This paper presents the design of an ultra-low power, fully differential operational amplifier with programmable differential gain, optimized for low-frequency applications. Designed in planar 0.18 µm CMOS technology, the amplifier offers four distinct gain levels between 6 dB and 16.5 dB. A novel approach ensures robust temperature compensation, limiting average gain variation to 50 mdB/ ◦C over a temperature range from –10 ◦C to 90 ◦C range. Furthermore, the design achieves an impressive average line sensitivity of 0.017%/ V across 0.4 V to 5 V supply variations. High linearity is maintained with <%1 distortion for input signals ranging from 600 nV p . p to 55 mV p . p , yielding a dynamic range of approximately 75 dB.The circuit exhibits an offset voltage < 200 nV while consuming a maximum power of 180 nW, occupying a silicon area of 0.86 mm 2. All results, including the impact of parasitic elements and process variations, are validated post-layout. This amplifier is primarily intended as an additional programmable gain stage complementing a fixed-gain pre-amplifier in various low frequency applications.

Based on three-channel phase-shift voltage regulation, this paper proposes a control strategy for underwater wireless charging systems in order to address efficiency degradation and weak misalignment tolerance during wide voltage gain output. The strategy designs a novel spatially decoupled three-channel coupling mechanism and constructs a distributed half-bridge topology, where three independent power transmission channels are generated by controlling three transmitting coils via half-bridge circuits. The strategy is able to switch system operation modes and adjust phase-shift angles between channels, so that output voltage can be regulated flexibly within a broad range, and zero phase angle (ZPA) operation for voltage and current can be maintained in each power transmission channel to improve power transfer efficiency. As demonstrated by the simulation and experimental results, the control strategy exhibits strong wide voltage gain regulation, misalignment tolerance, and fault tolerance capabilities.

In solidly grounded bipolar high-voltage direct current (HVDC) grids, DC faults can cause rapid current surges due to the inherent coupling between poles, posing significant risks to system stability. Traditional traveling-wave protection methods, while unaffected by MMC control characteristics, face challenges in bipolar systems where pole-to-pole coupling complicates fault identification and necessitates extensive deployment of costly DC circuit breakers (DCCBs). To address these limitations, this paper proposes a hybrid MMC topology based on an improved dual half-bridge submodule (IDHSM) with self-clearing capability and coordinated control-protection (CCP) strategy. The IDHSM enables dynamic adjustment of activated submodule ratios through adaptive modulation coefficient, actively reducing DC voltage by 14.93% under 300-Ω fault resistance while maintaining arm current constraints. Compared with full bridge submodule (FBSM), this hybrid topology reduces IGBT counts per voltage level by 50%, lowering hardware costs. Due to its dual capacitor structure with a passive current path, IDHSM can block energy injection from the AC side during faults. According to the simulations on ±500 kV four-terminal HVDC grid, fault identification within 1 ms using modulus instantaneous average values, resolving protection sensitivity degradation caused by MMC-based current limiting. In addition, 30% reduction in DCCB breaking current (from 7.0 kA to 4.9 kA) through coordinated current limiting. The proposed strategy exhibits strong performance within the transition resistance range of 0.1-300 Ω.

The brushless dc motor (BLDCM) drive is suffering from current/torque ripples. The DC-DC converter based BLDCM drive topology is widely preferred to suppress ripples. The improved characteristics such as low mechanical oscillation and stiff-speed regulation of BLDCM further introduces undamped AC signal which results destabilization of DC-link power (DCLP) supply. The different breeds of filter techniques have been recommended to stabilize the DCLP supply. However, the recommended filters are composed on the basic of concept of low pass filter (LPF) or band pass filter (BPF). In addition, these filters requires a precise association with active atonement, current reference and nonlinear interaction. In this context, a notch-filter (NF) has applied to stabilize the DCLP supply. The NF is investigated for a super-lift-Luo (SLL) converter assist BLDCM drive. The SLL converter is employed to suppress commutation current ripple (CCR) whereas the NF is applied to draw stabilized DCLP supply. A hardware prototype is developed and results are given to confirm the effectiveness of the proposed stabilization strategy and design. Thus, the suggested compensation technique effectively stabilized the DCLP supply of SLL converter employed to CCR mitigation in the BLDCM drive.

