Gain Range Research Articles

Hybrid-Type Dual Active Bridge DC–DC Converter for Ultrawide Input-Voltage Range

This paper proposes a hybrid-type dual active bridge (H-DAB) topology and extended gain control (EG) method applied to the ultra-wide input-voltage range. The H-DAB is obtained by adding an auxiliary half-bridge to the conventional current-fed dual active bridge (CF-DAB) topology. The auxiliary half-bridge can assist the CF-DAB to achieve ZVS on the one hand, and further expand the voltage gain range on the other. The proposed extended gain control (EG) expands the input voltage range of ZVS for all switches by calculating the optimal intermediate bus voltage. In addition, the backflow power has also been drastically reduced. The proposed piecewise control strategy simplifies the complexity of control. The proposed topology and the control method are verified by the experimental results of a 500 W prototype. The input voltage range is 27 – 240 V and the output voltage is 375 V. The experimental results proved that the proposed scheme achieves ZVS of all switches in a wide input voltage range and power range, and the efficiency is improved.

A Wideband Low-Loss CMOS Attenuator With dB-Linear Gain Tuning for W-Band Applications

This paper presents the design of a wideband low-loss attenuator at W band. The reflective-type attenuation topology is employed to reduce loss and provide flat gain response. Optimizations of the switched-resistor-based reflective loads enable simultaneous direct-digital control and dB-linear gain tuning. The proof-of-concept W-band attenuator is implemented in 40-nm CMOS technology. Measurement results prove that the proposed attenuator can cover 15.5 dB gain range with 0.5 dB step and < 0.2 dB RMS gain error over 70–110 GHz band. The insertion loss is 3.0–3.8 dB across 70–110 GHz, implying low loss and flat gain response.

Novel low noise amplifier approach for deep brain stimulation

This paper presents an analysis for a multi-stage Low Noise Amplifier (LNA) for application on deep brain stimulation. A low noise amplifier (LNA) with high gain, moderate bandwidth and reduced noise is designed and simulated using LT Spice and PTM BSIM4 CMOS models. The novel LNA circuit topology is proposed which uses a cascaded style to improve mid-band gain of an LNA. The proposed LNA achieves a gain margin which ranges between 60-67 (dB), 2X times; Phase Margin which ranges between 145 to 154 (deg), 3X times; Gain which ranges between 66 to 75 (dB), 2X times and bandwidth from kHz to MHz range. The current biasing circuit is used for enhancing stability and gain range. Also, optimal noise figure is achieved with the help of cascading input matching along with source degeneration technique.

An Improved Cascading Scheme to Achieve Wide Gain Range and Efficiency Optimization for Resonant Forward Converter

This paper presents an improved cascading scheme for the resonant forward converter to widen the gain range while reducing losses and complexity by removing two filtering components. The efficiency is optimized for the second stage through the phase-shift controlled current injection directly from the first stage. Then, the improvement is achieved by adaptively adjusting the resonant duration according to the voltage-stress-control determined on-time, and thus, the root mean square values of current in transformer windings are reduced. Based on detailed analysis and design considerations, the experimental results validate the effectiveness of the proposed scheme.

High-Gain and High-Efficiency Flexible Nonsymmetrical Metamaterial Tag

A flexible nonsymmetrical metamaterial (FNM) tag with high gain, high efficiency and wide readable angle range is proposed here, whose working band is 900MHz-930MHz. We improved impedance match between tag's antenna and chip to reduce the mismatch loss and increase radiation efficient of the tag by loading border cross units with top or bottom defaulted (BCUT/BCUB) units above and below the central folded dipole. Furthermore, the proposed tag is in size of 95mm×57mm×0.23mm, and it can realize 5dBi realized gain and radiation efficient of 89.13%, and 54m reading distance when the reader's effective isotropic radiated power is 42dBm if it's on a plane; and when it is conformal to cylinders whose radius over 26mm, the tag also can work at 900-930MHz, perform over 80% efficient and realize over 35m reading distance in measurement.

