Gain Range Research Articles

Receiving Paths Improvement of Digital Phased Array Antennas Using Adaptive Dynamic Range

In contemporary radar technology, the observation and detection of objects with low radar cross-sections remains a significant challenge. A multi-functional radar model employing a digital phased array antenna system offers notable advantages over traditional radar in addressing this issue. Nonetheless, to fully capitalize on these benefits, improving the structure of the receiving path in digital transceiver modules is crucial. A method for improving the digital receiving path model by implementing a matched filter approach is introduced. Given that the return signals from objects are often lower than the internal noise, the analog part of the digital transceiver modules must ensure that its dynamic range aligns with the level of this noise and the weak signal. The output signal level of the analog part must correspond to the allowable input range of the analog-to-digital converter. Improvements in the receiving path to achieve a fully matched model can reduce errors in the phase parameters and amplitudes of the useful signal at the output. The simulation results presented in this paper demonstrate a reduction in amplitude error by approximately 1 dB and a phase error exceeding 1.5 degrees for the desired signal at the output of each receiving path. Consequently, these improvements are expected to enhance the overall quality and efficiency of the spatial and temporal accumulation processes in the digital phased array antenna system. Furthermore, to maintain the matched filter model, we also propose incorporating an adaptive “pseudo-expansion” of the linear gain range. This involves adding a feedback stage with an automatic and adaptive bias voltage adjustment for the intermediate-frequency preamplifier in the analog part of the receiving path. Simulations to qualitatively verify the validity of this proposal are conducted using data from practical operational radar system models.

Stable and Tunable Erbium Ring Laser by Rayleigh Backscattering Feedback and Saturable Absorber for Single-Mode Operation

This work demonstrates a high-quality erbium-doped fiber (EDF) ring laser in the L-band gain range by combining the Rayleigh backscattering (RB) feedback signal and unpumped EDF induced saturable absorber (SA) filter. The optical filter effect induced by the RB feedback injection and EDF SA could generate single-longitudinal-mode (SLM) behavior and shrink the linewidth to sub-kHz. The output linewidth, power, and optical-signal-to-noise ratio (OSNR) of the fiber ring laser were also shown within the 42 nm wavelength bandwidth of 1565.0 to 1607.0 nm. Also, the instabilities of output power and central wavelength of each lasing lightwave were analyzed with a measurement time of 45 min.

A 28 GHz balun‐first LNA with db‐linear 32 db gain range for 5 G applications

AbstractThis letter presents a 28 GHz balun‐first low noise amplifier (LNA) featuring a wide dB‐linear variable gain range. The architecture of LNA includes three‐stage cascode amplifiers. An integrated balun at the input stage provides RF ESD protection and converts a single‐ended signal to a differential one (S‐to‐D). A transformer‐based dual‐resonant matching network is designed and analyzed to achieve wideband performance. To realize a continuous dB‐linear variable gain range and consistent input/output matching, gain control is implemented in the second stage using a 5‐bit digital‐to‐analog converter (DAC) for a 32 dB gain range. The DAC can generate a nonlinear analog voltage to control the gate of the common‐gate transistor in the second cascode stage, inversely compensating for the nonlinear gain variations of the cascode amplifier. The LNA is fabricated in 65‐nm CMOS process with a core size of 0.154 mm². Measurement results exhibit a maximum gain of 33.5 dB and a minimum noise figure (NF) of 3.65 dB with a 3‐dB bandwidth of 23–29.5 GHz. The measured variable gain range is approximately 32 dB across 32 different gain states, with a linear gain step of ~1 dB per state and an IP1dB ranging from −6.5 dBm to −35.25 dBm. The power consumption is 35.4–48 mW from a 1.2 V supply voltage.

Review of Techniques for Resonant Converters With Wide Voltage Gain Range Applications

Review of Techniques for Resonant Converters With Wide Voltage Gain Range Applications

Multipeak ultraviolet lasing based on F-P mode from in-situ ZnO nanowire

Abstract High-quality ultraviolet singlemode and multimode lasing from zinc oxide nanowires are highly desirable. In this paper, we achieve high-Q lasing oscillation in vertically grown Zinc oxide (ZnO) microwires. The broad gain range reaches 13 lasing modes under high-energy excitation. We observe multiple peak emissions from the Fabry-Perot (F-P) lasing mode. In contrast, nanorod arrays with low aspect ratios exhibit amplified spontaneous emission (ASE) due to significant diffraction losses. Our work demonstrates that high-quality ZnO nanowires with an appropriate aspect ratio realize high-Q ultraviolet multipeak lasing based on F-P mode. These findings will benefit the design and fabrication of nanolasers based on nanowires.

