP, not cAMP, controls the gain of striatal inputs. Disturbing this gain control mechanism in vivo impairs motor skill learning in mice. The tight dependence of striatal excitatory synapses on PDE1 and cGMP offers a new perspective on the molecular mechanisms regulating striatal activity. Synopsis: The strength of striatal input synapses is controlled by the activity of phosphodiesterases and cGMP. Disturbing this gain control mechanism in corticostriatal synapses impairs motor learning in mice. Inhibiting phosphodiesterases boosts transmission at cortico‐ and thalamostriatal synapses.This effect is mediated by presynaptic cGMP‐ and not cAMP‐signaling.Disrupting presynaptic cGMP in corticostriatal synapses impairs motor learning on the rotarod. [ABSTRACT FROM AUTHOR]

This paper presents a digital processing system for terrestrial laser range finding systems. It is mainly comprised of a commercial digital signal processor with 400 MHz. For the signal digitization, an analog-to-digital converter with a 12-bit resolution is sampled with 50 MS/s. Such a digital system architecture has several advantages: automatic gain control, coherent multi-pulse averaging, digital signal filtering, upsampling, and advanced peak detection methods. When combined with a suitable laser and detector unit, the digital system outperforms the classic analog threshold-based laser finders with regard to required laser output power, multitarget discrimination, and peak detection accuracy. The best results were achieved using a matched filter, compared to wavelet denoising techniques and classic Savitzky-Golay filtering. Finally, this system architecture allows for a small-sized, lightweight, battery-operated, and energy-efficient, class 1 eye-safe laser range finder, capable of measuring distances up to multiple km with accuracy and precision of better than 1 m to uncooperative targets. [ABSTRACT FROM AUTHOR]

Total Harmonic Distortion (THD) is an important index to measure the nonlinear degree of channel. The automatic measurement device applied in arbitrary output waveform identification and total harmonic distortion of the audio small signal amplification system has become an effective means to detect the signal amplification performance. In order to accurately calculate the total harmonic distortion of the amplified waveform, FFT technique is adopted. In order to improve the system efficiency, high frequency sampling and half extraction techniques are adopted. Dynamic control relays, resistance-capacitance components and multi-stage amplification are used to reasonably adjust the position of the static operating point of the amplification system and the size of the input waveform to realize the output of different types of distorted waveforms. Based on microcontroller stm32f103c6, the combination switch completes the collection, identification, calculation and display of arbitrary waveform in one-button, greatly improving the working efficiency of small signal amplification systems. Matlab algorithm simulation, Multisim circuit simulation and practical test show that, the automatic calculation device of arbitrary waveform THD for small signal amplification systems consisting of multi-stage transistor amplification consistency adjustment circuit and microcontroller FFT operations can accurately and real-time identify waveforms and calculate THD. The one-button switching design is convenient to operate, saves cost, and has practical value. [ABSTRACT FROM AUTHOR]

In this brief, we present a 28 GHz high slope automatic switching power detector system using a PMOS current-steering VGA and Schmitt trigger (ST) for 5G mobile communication. The forward RF path is composed of a four-stages variable gain amplifier and a buffer amplifier. The feedback path is composed of the power detector, two STs, and an inverter to achieve an automatic gain switching mechanism. The input RF small-signal is amplified by the RF path and converted to dc voltage by power detector. By feedback path to switch to different gain states, it can extend the overall dynamic range with high slope and avoid the system from saturation. Based on ±1 dB log error, the measured minimum detectable power and dynamic range are −47.2 dBm and 41.5 dB at 28 GHz. The peak slope value are 61/59/67 mV/dB under three modes. Total dc power consumption is only 35 mW for 1.8 V supplied voltage. To our best knowledge, this power detector system is the first time using the automatic switching technique in the millimeter-wave band power detector. It has better minimum detectable power, dynamic range, and the highest slope among published power detector systems. [ABSTRACT FROM AUTHOR]

