Ultrahigh Gain Research Articles

An Enhanced Ultra-High Gain Active-Switched Quasi Z-Source Inverter

This paper proposes an enhanced ultra-high gain quasi Z-source inverter (EUHG-qZSI) having single unit of active switched capacitive network and switched inductor respectively. This inverter provides very high voltage gain profile with limiting value of shoot-through duty ratio of 0.186 and also, numerator factor of its gain is two times of (1+shoot-through duty ratio). Thus, the suggested inverter achieves higher voltage gain than the existing ultra-high/high gain/two-switched topologies. The voltage stresses on switches and capacitors of the proposed inverter are reduced. It also retains desirable qualities such as common ground with input DC supply and continuous source-side current for providing relief from current stress on input supply. The steady-state voltage gain, parameter values, current and voltage stresses of its components, loss and input current ripple are given to analyze the operation and characteristics of proposed inverter. The comparative voltage gains, voltage stresses and average switching device power are given to indicate its decent performances. Observations of both simulation and experimental verifications indicate real-time working of the suggested inverter.

Avalanche Photodiodes With Dual Multiplication Layers and Ultra-High Responsivity-Bandwidth Products for FMCW Lidar System Applications

In this work, we demonstrate a novel In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.52</sub> Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.48</sub> As based top-illuminated avalanche photodiode (APD), designed to circumvent the problem of serious bandwidth degradation under high gain (>100) and high power operation and significantly enhance the dynamic range in the established frequency modulated continuous wave (FMCW) lidar system. In our APD design, the carriers transiting through the dual multiplication (M-)layers are subjected to a stepped-up electric field profile, so they can be energized by the first step and propagate to the second step to trigger the avalanche processes. Such a cascade avalanche process leads to an ultra-high gain bandwidth product (460 GHz) with a 1 A/W responsivity at unit gain. Compared to the high-performance and commercial p-i-n PD and photo-receiver (PD + trans-impedance amplifier (TIA)) installed in the same lidar test bed, our demonstrated APD receiver (without TIA) has a larger S/N ratio under high operation gain (33 A/W) with less optical local-oscillator (LO) power required (0.25 vs. 0.5 mW), while exhibiting a wider dynamic range in each pixel. These advantages in turn lead to the construction of a better quality of 3-D lidar image by using the demonstrated APD.

Deep ultraviolet spectra from BGaN quantum dot structures

This work theoretically studies boron-containing ternary and quaternary lattice-matched quantum dot (QD) structures that emit ultraviolet (UV) wavelength by varying the boron mole fraction in the QD active region or the barrier. For BGaN and BAlGaN QD structures, matching to AlN, BAlN, AlGaN barriers and also BInGaN/AlN, the wide-bandgap AlN barrier imposes them to emit at 198–202 nm wavelength. For BInGaN QDs matching to the AlGaN, BAlN, the situation is different. They can emit at the range 252−291nm depending on the barrier and the efficiency of boron content in the barrier in redshifting the wavelength is deduced. The TE and TM gain and spontaneous emission spectra are high and increase under increasing boron in the active region or reducing boron content in the barrier region, exceeding its quantum-well counterpart and of central importance in light-emitting diode applications. Ultra-high gain is obtained from BInGaN/BAlN structure. Gain values are arranged according to the bandgap difference (ΔEg). The range of ΔEg is extended, in the studied structures, to ΔEg=1866−2856 meV, which is of practical importance in UV device applications. The total polarization is decreasing for the Al-containing systems, which is preferred.

Single-Switch Resonant Soft-Switching Ultra-High Gain DC-DC Converter With Continuous Input Current

An ultra-high gain DC-DC converter with single-switch structure is introduced in this paper. Full soft-witching is provided by simultaneous use of quasi-resonant performance of one resonant tank and leakage inductance of a three-winding coupled inductor (CI). Adopting the secondary and tertiary windings of the CI in separated voltage multiplier cells enables the converter to provide ultra-high voltage gain. The reverse recovery problem is resolved thanks to the quasi zero current switching performance of nearly all diodes, especially output diode because of the second resonant tank, so the total electromagnetic interference is significantly reduced. Continuous input current with low ripple expands the application of the proposed converter, especially in renewable energy applications. Steady-state performance and design considerations of the introduced converter are analyzed thoroughly and compared with recently introduced converters to establish its merits. Experimental results of a 200 W prototype are given to validate its analysis and performance.

A Near-Infrared CMOS Silicon Avalanche Photodetector with Ultra-Low Temperature Coefficient of Breakdown Voltage.

Silicon avalanche photodetector (APD) plays a very important role in near-infrared light detection due to its linear controllable gain and attractive manufacturing cost. In this paper, a silicon APD with punch-through structure is designed and fabricated by standard 0.5 μm complementary metal oxide semiconductor (CMOS) technology. The proposed structure eliminates the requirements for wafer-thinning and the double-side metallization process by most commercial Si APD products. The fabricated device shows very low level dark current of several tens Picoamperes and ultra-high multiplication gain of ~4600 at near-infrared wavelength. The ultra-low extracted temperature coefficient of the breakdown voltage is 0.077 V/K. The high performance provides a promising solution for near-infrared weak light detection.