Soft‐switching boundary and piecewise control of LLC converter with hybrid modulation

AbstractThe voltage gain range of LLC converter can be effectively broadened by using the hybrid modulation of phase‐shift modulation (PSM) and pulse frequency modulation (PFM). However, the harmonic of resonant tank increases dramatically in PSM mode, and the first harmonic approximation is no longer suitable for solving the voltage gain. Moreover, the conditions for soft switching in PSM mode are not clear. Meanwhile, the small‐signal models of the converter in different modulation modes are quite different, and it is difficult for a fixed controller to ensure a good dynamic performance of the converter in both modulation modes. To address above issues, a voltage gain modeling method of PSM mode LLC converter is proposed. By establishing the function between input current and resonant current, the voltage gain model of the converter is obtained according to the power conservation. Moreover, considering the parasitic capacitance charge and resonant current commutation time, the condition for soft switching is derived. Furthermore, a control strategy of LLC converter in hybrid modulation is proposed. The piecewise proportional integral (PI) controller is adopted, and the parameters of the controller are dynamically adjusted with the modulation mode, so that the converter has excellent dynamic performance in both modes. And the hysteresis control is used to ensure the stability of mode switching. An experimental prototype with 200–340 V input and 28 V/1 kW output was built based on gallium nitride (GaN) devices. The peak efficiency was 97.82%, and the power density was 65.76 w/in3.

Integrated Quasi-Two-Stage Buck-LC Converter With Wide Voltage Gain Range

Integrated Quasi-Two-Stage Buck-<i>LC</i> Converter With Wide Voltage Gain Range

A single-bridge interleaved three-level LLC resonant converter with current sharing capability for fuel cell system

This paper propose a wide gain single-bridge interleaved three-level LLC resonant converter with current sharing capability. This novel converter offers numerous advantages, including low cost, low current ripple, reduced voltage and current stress, widely gain range, high efficiency, good current sharing capability and versatile application scalability. Utilizing the three-level inverter + full-wave rectifier LLC converter as a representative case, the paper conducts an in-depth analysis and research on the proposed method. Finality, a 600 W experimental prototype was constructed and tested. Experimental results reveal that the proposed converter exhibits lower current ripple and a broader gain range. Moreover, the converter shows good current sharing capability (with a resonant element tolerance of 10%, the current error between the two phases does not exceed 12%) and high efficiency (peaking at 95.8%).

Mechanism analysis and application of multi-dimensional single potential well stochastic resonance system

Currently, the focus of stochastic resonance (SR) research is primarily on bistable systems, and classical bistable SR systems have the problems of low dimension, inconvenient parameter adjustment, and high threshold for SR effects. In this paper, based on the classic bistable system, a class of multi-dimensional single potential well SR systems without transition threshold is proposed and applied to signal processing. Firstly, the mechanism of double potential well SR and single potential well SR is studied. On this basis, a kind of multi-dimensional single potential well SR system is defined and its theoretical conditions are analyzed. Then a specific four-dimensional single potential well SR system is constructed, and the dynamics of the system is analyzed. The gain range and the approximate relationship between the system input and the four-dimensional output are derived. Finally, the four-dimensional single potential well SR system is applied to the processing of various signals. The experimental results show that the constructed system has good noise reduction and feature amplification effects on noisy signals through the advantages of multi-dimensional output, and can be used to highlight the fault feature frequency in bearing fault signals.

Trunk distortion weakens the tree productivity revealed by half-sib progeny determination of Pinus yunnanensis