Automatic speech recognition (ASR) is an essential technique of human–computer interactions; gain control is a commonly used operation in ASR. However, inappropriate gain control strategies can lead to an increase in the word error rate (WER) of ASR. As there is a current lack of sufficient theoretical analyses and proof of the relationship between gain control and WER, various unconstrained gain control strategies have been adopted on realistic ASR systems, and the optimal gain control with respect to the lowest WER, is rarely achieved. A gain control strategy named maximized original signal transmission (MOST) is proposed in this study to minimize the adverse impact of gain control on ASR systems. First, by modeling the gain control strategy, the quantitative relationship between the gain control strategy and the ASR performance was established using the noise figure index. Second, through an analysis of the quantitative relationship, an optimal MOST gain control strategy with minimal performance degradation was theoretically deduced. Finally, comprehensive comparative experiments on a Mandarin dataset show that the proposed MOST gain control strategy can significantly reduce the WER of the experimental ASR system, with a 10% mean absolute WER reduction at −9 dB gain. [ABSTRACT FROM AUTHOR]

Listening in noisy or complex sound environments is difficult for individuals with normal hearing and can be a debilitating impairment for those with hearing loss. Extracting meaningful information from a complex acoustic environment requires the ability to accurately encode specific sound features under highly variable listening conditions and segregate distinct sound streams from multiple overlapping sources. The auditory system employs a variety of mechanisms to achieve this auditory scene analysis. First, neurons across levels of the auditory system exhibit compensatory adaptations to their gain and dynamic range in response to prevailing sound stimulus statistics in the environment. These adaptations allow for robust representations of sound features that are to a large degree invariant to the level of background noise. Second, listeners can selectively attend to a desired sound target in an environment with multiple sound sources. This selective auditory attention is another form of sensory gain control, enhancing the representation of an attended sound source while suppressing responses to unattended sounds. This review will examine both "bottom-up" gain alterations in response to changes in environmental sound statistics as well as "top-down" mechanisms that allow for selective extraction of specific sound features in a complex auditory scene. Finally, we will discuss how hearing loss interacts with these gain control mechanisms, and the adaptive and/or maladaptive perceptual consequences of this plasticity. [ABSTRACT FROM AUTHOR]

A 60-GHz variable-gain active phase shifter using particular-sized digital-RF cells is proposed, which is fabricated using a 65-nm CMOS process. The phase shifter consists of an input buffer, an $I/Q$ generator, and vector-summing amplifiers with digital-RF cells. In a vector-sum phase shifter using a conventional tail current steering scheme, the operation regions of vector-summing amplifiers are changed with phase and gain states. Accordingly, their input impedances are altered significantly, which causes gain and phase imbalances of the $I/Q$ generator, especially around 0°, 90°, 180°, and 270°. This makes the rms phase and gain errors of the phase shifter increase. In this article, a vector-summing amplifier that always has a constant input impedance in all phases and gain states is proposed. A circular constellation and a dynamic range of more than 15 dB are implemented by using particular-sized digital-RF cells. The proposed phase shifter shows the rms gain and phase errors of < 0.29 dB and <2.01°, respectively, in a 10-GHz bandwidth of 55–65 GHz with 3-bit gain and 4-bit phase resolutions. The chip area and power consumption are 0.38 mm2 and 25.2 mW, respectively. [ABSTRACT FROM AUTHOR]

A Ka-band differential variable gain amplifier (VGA) applying symmetrical unit arrays with 6-bit digital-controlled is presented. The proposed VGA, based on the conventional current steering theory, uses symmetrical unit arrays that keep the output impedance constant, while digital-controlled voltage changes. Then it combines neutralizing capacitances to counteract the Miller effect of parasitic capacitances between gain and drain of input transistors. The VGA with symmetrical unit arrays ensures the consistency of phase variation during gain fluctuation. The VGA is fabricated in a 65-nm CMOS technology, and achieves −20.2 to −4.2 dB gain varied with 1.52 dBm IP1dB as well as 8.6 dB noise figure at 36 GHz and less than 4.9° phase variation, while consuming 15.6 mW across 30.5–39 GHz frequency range. [ABSTRACT FROM AUTHOR]