A Structure-Reconfigurable LLC Resonant Converter With Wide Gain Range

In this paper, a structure-reconfigurable LLC (SR-LLC) resonant converter is proposed for wide output voltage applications. The converter can operate in half-bridge mode or full-bridge mode by modulating the driving signal of the switches. Four operation modes with scaled voltage gains are obtained by the independent or combined operation of resonant tanks. Compared with the conventional full-bridge LLC converter, the voltage gain range is greatly extended without extra switches. The consistent resonance parameters of two tanks allow four operating modes to have the same resonant frequency, which facilitates the design of magnetic components. Moreover, zero-voltage switching (ZVS) of the primary-side MOSFETs can be achieved in all modes. A 3.3-kW prototype with 75 V-450 V output voltage is built to verify the feasibility and effectiveness of the proposed converter. The peak efficiency of the prototype is 97.3%, and the efficiency curve is smooth in the ultra-wide output voltage range.

A Phase-Shift-Modulated Resonant Two-Switch Boosting Switched-Capacitor Converter and Its Modulation Map

In this paper, a Phase-shift-modulated (PS) Resonant Two-switch Boosting Switched-capacitor Converter (RTBSC) and its modulation map are proposed. Compared with the traditional RTBSC, all diodes are replaced by active switches and then phase-shift modulation is applied. The advantages of the modified topology are obtained as follow. 1) The voltage gain can be regulated efficiently either below or above the nominal value even at light-load condition, making it suitable for applications with voltage fluctuations; 2) The conduction loss is reduced by replacing all diodes in RTBSC with low turn-on resistance transistors, especially for high-order and high-gain configuration; 3) All switches achieve the zero-voltage-switching (ZVS) turn-on operation; 4) The soft-charging property smooths the current profile. Aside from the topology modification, a comprehensive analysis of operation principle, voltage gain, component stress and ZVS region is given. On the basis, a modulation map with the optimal operation region is proposed. It provides a guideline to operate and design such converters in the target gain range, low component stress and ZVS region, making up for the lack of modulation map and design guideline in aforementioned literatures. A 120W prototype with low-voltage side 43-60V and high-voltage side 150V was designed to verify the above analyses.

A Millimeter-Wave Antipodal Linearly Tapered Slot Antenna Array for 5G Wireless Communication

This paper presents an antipodal linearly tapered slot antenna (ALTSA) array with the newly emerging substrate-integrated coaxial line (SICL) technology. Each element of the proposed array consists of two vertically stacked antipodal tapered slot antennas (TSA) with the inner conductor of a SICL as the shared fin. The vertical symmetry of this radiating element structure significantly suppresses the cross-polarization level. By employing a SICL-based power splitter with differential outputs, a two-element array with horizontal symmetry is formed. With the inner conductors of two parallel SICLs combined as the flaring metal shared by adjacent tapered slots, the main beam squint is effectively suppressed. Experimental results show an actual −10-dB impedance bandwidth (BW) of 24.5∼34.4 GHz, and the realized gain range measured is 16.1∼18.7 dBi. The cross-polarization levels are −39.4 dB/−40.7 dB at 30 GHz for the E-/H-planes. The measured results agree well with the simulated data which demonstrates the feasibility of the proposed SICL-based ALTSA scheme in the potential 5 G·millimeter-wave (mmWave) applications.

Design of Flexible Multi-Band Miniature Antenna Based on Minkowski Fractal Structure and Folding Technique for Miniature Wireless Transmission System