Twisted trunks are not uncommon in trees, but their effects on tree growth are still unclear. Among coniferous tree species, the phenomenon of trunk distortion is more prominent in Pinus yunnanensis. To expand the germplasm of genetic resources, we selected families with excellent phenotypic traits to provide material for advanced generation breeding. The progeny test containing 93 superior families (3240 trees) was used as the research material. Phenotypic measurements and estimated genetic parameters (family heritability, realistic gain and genetic gain) were performed at 9, 15, and 18 years of age, respectively. The genetic evaluation yielded the following results (1) The intra-family variance component of plant height (PH) was greater than that of the inter-family, while the inter-family variance components of other traits (diameter at breast height (DBH), crown diameter (CD), height under branches (HUB), degree of stem-straightness (DS)) were greater than that of the intra-family, indicating that there was abundant variation among families and potential for selection. (2) At half rotation period (18 years old), there was a significant correlation among the traits. The proportion of trees with twisted trunks (level 1–3 straightness) reached 48%. The DS significantly affected growth traits, among which PH and DBH were the most affected. The volume loss rate caused by twisted trunk was 18.06-56.75%, implying that trunk distortion could not be completely eliminated after an artificial selection. (3) The influence of tree shape, crown width, and trunk on volume increased, and the early-late correlation between PH, DBH and volume was extremely significant. The range of phenotypic coefficient of variation, genetic variation coefficient and family heritability of growth traits (PH, DBH, and volume) were 44.29-127.13%, 22.88-60.87%, and 0.79–0.83, respectively. (4) A total of 21 superior families were selected by the method of membership function combined with independent selection. Compared with the mid-term selection (18 years old), the accuracy of early selection (9 years old) reached 77.5%. The selected families’ genetic gain and realistic gain range were 5.79-19.82% and 7.12-24.27%, respectively. This study can provide some useful reference for the breeding of coniferous species.

Energy analysis, mass transfer, and rehydration kinetics of okra dried using evacuated tube solar dryer

ABSTRACT Okra (Abelmoschus esculentus L.), like most fruits and vegetables, deteriorates quickly after harvesting due to its high moisture content and respiration rate. To preserve it and mitigate the post-harvest losses, a developed evacuated tube solar dryer (ETSD) with heat pipes was used to dry fresh okra. Thermal profiling of the ETSD was carried out to investigate the range of temperature gain inside the drying chamber. The effect of different blanching temperatures, viz. 70, 80, and 90°C, on drying characteristics and physical properties like color, water activity, and rehydration kinetics of okra were investigated. The energy efficiency of the collector ranged from 13.21% to 42.67%. Similarly, the convective mass transfer coefficient was calculated and ranged from 3.41 × 10−07 to 8.57 × 10−07 m/s. The okra blanched at 80°C, showing maximum greenness retention and lower water activity. The rehydration ratio was 6.05, 7.19, 7.73, and 7.41 for control, and okra blanched at 70, 80, and 90°C. The rehydration kinetics were analyzed using four distinct models: Peleg, Weibull, exponential, and first order. The Weibull model demonstrated the most accurate fit to the data. It is suggested that okra blanched at 80°C and dried under ETSD gives better retention of color and a higher mass transfer and rehydration rate.

Microsatellite Yaw-axis Attitude Control System Using Model Reference Adaptive Control Based PID Controller

This paper presents a Model Reference Adaptive Control (MRAC) based Proportional Integral and Derivative (PID) controller for microsatellite yaw-axis Attitude Control System (ACS). The objective is to combine the algorithm of MRAC with PID to improve the performance of a microsatellite system especially settling time. MRAC based PID controller for yaw-axis ACS was modelled and simulated in MATLAB/Simulink to meet transient response characteristics specifications. The performance of the system was evaluated in terms of rise time, settling time, maximum overshoot, and steady-state error including energy consumption measured based on armature voltage of the direct current motor. The simulation results revealed that the proposed system meets all the performance specifications and outperformed classical PID controller for adaption gain of 0.2 to 20. When compared with PID and Proportional Derivative (PD) based Controllers in previous study for adaption gain of 10, 15, and 20, the proposed system proved to be superior. Generally, the choice of the MRAC based PID controller considering the range of adaption gain (γ = 0.1 to 20) should be based on either transient response advantage or energy consumption or even both over PID controller. The significance of this study is that an MRAC based PID controller that offered wide range of adaption capability for microsatellite ACS has been proposed.

Three‐phase LLC resonant converter with variable magnetizing inductance to extend gain range

Three‐phase LLC resonant converter with variable magnetizing inductance to extend gain range

Lattice ultrasensitivity produces large gain in E. coli chemosensing.