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This brief proposes a variable gain power amplifier (VG-PA) with stable linearity for n257/n258 frequency band applications. A switched-capacitor array is proposed in the cascode (CC) circuit to control the gain while maintaining linearity. A compensation inductor is introduced between the common-emitter (CE) and common-base (CB) transistors to suppress the phase variation. For the proof of concept, the VG-PA was fabricated in a 0.13- $\mu \text{m}$ SiGe BiCMOS technology with a core size of 0.59 $\times $ 0.46 mm2. Measurements show that at 24/26/28/29.5 GHz, over 5.7/5.5/7.0/7.5-dB gain tuning range, the output 1-dB compression point (OP1dB) is better than 14 dBm with $ {\Delta }$ OP1dB less than 1.2 dB, the third-order output intercept point (OIP3) is better than 22 dBm with $ {\Delta }$ OIP3 less than 3.4 dB, and the phase variation ($ {\Delta }{\varphi }$) is from 3 to 9.5°. To the author’s best knowledge, this work has the lowest linearity variation among Si-based variable gain amplifiers at millimeter-wave frequency band. [ABSTRACT FROM AUTHOR]

This brief presents a compact variable gain amplifier (VGA) with continuous time-gain compensation (TGC) for ultrasound imaging. The proposed VGA utilizes an open-loop topology and transconductance-subtraction load for compact implementation with sufficient gain range. To compensate for gain nonlinearity of VGA, this work proposes a systematic predistortion of gain-control signal to enhance an accuracy of TGC operation. The proposed VGA implemented in 180-nm CMOS process occupies 0.025 mm2, and consumes 0.96 mW for the maximum gain condition with a supply voltage of 1.8 V. A real-time continuous TGC has been illustrated in measurement. The fabricated VGA achieves a gain range of 37 dB, a gain error below 1.4 dB, and an input referred noise of 8.6 nV/ ${\surd }$ Hz for the maximum gain condition. [ABSTRACT FROM AUTHOR]

This article presents a 23–28-GHz digital-controlled phase-invariant and ultralow gain error variable gain amplifier (VGA) for 5G applications. The mechanisms of gain control and phase variation in CMOS VGA based on single-level transistor structure are analyzed in detail. According to the analysis, an active cross-coupling neutralization (ACCN) technique is proposed. The ACCN technique not only compensates for phase variation, but also makes phase compensation insensitive to the process, supply voltage, and temperature (PVT) variations. For achieving ultralow gain error, an asymmetric capacitive gain resolution improvement (ACGRI) technique is adopted, which realizes a fine gain step with low control circuit complexity. Further to reduce gain error, greatly improving the accuracy and robustness against PVT of gain control is necessary. With regard to this, a current-type digital-to-analog converter (DAC) is also integrated onto the chip. The proposed VGA is demonstrated in 65-nm CMOS technology with a core chip area of 0.14 mm2. Under 5-b digital gain control conditions, the presented VGA achieves a measured linear gain tunability range of 6.2 dB with a 0.2-dB fine tuning step. The measured root mean square (rms) phase error is less than 0.92° across 24–28 GHz with a minimum value of 0.63° at 27.8 GHz. The rms gain error is less than 0.13 dB, with a minimum value of only 0.03 dB at 25 GHz. At the maximum gain state, the proposed CS VGA exhibits a peak gain of 29.4 dB with 3-dB bandwidth of 23.5–27.5 GHz and the minimum noise figure is 4.8 dB at 26 GHz. Besides, the measured OP1dB and OP3dB are 6.3 and 9.6 dBm, respectively. The influence of VT variations on the phase compensation and gain tuning is also measured, and the proposed VGA exhibits strong robustness. [ABSTRACT FROM AUTHOR]

This letter presents a high precision wideband active vector-modulating phase shifter with high dynamic range gain control ability. Compared with conventional switching-filter phase shifter and vector-modulation phase shifter, this $\Delta $ – $\Sigma $ modulated vector phase shifter can provide quasi-continuous phase and gain control capability. According to the experimental results, the dynamic range of gain control is greater than 35.5 dB. The output reflection is lower than −10 dB through the 18–50-GHz band, and the input reflection is lower than −10 dB from 18 to 45 GHz. The phase shifter occupies 700 $\mu \text{m}\,\,\times $ 900 $\mu \text{m}$ on 0.13- $\mu \text{m}$ SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology, and the core size is only $400\,\,\mu \text{m}\,\,\times 500\,\,\mu \text{m}$. After digital calibration, the proposed phase shifter has achieved the highest phase and gain control precision compared with the state-of-the-art digital controlled phase shifters. [ABSTRACT FROM AUTHOR]