In wireless power transfer (WPT) systems, lateral misalignment between coils can lead to substantial fluctuations in transmission efficiency. Although various misalignment-tolerant coil structures have been proposed, many still face challenges in maintaining high transmission efficiency under displacement conditions. To overcome these limitations, this paper propose a novel interwoven magnetic field (IMF) coil structure that simultaneously achieves strong magnetic coupling and enhanced misalignment tolerance. The proposed IMF structure partitions the transmitting coil into two functional components: a primary transmitting coil configured as a Double-D (DD) coil, and auxiliary compensating coils implemented as bipolar (BP) coils symmetrically placed on both sides of the DD coil. The receiving side employs a reverse-series connection coil configuration. The IMF structure benefits from the inherently high coupling efficiency of DD coils relative to conventional single coils for the same footprint, while the BP coils provide edge compensation. This configuration enables the system to sustain high efficiency even under coil displacement. Specifically, when lateral misalignment occurs along the direction of vehicle motion, the magnetic interaction between the reverse-series receiving coil and the edge-positioned BP coils adaptively compensates for the misalignment, thereby preserving the stability of the system of transmission efficiency. Under a horizontal misalignment along the Y-axis corresponding to 50% of the transmitter coil length (394 mm), the IMF system exhibits a maximum transmission efficiency fluctuation rate of only 0.21%, while achieving a peak efficiency of 97.16%.

Water electrolysis is considered one of the most promising methods for hydrogen production using renewable energy sources (RES). In megawatt (MW)-level hydrogen production systems, a MW-level hydrogen converter is essential for interfacing the medium-voltage DC bus (MVDCB) with the electrolyzer. This paper proposes a novel hydrogen converter that incorporates a combined Input Series Output Parallel (ISOP) configuration, which offers several advantages, including a simplified topology, high voltage ratio, high energy efficiency, low output current ripple, and enhanced reliability. The design of the proposed hydrogen converter emphasizes the optimization of the snubber circuit, which plays a critical role in ensuring safe operation. To guide the design process, the Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is employed. Furthermore, an accurate model of the proposed hydrogen converter is developed to facilitate controller design, enabling power balance among the modules of this combined topology. This step is crucial to maintaining the stable operation of the hydrogen converter. Finally, experimental results are presented to validate the effectiveness of the snubber circuit design and the control strategy for the proposed hydrogen converter.

The five basic step-up switched-capacitor converter (SCC) topologies, namely, ladder, Dickson, series-parallel, Fibonacci and voltage doubler, have limited voltage regulation ranges, 3000with their maximum voltage gains predetermined by the circuit configurations. In this paper, a family of hybrid boost DC-DC converters based on these five basic SCCs is derived by replacing an active switch with a filter inductor. Compared to the basic SCCs, the proposed converters feature higher step-up voltage gain, wider output voltage-gain variation ranges, and fewer components, making them suitable for 48 V to 240 V step-up applications in datacenter power supplies. Furthermore, some of the proposed topologies achieve higher power density than conventional boost converters, aided by the switched capacitors, making them suitable for integration and miniaturization. A quantitative comparison of the volume of passive components between the proposed hybrid SCCs and conventional boost converters is provided. Finally, a 40–60 V to 240 V prototype is designed and tested to verify the analysis.

Aiming at the contradiction between the narrow switching frequency operating range and the wide output voltage range of the traditional LLC resonant converter, a three-switch LLC resonant converter with a variable structure type and wide output voltage range and its control method are proposed. The converter adopts three switching tubes in the primary inverter circuit, which can realise the independent or joint operation of two transformers. Four different operating modes can be realised by controlling the ON and OFF of the primary-side switching tubes and the secondary-side auxiliary switches, which shortens the operating range of the switching frequency and widens the voltage gain range, and meets the requirements of wide output voltage range applications. Since the converter always works in the weak inductive region, it can achieve zero-voltage turn-on of the primary switch and zero-current turn-off of the secondary diode over the whole range, which has good soft-switching performance. This paper analyses the working principle, voltage characteristics and parameter design of the converter. Finally, a 1kW experimental prototype is fabricated based on the operating principle of the converter, and the experimental results show that the converter meets the requirements of wide output voltage range applications in all aspects.