E. coli use a regular lattice of receptors and attached kinases to detect and amplify faint chemical signals. Kinase output is characterized by precise adaptation to a wide range of background ligand levels and large gain in response to small relative changes in ligand concentration. These characteristics are well described by models which achieve their gain through equilibrium cooperativity. But these models are challenged by two experimental results. First, neither adaptation nor large gain are present in receptor binding assays. Second, in cells lacking adaptation machinery, fluctuations can sometimes be enormous, with essentially all kinases transitioning together. Here we introduce a far-from equilibrium model in which receptors gate the spread of activity between neighboring kinases. This model achieves large gain through a mechanism we term lattice ultrasensitivity (LU). In our LU model, kinase and receptor states are separate degrees of freedom, and kinase kinetics are dominated by chemical rates far-from-equilibrium rather than by equilibrium allostery. The model recapitulates the successes of past models, but also matches the challenging experimental findings. Importantly, unlike past lattice critical models, our LU model does not require parameters to be fine tuned for function.

Optimal range of gestational weight gain for singleton pregnant women: a cohort study based on Chinese specific body mass index categories

BackgroundThe purpose was to explore the optimal proportion of GWG in Chinese singleton pregnant women according to Chinese specific body mass index (BMI) categories.MethodsA retrospective cohort study with 16,977 singleton pregnant women was conducted. Among the including subjects, 2/3 of which were randomly imported into the training set for calculating the optimal GWG ranges using the percentile method, the Odd Ratio (OR) method, and the combined risk curve method. And another third of the subjects were used to evaluate the GWG ranges obtained. The detection rate of adverse outcomes of pregnant women was used to evaluate the applicability of GWG obtained. The range corresponding to the lowest detection rate is the recommended GWG range in this study.ResultsAccording to the percentile method, the suitable GWG of pregnant women with underweight, normal weight, overweight or obesity before pregnancy were 12.0 ∼ 17.5 kg, 11.0 ∼ 17.0 kg, and 9.0 ∼ 15.5 kg, respectively. According to the OR method, the suitable GWG range were 11 ∼ 18 kg, 7 ∼ 11 kg, and 6 ∼ 8 kg, respectively. According to the combined risk curve method, the suitable GWG range were 11.2 ∼ 17.2 kg, 3.6 ∼ 11.5 kg, and − 5.2 ∼ 7.0 kg, respectively. When the GWG for different BMI categories were 11 ∼ 18 kg, 7 ∼ 11 kg, and 6 ∼ 8 kg, the pregnant women have the lowest detection rate of adverse maternal and infant outcomes.ConclusionsThe recommended GWG based on this study for underweight, normal, overweight or obese pregnant women were 11 ∼ 18 kg, 7 ∼ 11 kg, and 6 ∼ 8 kg, respectively.

Cold-evoked potentials in Fabry disease and polyneuropathy.

Fabry disease (FD) causes cold-evoked pain and impaired cold perception through small fiber damage, which also occurs in polyneuropathies (PNP) of other origins. The integrity of thinly myelinated fibers and the spinothalamic tract is assessable by cold-evoked potentials (CEPs). In this study, we aimed to assess the clinical value of CEP by investigating its associations with pain, autonomic measures, sensory loss, and neuropathic signs. CEPs were examined at the hand and foot dorsum of patients with FD (n = 16) and PNP (n = 21) and healthy controls (n = 23). Sensory phenotyping was performed using quantitative sensory testing (QST). The painDETECT questionnaire (PDQ), FabryScan, and measures for the autonomic nervous system were applied. Group comparisons and correlation analyses were performed. CEPs of 87.5% of the FD and 85.7% of the PNP patients were eligible for statistical analysis. In all patients combined, CEP data correlated significantly with cold detection loss, PDQ items, pain, and autonomic measures. Abnormal CEP latency in FD patients was associated with an abnormal heart frequency variability item (r = -0.684; adjusted p = 0.04). In PNP patients, CEP latency correlated significantly with PDQ items, and CEP amplitude correlated with autonomic measures (r = 0.688, adjusted p = 0.008; r = 0.619, adjusted p = 0.024). Furthermore, mechanical pain thresholds differed significantly between FD (gain range) and PNP patients (loss range) (p = 0.01). Abnormal CEPs were associated with current pain, neuropathic signs and symptoms, and an abnormal function of the autonomic nervous system. The latter has not been mirrored by QST parameters. Therefore, CEPs appear to deliver a wider spectrum of information on the sensory nervous system than QST alone.