In this paper, a calibration approach based on transfer function extraction for the Cartesian vector modulator (VM) is presented. Three kinds of VM models-the ideal VM model, the frequency-dependent VM model and the modified frequency-dependent VM model, are introduced in the proposed calibration approach. The calibration approach starts with an initialization of the transfer function of the modified frequency-dependent VM model. Then, the parameters of the transfer function are modified and extracted from the data of the measured transmission state (transmission amplitude and phase) of the actual VM by iteration, until the transmission state predicted by the extracted transfer function agrees well with the measured transmission state. Subsequently, the extracted transfer function of the modified frequency-dependent VM model is capable of describing the transmission characteristics of the actual VM, and the calibrated baseband control voltages for the desired transmission amplitude and phase of the actual VM are able to be obtained by using the extracted transfer function. An actual VM is used as an example to verify this method. By adopting the proposed method, the maximum amplitude and phase errors at different complex gain setpoints are reduced to 0.05 dB and 0.3° respectively after only two iteration steps. Since the actual VM is able to be accurately calibrated in only a few iteration steps, the results reveal that high accuracy and efficiency can be obtained in this calibration technique, which is well suited for applications involving high-accuracy calibration, real-time calibration and multichannel VM system calibration.

With the development of fast digitiser and digital signal processing techniques, wide-band digital radio-over-fiber (DRoF) based wireless fronthaul systems have been extensively studied as a way of offering multi-service wireless coverage. With data compression, the high digital data rate caused by digitisation can be reduced so as to minimise the infrastructure cost for last-mile cellular coverage. However, data compression always comes with the cost of a lower input power dynamic range. To overcome the issue, this paper proposes a novel fast-settling two-stage automatic gain control (FSS-AGC) algorithm, in which gain adjustment is carried out by a multi-threshold decision mechanism with a fast-settling time (within $2~\mu $ s), high stability and great accuracy. By introducing a novel gain control mechanism which simultaneously adjusts the gain in the digital and RF domains, the loss of dynamic range after compression is compensated. This algorithm is applied and demonstrated in a DRoF based digital distributed antenna system (DDAS) which supports all current cellular services from 3 Chinese mobile network operators (MNOs). The demonstration shows over 73dB dynamic range, with 40dB improvement compared with conventional links. Its promising properties and excellent performance enable its potential application in next-generation converged networks for Internet of things (IoT) and 5G services.

Listening in noisy or complex sound environments is difficult for individuals with normal hearing and can be a debilitating impairment for those with hearing loss. Extracting meaningful information from a complex acoustic environment requires the ability to accurately encode specific sound features under highly variable listening conditions and segregate distinct sound streams from multiple overlapping sources. The auditory system employs a variety of mechanisms to achieve this auditory scene analysis. First, neurons across levels of the auditory system exhibit compensatory adaptations to their gain and dynamic range in response to prevailing sound stimulus statistics in the environment. These adaptations allow for robust representations of sound features that are to a large degree invariant to the level of background noise. Second, listeners can selectively attend to a desired sound target in an environment with multiple sound sources. This selective auditory attention is another form of sensory gain control, enhancing the representation of an attended sound source while suppressing responses to unattended sounds. This review will examine both “bottom-up” gain alterations in response to changes in environmental sound statistics as well as “top-down” mechanisms that allow for selective extraction of specific sound features in a complex auditory scene. Finally, we will discuss how hearing loss interacts with these gain control mechanisms, and the adaptive and/or maladaptive perceptual consequences of this plasticity.