In light of the predicament concerning the small gain and narrow frequency range of miniature antennas, this paper employs the implementation of a fractal repeating array structure and a double-layer folding antenna structure. Through these measures, the miniature antenna is endowed with a high gain and an expansive frequency range, all within its diminutive size. The paper presents an exquisite and high-gain flexible multi-band antenna, utilizing a dielectric substrate composed of the flexible material polyimide, with a thickness of merely 0.1 mm. The implementation of this flexible material bestows a feathery mass of merely 4 mg upon the antenna, enabling it to seamlessly conform to various shapes. This makes it particularly well-suited for employment within miniature wireless transmission systems and compact mobile communication devices. In an endeavor to enhance impedance matching and radiation characteristics, the Minkowski fractal structure is ingeniously incorporated as the repeating array element. This repeating array structure assumes a pivotal role and, when combined with the double-layer folding antenna structure, achieves the objective of miniaturization. Remarkably, the antenna’s dimensions measure a mere 0.04 λ0 × 0.026 λ0 (λ0 @ 2.4 GHz). The proposed antenna boasts a remarkably diminutive volume of merely 5 × 3 × 0.1 mm3, with the measured and simulated results exhibiting a striking concurrence. Both sets of results demonstrate resonance across multiple frequencies, namely, 2.4 GHz, 5.2 GHz and 5.8 GHz. Furthermore, within the effective frequency range, the antenna attains a maximum gain of 1.65 dBi and 4.37 dBi, respectively.

Effects of a low glycemic index or low glycemic load diet on pregnant women at high risk of gestational diabetes: A meta-analysis of randomized controlled trials

AimsTo evaluate the effect of low glycemic index or low glycemic load diets on maternal and neonatal outcomes at high risk of gestational diabetes mellitus (GDM). Data synthesisSeveral databases (PubMed, Cochrane Library, Web of Science, Embase, OVID, Clinical Trials. gov, China National Knowledge Infrastructure, China Biomedical Database, and Wanfang Database) were searched from January 1990 to January 2022 (updated to November 2022). Randomized controlled trials of low glycemic index diets interventions for women at high risk of GDM were included. From 2131 articles initially were screened, after eliminating duplicates, 1749 titles and abstracts were analyzed. 71 documents that met the inclusion criteria were selected and 3 documents were obtained through searching the reference lists. After reading the full text, 10 studies were retained. Two authors evaluated the studies, extracted data and conducted quality assessment independently. A total of 10 studies with 2304 patients met the inclusion criteria. Compared with the control group, a low glycemic index diet could control the range of weight gain (WMD -1.01, 95% CI -1.41 to -0.61), decrease the incidence of excessive weight gain (OR 0.69, 95% CI 0.54–0.87), lessen the incidence of large-for-gestational-age infants (OR 0.32, 95% CI 0.16–0.62) and reduce the incidence of preterm infants (OR 0.45, 95% CI 0.29–0.71). ConclusionA low glycemic index or low glycemic load diet could control maternal weight gain, reduce the incidence of excessive weight gain, and decrease the incidence of large-for-gestational-age infants and preterm infants in group with high risk of GDM. ProsperoCRD42022322697.

A functional logic for neurotransmitter corelease in the cholinergic forebrain pathway

The cholinergic system of the basal forebrain plays an integral part in behaviors ranging from attention to learning, partly by altering the impact of noise in neural populations. The circuit computations underlying cholinergic actions are confounded by recent findings that forebrain cholinergic neurons corelease both acetylcholine (ACh) and GABA. We have identified that corelease of ACh and GABA by cholinergic inputs to the claustrum, a structure implicated in the control of attention, has opposing effects on the electrical activity of claustrum neurons that project to cortical vs. subcortical targets. These actions differentially alter neuronal gain and dynamic range in the two types of neurons. In model networks, the differential effects of ACh and GABA toggle network efficiency and the impact of noise on population dynamics between two different projection subcircuits. Such cholinergic switching between subcircuits provides a potential logic for neurotransmitter corelease in implementing behaviorally relevant computations.

Metacarpophalangeal Joint Arthroscopy: Indications and Techniques through a Clinical Series.