Configuring half-bridge circuits with CRC or RC circuits at both ends of the bus, RC circuits at both ends of the device, and in conjunction with reduced loop inductance is a typical solution to address half-bridge switching oscillations and voltage overshoots, and to optimize electromagnetic interference (EMI) characteristics. However, this scheme still has the problems of poor damping effect, high degree of overvoltage, and high turn-on loss. In this paper, we remove the switch-by-switch RC circuit to reduce extra losses, actively increase the inductance of the feeder circuit to achieve zero current turn-on, and design a DC(VS)-RC absorption topology with energy return circuits at both ends of the bus. The designed topology absorbs the overvoltage energy stored in the inductor of the switching converter and feeds it back to the bus to reduce the overvoltage and improve efficiency. Experimental studies and comprehensive comparative studies verify the effectiveness of the proposed scheme. The experimental results show that DC(VS)-RC with increasing loop inductance has good overvoltage and oscillation suppression performance and can significantly reduce the switching losses.

To settle the voltage-loop PI controller of flux weakening (FW) control causes large oscillations at deeper FW regions, A deep FW control method for the voltage loop of the feedback super-twisting sliding mode controller (FSTSMC) compensated by the fast sliding mode disturbance observer (FSMDO) is proposed. Firstly, a hyperlocal model of the voltage ring in the complex environment is constructed. On this basis, FSTSMC based on the feedback super-helix algorithm is designed, which can effectively suppress the jitter of the system in the FW control region. Then, the FSMDO is designed to observe the disturbances in the voltage loop and feed the results to the FSTSMC. It improves the stability of the system in FW regions. Finally, the method is compared with PI and STSMC, which proves the method has better steady-state performance and anti-interference ability in the deep FW region.

An all-digital calibration technique for time-interleaved ADC(TIADC) timing mismatch is proposed in this paper. The calibration technique is based on a direction correction-based technique for TIADCs. The proposed method uses Least Mean Squares (LMS) Iteration to gradually estimate and the compensation algorithmfocuses on third-order Tayler series expansion. Different from conventional calibration architecture, the proposed method introduces a corrective technique addressing calibration direction, which may be wrong when the frequency of the input signal does not satisfy the Nyquist sampling theorem of the sub-ADC. The bandwidth of the input signal stands to be broadened when integrated with the proposed calibration algorithm.

The double-line frequency ripple power exists inherently in single-phase power converters. To address this problem, active power decoupling technique (APD) is widely used. It diverts the ripple power into a small energy storage element through introducing passive and active power devices. This inevitably involves more voltage and current sensors for corresponding control, which raises the cost while decreasing reliability and power density. In this paper, a Lyapunov-based methodology is proposed to achieve APD control without adding any sensor. According to the designed controller laws, the practical decoupling capacitor voltage will converge to its reference. The decoupling voltage reference is given by taking into account buffering the double-line frequency ripple power. Afterwards, the robustness against parameter perturbations of the proposed method is discussed. Finally, the experimental results verify the feasibility of the proposed control strategy.

The long transmission distance in wireless power transmission(WPT) system will lead to a sharp decline in transmission efficiency, this paper presents a novel ortho-octagonal double helix metamaterial that can effectively enhance the transmission efficiency of WPT systems, theoretically derived and experimentally verified the enhancement of evanescent wave transmission by this metamaterial dielectric plate. A WPT simulation system operating at 10.78 MHz is constructed by HFSS software, and the effects of adding passive relay coils and different shapes of metamaterials on the transmission efficiency are comparatively investigated. Both simulation and experimental results show that the transmission efficiency of the WPT system can be improved to different degrees after inserting different shapes of metamaterials at the transceiver end of the system. When the transceiver coil spacing of the WPT system is greater than 22 cm, the effect of metamaterials on the system transmission efficiency enhancement shows an increasing and then decreasing trend as the distance increases. The positive octagonal metamaterial improves 12% over the circular metamaterial in the mid-range transmission distance due to its better magnetic coupling effect. When the transceiver coil spacing is 22 cm, the open-circuit voltage of the receiving coil after loading the metamaterial is stabilized to be enhanced by nearly 5 times, and it has the best effect at 30 cm, and the transmission efficiency is enhanced from 30% to 60%, which verifies the effective enhancement of the metamaterial on the transmission efficiency of the WPT system.