Background and Hypothesis: The human visual system streamlines visual processing by suppressing responses to textures that are similar to their surrounding context. Surround suppression is weaker in individuals with schizophrenia (ISZ); this altered use of visuospatial context may relate to the characteristic visual distortions they experience., Study Design: To understand atypical surround suppression in psychotic psychopathology, we investigated neurophysiological responses in ISZ, healthy controls (HC), individuals with bipolar disorder (IBP), and first-degree relatives (ISZR/IBPR). Participants performed a contrast judgment task on a circular target with annular surrounds, with concurrent electroencephalography. Orientation-independent (untuned) suppression was estimated from responses to central targets with orthogonal surrounds; the orientation-dependence of suppression was estimated by fitting an exponential function to the increase in suppression as surrounds became more aligned with the center., Results: ISZ exhibited weakened untuned suppression coupled with enhanced orientation-dependence of suppression. The N1 visual evoked potential was associated with the orientation-dependence of suppression, with ISZ and ISZR (but not IBP or IBPR) showing enhanced orientation-dependence of the N1. Collapsed across orientation conditions, the N1 for ISZ lacked asymmetry toward the right hemisphere; this reduction in N1 asymmetry was associated with reduced untuned suppression, real-world perceptual anomalies, and psychotic psychopathology. The overall amplitude of the N1 was reduced in ISZ and IBP., Conclusions: Key measures of symptomatology for ISZ are associated with reductions in untuned suppression. Increased sensitivity for ISZ to the relative orientation of suppressive surrounds is reflected in the N1 VEP, which is commonly associated with higher-level visual functions such as allocation of spatial attention or scene segmentation., (Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center 2024.)

This article presents a $4 \times 10$ Gb/s low-noise adaptive optical receiver, utilizing a current-reuse architecture and channel crosstalk-remove techniques in 65-nm CMOS process. The receiver integrates a transimpedance amplifier (TIA), a continuous-time linear equalizer (EQ), high-gain and high-bandwidth limiting amplifiers, and a 50- $\Omega $ output driver into a single die. The TIA employs a common-source-based pseudo-differential topology with input series inductive peaking and $g_{m}$ -enhancement to improve bandwidth and noise performance. An automatic-gain-control loop scheme is presented which solves the bandwidth variation issue caused by variation of the TIA input impedance, across a large dynamic range of a small input to a maximum overload current. Multiple crosstalk reduction techniques are adopted to improve the channel isolation performance. The 850-nm vertical cavity surface emitting laser (VCSEL)-based full-link measurement results show that the optical receiver achieves $20.4~\mu \text{A}_{\mathrm {pp}}$ sensitivity bit-error-rate (BER $ < 1\text{e}$ -12) with a 200-fF photodiode, competitive with other prior CMOS-based TIAs. The crosstalk over different channels is also measured, demonstrating only a sensitivity penalty of 1 dB. [ABSTRACT FROM AUTHOR]

Studies on Kenyon Cells (KCs) in the olfactory system of locust have found evidence that some of them are more responsive towards stimuli than others. This variability suggests that there could be a heterogeneous neural threshold distribution among KCs. This work explores the hypothesis that the heterogeneity in neural thresholds could control the activity level of populations of neurons and facilitate the generation of sparse code to achieve a better representation of stimuli. In order to study this hypothesis, an artificial neural network that adapts many of the strategies observed in the locust olfactory system is proposed, including a new learning algorithm capable of finding the best neural threshold distribution to resolve a certain classification problem and a gain control term that keeps the activity level of the neurons in the hidden layer under a certain limit. The bio-inspired neural network gets the best results when the activity level in the hidden layer is low, for which neural thresholds are more important for a better performance than the connections between the neurons in different layers. Also, it was found that the separability of the internal representations of the different patterns in the classification problem improves when the thresholds are adjusted by the learning algorithm in order to control the activity level. Finally, the performance of this network was compared to SVMs and MLP when applied to resolve a complex classification task with data collected by electronic noses and affected by sensor drift, for which the bio-inspired network obtains very satisfactory results, reaching a performance similar or even better than SVMs and MLP. [ABSTRACT FROM AUTHOR]

Gain amplitude modulation multichannel ASIC (GAMMA) is a 16-channel application specified integrated circuit (ASIC), designed in 0.35- $\mu \text{m}$ technology to read the charge provided by silicon photomultipliers (SiPMs) on a wide amplitude range. This chip was designed to satisfy the demanding requirements of the INFN the GAMMA project, where a 3” $\times3$ ” large lanthanum bromide crystal is to be read by SiPMs, aiming at state-of-the-art energy resolution. Because the energy range of the application is 100 keV–20 MeV, signals in a wide dynamic range (DR) have to be processed by the ASIC. This wide DR requirement raised the necessity of an adaptive gain change solution in order to guarantee a high signal-to-noise ratio together with a large full-scale range. While the ASIC input stage features a programmable static gain, the analog filtering channel exploits a self-triggered gated integrator stage with an automatically adjusted gain for each detected input current pulse; one of the following values is selected: 10, 2, or 0.83 [mV/pC]. The gated integrator gain is predictively adjusted before the circuit reaches saturation due to a time-gated threshold mechanism and provides negligible charge loss when the gain is switched (< 20 fC). A preintegration feature is also implemented in order to get rid of nonlinearity due to delays in the integration phase that could take place in a multi-ASIC system. The ASIC uses 5- and 3.3-V bias voltages, the overall power consumption being 280 mW. The ASIC was tested with a $12\times12$ SiPMs matrix coupled with a 3 inch LaBr 3, providing good spectroscopic performances (2.6% at the 137Cs photopeak emission energy of 662 keV), and was also tested irradiating the SiPMs with fast, bright NUV light pulses, in order to explore the ASIC wide range coverage while simulating the scintillation light emission of a lanthanum bromide crystal. [ABSTRACT FROM AUTHOR]