Background Metacarpophalangeal (MCP) joint arthroscopy has been available for many years but sparingly used in typical orthopaedic and hand surgery daily practice. Difficult problems are solved with this technique in a practical and minimally invasive manner. This study describes our diverse experience and broad clinical applications of MCP arthroscopy as well as clinical results. It aims to highlight this technique as one of the tools for a fully trained hand surgeon, avoiding open management and its high complications rates. Methods We present a retrospective clinical series of 79 patients treated with MCP arthroscopy with a mean age of 44 years old. Demographics, surgery, and clinical outcomes were collected in standardized clinical assessments. Results We divided the sample into 20 articular metacarpal or proximal phalanx acute fracture with full functional fist and range of motion at 60 days after surgery. Regarding collateral tears, 12 were classified as acute and 47 as chronic. Two patients were reoperated for further gain range of motion. Conclusions We present an up-to-date publication of our experience in MCP arthroscopy and its applications, with a low complication rate and excellent clinical results. We encourage hand surgeons to incorporate this technique in MCP joint challenging issues. Level of Evidence IV.

Upper Extremity Serial Casting: An Ongoing Approach to Gain Range of Motion in Children With Cerebral Palsy After the COVID-19 Pandemic

Abstract Date Presented 04/21/2023 Upper extremity serial casting should be considered a beneficial nonsurgical treatment approach to address range of motion (ROM) limitations in children with cerebral palsy (CP) especially resulting from the negative effects caused by the COVID-19 pandemic. Primary Author and Speaker: Alicia Hana Heisler

Hybrid Control for Three-Level LLC Resonant Converter of Dual-Bridge for Wide Output Range

A three-level (TL) LLC resonant converter of dual-bridge (DB) with hybrid control modulation strategy is proposed for the wide output-voltage range and high input-voltage applications. The topology integrates two neutral-point-clamped arms (NPCs) through an auxiliary transformer, which forms a new controllable double-voltage structure and makes all MOSFETs hold half of the input voltage. Based on the characteristics of the new topology, a hybrid modulation strategy is proposed corresponding to three gain modes, which include conventional pulse frequency modulation (PFM) and fixed frequency phase shift modulation (FF-PSM). Compared to conventional modulation strategies, the proposed hybrid modulation strategy, which improves the output voltage gain range, achieves zero-voltage switching (ZVS) of all the MOSFETs and zero-current switching (ZCS) of rectifier diodes under wider operating voltage and full load range. To minimize the frequency window and improve the efficiency of the converter, the parameter optimization method is designed, which based on the characteristics of the modulation strategy and the relationship among the maximum output voltage gain, resonant current and turned-off current. At last, the experimental results of the 600W prototype are presented to confirm the theoretical and characterization analysis.

A Linear-in-Decibel Automatic Gain Control Amplifier With Dual Mode Continuous Gain Tuning

A reconfigurable fully integrated automatic gain control (AGC) amplifier is presented which is based on a dual mode continuous gain adjustment variable-gain amplifier (VGA). The VGA is realized based on the current-steering structure, achieving a linear-in-dB gain tuned by AGC’s feedback voltage. A current division active load is proposed, which provides additional gain control range and realizes gain robustness to process and supply variations without extra calibration. Simulated with Cadence IC, the maximum gain variations due to process and supply variations are 3.5 dB and 2.6 dB, respectively. By using dual mode gain tuning technique, the VGA achieves a total gain range of 68.2 dB. Both bandwidth and gain of the VGA are adjusted independently. The AGC is realized in UMC 55-nm CMOS technology with 0.026 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> core area. With the current division ratio K of 0.5, the proposed VGA achieves a linear-in-dB gain of 42.2 dB ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 30.0 to 12.2 dB) with less than 0.79 dB error. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 3 dB bandwidth can be adjusted from 80 MHz to 140 MHz and is insensitive to gain variations. The power dissipation is from 2.9 mW to 4.5 mW. This design features bandwidth scalability and the gain independent of bandwidth to achieve various applications.