This paper proposes a fully integrated low dropout (LDO) regulator with gate-couple flipped voltage follower(GC-FVF). The proposed GC-FVF addresses the limited output swing issue of conventional PMOS FVF in LDOs while maintaining a low output impedance. Besides, this LDO introduces a cascode compensation loop, which, along with the low output impedance of GC-FVF, pushes the output pole far away from the unity-gain bandwidth under both light and heavy load conditions. Consequently, the LDO becomes a stable two-pole system, supporting a high loop gain of up to 100dB and significantly enhancing the load and line regulation. Key specifications include a preset output voltage of 1.8V, a minimum unregulated input voltage of 2V, a maximum output current of 100mA, a ground current of 32μA, and an active chip area of 260μm×180μm. Notably, this LDO achieves high load regulation of 4.8μV/mA and high line regulation of 13.8μV/V without the need for off-chip capacitors.

Despite the performed progressive research work, the interpretation of negative group delay (NGD) function remains not familiar to non-specialist design and fabrication circuit engineers. The functionality misunderstanding limits the NGD circuit applications compared to other classical electronic functions. The present paper is dealing on the design of tunable property circuit by operating with positive and negative delay behaviors. The topology of the tunable circuit by using low-pass (LP) type NGD one is described. The design formulas for calculating the circuit resistor and capacitor parameters from the desired delay are expressed. The design feasibility of the tunable circuit composed of LP-NGD cell and RC-circuit is validated with a proof-of-concept (PoC) implemented on a test board. Two different signals with pulse and arbitrary waveforms having tens-milliseconds duration were considered during the validation tests. As expected by tuning a varistor from 0.4 kΩ to 1 kΩ, the negative delay behavior varying from about -0.4 ms was verified thanks to the time-advanced effect due to the LP-NGD property. Then, the output signal delay was observed to become positive when the varistor is tuned from 1 kΩ to 3 kΩ.

This paper presents the development of an interleaved bidirectional DC-DC converter with single-phase high-frequency isolation associated with two different pulse width modulations (PWM), one for each power flow direction. The converter stages analysis, DC voltage gains expressions, and voltage/current stresses in CCM are presented. The proposed converter advantages are new modulation, the current ripple frequency and voltage in two ports is four times higher than the switching frequency, volume and weight reduction of passive elements, and balanced current distribution between the legs. Besides, the single-phase transformer that provides galvanic isolation between the DC bus and the battery or supercapacitor. An experimental prototype is implemented in the laboratory to validate the mathematical and theoretical analysis for both energy flow senses under the test conditions at converter-rated power 2.5kW, Low voltage side 180V, and high voltage side 380V.

This paper introduces a new non-isolated double-input triple-output (DITO) high voltage gain DC-DC converter with a wide range of applications, including hybrid voltage source systems, solar home appliances, dc bus power distribution systems, and electrical vehicles (EV). The proposed DITO converter interfaces two hybrid voltage sources to supply three different output loads with varying voltage and power levels. Compared to conventional converters of the same type, the proposed DITO converter offers several advantages, including operation for all duty cycles, integration of hybrid energy sources to transfer power to multiple loads, high voltage conversion ratio for all three output ports, a higher ratio of total voltage gain to total components number, common grounded input and output DC ports, simultaneous DC voltage regulation of three output ports by tuning separate controlling parameters of duty cycles, an additional turn ratio of coupled inductors to increase the voltage gain of output ports, and medium voltage stress on switches. The proposed DITO converter utilizes a new single-switch single-coupled-inductor DC-DC structure, which is analyzed and verified through a prototype implementation for 25V and 30V input voltages and 210V, 330V, and 400V output voltages with a total power of 480W. The experimental results confirm the simulation results and theoretical analysis.

A document by Zisong Mo. Click on the document to view its contents.