This letter presents a dual-polarization beamformer chip for fifth-generation (5G) applications. The chip leverages a vector-sum phase shifter (VSPS) approach and single-ended design, allowing a reduced control circuitry complexity. The use of the VSPS translates in both phase shift and gain control, as shown in the system analysis. This beamformer is suitable for four dual-polarized antennas, achieving high gain control for each element. The performance can be summarized as a 1-dB compression point of 11dBm, while having an rms phase and amplitude error lower than 0.5° and 0.4 dB, respectively, at the maximum constant magnitude gain circle. Moreover, it is shown that the design can afford tapering despite relying only on the VSPS for gain control. [ABSTRACT FROM AUTHOR]

In this manuscript we present a true pulse-on-demand laser design concept using two different approaches. First, we present a fiber master oscillator power amplifier (MOPA) based quasi-continuous wave (CW) laser, working at high modulation bandwidths, for generation of nanosecond pulses. Second, we present a hybrid chirped pulse amplification (CPA)-based laser, combining a chirped-pulse fiber amplifier and an additional solid-state amplifier, for generation of femtosecond pulses. The pulse-on-demand operation is achieved without an external optical modulator/shutter at high-average powers and flexible repetition rates up to 40 MHz, using two variants of the approach for near-constant gain in the amplifier chain. The idler and marker seed sources are combined in the amplifier stages and separated at the out using either wavelength-based separation or second harmonic generation (SHG)-generation-based separation. The nanosecond laser source is further applied to high throughput processing of thin film materials. The laser is combined with a resonant scanner, using the intrinsic pulse-on-demand operation to compensate the scanner's sinusoidal movement. We applied the setup to processing of indium tin oxide (ITO) and metallic films on flexible substrates. [ABSTRACT FROM AUTHOR]

A laser scanner is a powerful tool for 3-D geometry measurement. The amplitude-modulated continuous-wave (CW) laser scanner, which benefits from high accuracy measurement operating in the intermediate range, is suitable for high-precision 3-D industrial inspection. However, due to the limited dynamic range, laser scanners suffer from data loss and deterioration. This poses challenges for 3-D modeling, conversion of 3-D point cloud data to 3-D solid data, and so on. We chose the operation wavelength in the 1530-nm region. The dynamic range of an amplitude-modulated CW laser scanner was enhanced by the implementation of a combination of a low-noise and high-gain optical preamplifier and p-i-n photodiodes, a pellicle beamsplitter, and automatic gain control using a polarization-independent high-speed variable optical attenuator based on electrooptic ceramics in the receiver. In these manners, receiver sensitivity of −72 dBm was achieved and receiver dynamic range of around 37 dB was realized. We expect that our results contribute to high-definition industrial inspection for Industry 4.0. [ABSTRACT FROM AUTHOR]

This brief presents a variable-gain low-noise amplifier (VG-LNA) with a common gate (CG) cross-summing configuration, which is fabricated using a 65-nm RF CMOS process. It has a wide gain control range as well as a high input 1 dB gain compression point (IP1dB) at high-gain by introducing a split common-gate transistor (SCGT) technique. In addition, output phase compensation is achieved by adopting a tuning capacitor at the cascode node. This LNA is designed as 2-stage cascode, and the area excluding the pad is 0.2 mm2. It consumes 25.2 mW with a 1.2-V power supply. It shows a gain of 25 dB and a noise figure of 3.4 dB at 22 GHz. The measured minimum IP1dB is −27.5 dBm, and the root-mean-square phase error is 0.34° over the gain control range of 14 dB at 22 GHz. [ABSTRACT FROM AUTHOR]