A High Step-Down SiC-Based T-Type LLC Resonant Converter for Spacecraft Power Processing Unit

A spacecraft power processing unit (PPU) is utilized to convert power from solar arrays or electric batteries to the payload, including electric propulsion, communication equipment, and scientific instruments. Currently, a high-voltage converter is widely applied to the spacecraft PPU to improve power density and save launch weight. However, the high voltage level poses challenges such as high step-down ratios and high power losses. To achieve less conduction loss, a SiC-based T-type three-level (TL) LLC resonant converter is proposed. To further broaden the gain range and achieve high step-down ratios, a variable frequency and adjustable phase-shift (VFAPS) modulation scheme is proposed. Meanwhile, the steady-state time-domain model is established to elaborate the operation principles and boundary conditions for soft switching. Furthermore, the optimal resonant element design considerations have been elaborated to achieve wider gain range and facilitate easier soft switching. Furthermore, the numerical solutions for switching frequency and phase shift (PS) angle under each specific input could be figured out. Finally, the effectiveness of this theoretical analysis is demonstrated via a 500-W experimental prototype with 650∼950-V input and constant output of 48-V/11-A.

A 60 dB gain range programmable gain current amplifier for ultrasound sensing

This article presents a programmable gain current amplifier (CA) for ultrasound sensing applications. The design proposed consists of a current divider and a close-loop current amplifier. The CA utilizes switches to adjust the resistance of the shunt resistors and feedback resistors to achieve variable gain, thus realizing the time gain compensation (TGC) function. The proposed CA implemented in 180-nm BCD technology occupies an active area of 0.059 mm2. Measurement results show that the CA achieves a maximum gain of 36.6 dB and a gain range of 60 dB. The average input-referred noise spectral density is 0.32 pA/√Hz at maximum gain condition while consuming a power of 1.07 mW.

Reconfigurable Low-Power CMOS Amplifier Stages for Broadband Impedance Spectroscopy

In this paper, a fully differential amplifier is proposed in a 1.8 V-0.18 μm CMOS (Complementary Metal-Oxide-Semiconductor) technology, which can accommodate both voltage (V-mode) and current (C-mode) inputs. Post-layout simulation results show a fixed gain amplifier exhibiting a 26 dB (V-mode)/89 dBΩ (C-mode) gain and a programmable gain amplifier featuring a 6–26 dB gain, overall yielding a 26.8–46.4 dB dB (V-mode)/89.6–109.2 dBΩ (C-mode) programmable gain range, with a 100 MHz bandwidth and a power and area consumption of 360.5 µW and 0.0177 mm2, respectively. This amplifier has been designed considering the constraints and specifications (including low voltage, low power, reduced noise and high common mode rejection ratio) for its use in an analogue Lock-in-based Frequency Response Analyser-Impedance Spectroscopy (FRA-IS) device. The proposed design introduces a novel fully differential open-loop structure based on a transconductance–transimpedance (TC-TI) topology for high performance applications with a broad programmable bandwidth. To compare this work, different figures of merit (FoMs) are introduced as well as a comparison table with other simulated and experimental results, reporting an overall better performance in terms of gain, frequency and power-area consumption.

Optimizing ultrasound Doppler measurement precision: a comprehensive experimental approach

Experimental studies were conducted utilizing advanced equipment comprising a generator, tubing system, pump module, sonographer, and PC. The generator serves as the central component connected by tubes to the pump, forming a closed circuit. A tee in the tubing set prevents Doppler fluid leakage, with the fluid poured through a special funnel into the circuit post-connection. The Doppler fluid is evenly mixed by shaking its bottle to enhance signal strength. The entire system is sealed. The centrifugal pump generates continuous flows; different power modes were tested for 30 minutes each, with frequency shifts measured at angles α=15°, 30°, and 60°. Pump disconnection from the power supply prevents liquid entry during tubing connection. The pump module housing includes ventilation holes. A 3 by 8 cm Doppler prism, treated with ultrasonic gel, was connected to the tubing to capture data. A sonographer emitting signals at 2 MHz, with a gain range of 10 to 40 dB, was utilized for sound spectra analysis. High-mode operation, 4 microseconds pulse duration, and a 32 microseconds receiver gate were set. The ultrasound apparatus dimensions were 230 x 236 x 168 mm, with a power consumption of 27 VA. Data visualization was facilitated by an LED panel, with adjustable acoustic signal volume. A USB interface enabled connection to a PC for ease of use and data analysis. Special software facilitated graph generation depicting frequency vs. time dependence measurements. Frequency analysis yielded average (f-mean) and maximum (f-max) frequency values, with f-mean utilized to measure Doppler effect frequency shift. The presented data showcases various pump speeds and incidence angles, each yielding distinctive frequency characteristics.