High-frequency electric field intensity measurement based on frequency shift with high gain and wide frequency range

For the safe operation of equipment and personal safety protection in high-voltage environments, the precise measurement of the high-frequency electric field is of paramount importance. Optical electric field sensor (OES) is a current research trend for high-frequency electric field measurement but is generally limited by low sensitivity and the need for high-speed acquisition modules. Here, we propose a high-frequency electric field intensity measurement approach based on frequency shift with a high gain and a wide frequency range. We used two different frequency shift methods, i.e., stimulated Brillouin scattering and down-conversion. Based on the former method, an amplification module is designed to enhance the OES signal with a frequency range from 11 GHz to 20 GHz and a noise-suppressed gain of up to 63 dB, and based on the latter one, the high-frequency OES signal is down-converted to a sub-MHz intermediate frequency signal. The frequency shift approach shows the potential to detect and analyze high-frequency electric fields with low cost and a small footprint, which is valuable for their applications in electronic warfare, high-voltage engineering, space exploration, etc.

Low-Profile Lightweight Slot Array With Solar Cells for 5.8 GHz Band

A 4×4 slot array antenna with solar cells is presented for the 5.8 GHz band with a light weight and low profile of 0.039λ (λ is 5.8 GHz wavelength in the air). Coplanar waveguide excitation and foam substrate are adopted for a compact and lightweight structure. The measured impedance matching band is from 5.3 GHz to 6 GHz. The gain range is from 13.7 dBi to 16.3 dBi within the pass band. A tested peak gain of 14.8 dBi is achieved for the target band from 5.725 GHz to 5.85 GHz with unidirectional pattern. The solar cells can cover 72.5% of the total area with an enhanced capacity for photovoltaic power generation.

A Variable-Mode Bidirectional Isolated Power Converter for Wide Voltage-Transfer Ratio Applications

Lithium battery charging require a wide voltage gain range. Due to the limited voltage gain range of LLC converter, it is limited in battery storage application scenarios. In this paper, A interleaved parallel LLC converter is proposed to realize the charging and discharging processes of bidirectional battery energy storage systems. The converter extended range of voltage gain required for battery recovery area by mode switching control. For the interleaved parallel mode power equalization problem, a gain compensation control strategy is proposed to solve the power equalization problem of the converter in this mode. This results in more uniform thermal and current stresses on the charger, as well as smaller input and output ripple. Moreover, with the proposed variable-mode control strategy, the efficiency of the charging process remains above 90%. A 1.5-kW experimental platform was developed to validate the performance of the proposed converter.

Hybrid-Type DAB Converter With DC Blocking Capacitor for Ultrawide Input-Voltage Range

In this letter, a hybrid-type dual active bridge topology with dc blocking capacitor for ultra-wide input voltage is proposed. The proposed topology can expand the gain range by introducing voltage offset across the dc blocking capacitor, and has the ability to operate in single-stage or two-stage mode. The control strategy is also designed, which adopts the minimum resistive loss under the premise of soft switching as the optimization object to derive the operating boundary of the optimal modes. The proposed methodology avoids the additional loss caused by the increased devices of the traditional two-stage converters, and also avoids the efficiency dip of traditional converters with dc blocking capacitor at non-optimal voltage matching points. The performance of the proposed scheme is verified by experimental results.

An Intuitive and Noniterative Design Methodology for CLLC Chargers Employing Simplified Operation Modes Model

This paper mainly focuses on the simplified operation modes (SOM) model and resonant parameter design for the CLLC charger. Based on the mathematical and detailed operation waveform assumptions, the voltage gain model expressions and the operation mode boundaries are calculated directly, providing the high efficiency and high reliability of the CLLC converter. The proposed SOM model is more accurate in depicting the voltage gain compared with the conventional fundamental harmonic approximation (FHA) model. Moreover, the SOM model is more intuitive and has less computational complexity than the complicated and unsolvable time-domain model. As for the parameter design process, the inductance ratio <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k$</tex-math></inline-formula> and characteristic impedance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$Z_{0}$</tex-math></inline-formula> are selected instead of specific inductances and capacitances. Relying on the SOM model, a step-by-step parameter design methodology is studied, which avoids repetitive iterations and streamlines the procedure. The voltage gain range, efficiency, soft-switching operation, mode boundaries, and system stability are considered comprehensively and realized in this process. The simulations and experiments validate that the proposed SOM model is accurate, and the design methodology is straightforward through a 1-kW CLLC charger prototype with 97% peak efficiency.