PurposeHumans with amblyopia have an asymmetry in binocular vision: neural signals from the amblyopic eye are suppressed in the cortex by the fellow eye. The purpose of this study was to develop new models and methods for rebalancing this asymmetric binocular vision by manipulating the contrast and luminance in the two eyes.MethodsWe measured the perceived phase of a cyclopean sinewave by asking normal and amblyopic observers to indicate the apparent location (phase) of the dark trough in the horizontal cyclopean sine wave relative to a black horizontal reference line, and used the same stimuli to measure perceived contrast by matching the binocular combined contrast to a standard contrast presented to one eye. We varied both the relative contrast and luminance of the two eyes' inputs, in order to rebalance the asymmetric binocular vision.ResultsAmblyopic binocular vision becomes more and more asymmetric the higher the stimulus contrast or spatial frequency. Reanalysing our previous data, we found that, at a given spatial frequency, the binocular asymmetry could be described by a log-linear formula with two parameters, one for the maximum asymmetry and one for the rate at which the binocular system becomes asymmetric as the contrast increases. Our new data demonstrates that reducing the dominant eye's mean luminance reduces its suppression of the non-dominant eye, and therefore rebalances the asymmetric binocular vision.ConclusionsWhile the binocular asymmetry in amblyopic vision can be rebalanced by manipulating the relative contrast or luminance of the two eyes at a given spatial frequency and contrast, it is very difficult or even impossible to rebalance the asymmetry for all visual conditions. Nonetheless, wearing a neutral density filter before the dominant eye (or increasing the mean luminance in the non-dominant eye) may be more beneficial than the traditional method of patching the dominant eye for treating amblyopia.

Cholinergic and noradrenergic neuromodulation of the synaptic transmission from cortical layer 6 of the primary somatosensory cortex to neurons in the posteromedial thalamic nucleus (PoM) was studied using an in vitro slice preparation from young rats. Cholinergic agonist carbachol substantially decreased the amplitudes of consecutive excitatory postsynaptic potentials (EPSPs) evoked by a 20 Hz five pulse train. The decreased amplitude effect was counteracted by a parallel increase of synaptic frequency-dependent facilitation. We found this modulation to be mediated by muscarinic acetylcholine receptors. In the presence of carbachol the amplitudes of the postsynaptic potentials showed a higher trial-to-trial coefficient of variation (CV), which suggested a presynaptic site of action for the modulation. To substantiate this finding, we measured the failure rate of the excitatory postsynaptic currents in PoM cells evoked by “pseudominimal” stimulation of corticothalamic input. A higher failure-rate in the presence of carbachol indicated decreased probability of transmitter release at the synapse. Activation of the noradrenergic modulatory system that was mimicked by application of norepinephrine did not affect the amplitude of the first EPSP evoked in the five-pulse train, but later EPSPs were diminished. This indicated a decrease of the synaptic frequency-dependent facilitation. Treatment with noradrenergic α-2 agonist clonidine, α-1 agonist phenylephrine, or β-receptor agonist isoproterenol showed that the modulation may partly rely on α-2 adrenergic receptors. CV analysis did not suggest a presynaptic action of norepinephrine. We conclude that cholinergic and noradrenergic modulation act as different variable dynamic controls for the corticothalamic mechanism of the frequency-dependent facilitation in PoM.

A Ka-band variable-gain phase shifter (VGPS) using a multi-vector summation method is proposed, which represents both phase and amplitude by summing the I and Q signals of multiple vectors. The VGPS has an orthogonal phase and gain control function with a wide gain-control dynamic range because it is designed to keep the input and output impedances almost constant regardless of the control states. It shows a measured RMS phase error of 2.9 ° during 17.3 dB gain control and that of 3.5 ° during simultaneous 17.3 dB gain and 360 ° phase control without any calibration from 30 to 32.5 GHz. The measured average insertion loss ranges from −4 to −2.8 dB from 28 to 33 GHz. It is implemented in a 65-nm RF CMOS process with the size of 0.21 mm2 excluding pads. [ABSTRACT FROM AUTHOR]