A single‐switch high‐gain DC–DC converter for photovoltaic applications

AbstractThis article presents a high‐gain DC–DC converter consisting of a quadratic boost converter and a voltage multiplier, which helps to lift up the voltage gain. The gain will be further enhanced by increasing the turn's ratio of the coupled inductor. The key features include ultrahigh gain, low voltage stress across switching devices, low input current ripple, and hence, it is preferably suitable for renewable energy applications. A passive clamp lowers the voltage stress across MOSFET, so allowing switch with lower Rds(on) reduces the system cost. Besides this, input inductor makes current continuous and reduces input current ripple. The reverse recovery problem of diodes also gets diminished with the usage of leakage energy of the coupled inductor. The operating principle with different modes of operation is also explained. Zero current switching (ZCS) turn‐on is achieved for power switch, and ZCS turn‐off is achieved for diodes, which helps to reduce the switching losses. This improves the overall system efficiency. A 250‐W prototype is built up to validate the converter.

Gate tunable photoresponse of a two-dimensional p-n junction for high performance broadband photodetector

Optoelectronic devices based on two-dimensional (2D) van der Waals (vdWs) materials and their heterostructures are promising owing to their intriguing properties. However, the achievement of high-performance photodetectors over a wide detection range is still limited. In particular, detection in the near-infrared (NIR) region has not been attained successfully because of the relatively low responsivity to date. Herein, we report an efficient photodetection from visible to NIR ranges using a ReS2/Te vdWs heterostructure. The dependence of the photocurrent on the incident power reveals that the dominant operating mechanism can be switched between the photogating effect and photoconductive effect by applying the back-gate voltage. The ReS2/Te photodetector exhibits remarkable responsivities of 3 × 106 A W‒1 at 458 nm and 1 × 106 A W‒1 at 1062 nm laser irradiations, and an ultrahigh photoconductive gain (up to ∼108) resulting from the strong photogating effect. These outstanding performances demonstrate that the ReS2/Te vdWs heterostructure is suitable for high-performance broadband photodetectors in practical applications.

Predictive control strategy on an the ultra-high gain DC/DC converter suitable for photovoltaic energy conversion system

Abstract This paper presents a control scheme based on the predictive control strategy on an ultra-high gain DC/DC converter with two-phase interleaved structure. the proposed converter consists of coupled inductors and a voltage multiplier cell to increase the voltage gain. due to the variations in the input voltage and the load in the photovoltaic system, tracking the input voltage from its reference value and also dividing the current evenly in the interleaved structure are considered as important control objectives. the proposed predictive control scheme is employed to the proposed converter using two internal and external control loops and the use of a second-order luenberger observer. finally, the effectiveness and the desired performance of the proposed predictive control scheme is verified by presenting the simulation results as the real-time validation by MATLAB and ATMEGA16A-PU.

Full Soft-Switching Ultra-High Gain DC/DC Converter Using Three-Winding Coupled-Inductor with Modular Scalability for Renewable Energy Applications

This paper proposes a new non-isolated single-switch DC/DC converter with an ultra-high voltage gain, low input current ripple, low voltage stress, soft-switching operation, and modular scalability for renewable sources applications. Here, with the help of a Three-Winding Coupled-Inductor (TWCI) and Voltage Multipliers circuits, ultra-high voltage gains can be achieved without needing a large duty cycle. A regenerative clamp capacitor recycles the energy stored in the leakage inductor; thus, the maximum voltage across the single power switch is restricted. Moreover, at the turn-on instant of the power switch, a Zero Current Switching (ZCS) condition is achieved. By designing a resonant tank, the switched current value of the main switch at the turn-off instant is reduced significantly. Also, the leakage inductor of the TWCI helps all converter diodes to operate under the ZCS condition. Due to full soft-switching performance, the introduced topology can provide a wide output voltage range under a high conversion efficiency. The steady-state analysis and comprehensive comparisons are provided in this paper. A 160 W prototype with 24 V input and 250 V output voltage is developed to validate the theoretical analysis. Due to ZCS operation and low voltage stress (VDS ≈ 40 V), the power loss portion of the MOSFET is low. Moreover, the maximum voltage stresses of the diodes are measured 40 V, 60 V, 90 V, and 110 V that are well below the output voltage. Furthermore, at the full-load condition, the input current ripple is about 20 % and the measured efficiency is about 96.3%.

High Gain DC-DC Converter Integrating Dickson Charge Pump with Coupled Inductor Technique

In this paper, a novel high voltage gain DC-DC converter based on coupled inductor and voltage multiplier technique is proposed. The benefits of the proposed converter are ultra-high voltage gain, low voltage stress across the power switch and very low input current ripple by employing a low current ripple structure (LCR) at the input side. A low on state resistance (RDS(on)) of the power switch can be employed since the voltage stress is a maximum of 25% of the output voltage and the conduction losses of the switch is also reduced. Design of a 1.9kW, 48V at the low voltage side and 430V at the high voltage side is done and verified by simulation. Simulation results show an efficiency of over 93% when operating in continuous conduction mode (CCM).

Critical Behavior in Au Nanoparticle Arrays: Implications for All-Metal Field Effect Transistors with Ultra-high Gain at Room Temperature

Critical Behavior in Au Nanoparticle Arrays: Implications for All-Metal Field Effect Transistors with Ultra-high Gain at Room Temperature

New Opportunities for High-Performance Source-Gated Transistors Using Unconventional Materials.

Source‐gated transistors (SGTs), which are typically realized by introducing a source barrier in staggered thin‐film transistors (TFTs), exhibit many advantages over conventional TFTs, including ultrahigh gain, lower power consumption, higher bias stress stability, immunity to short‐channel effects, and greater tolerance to geometric variations. These properties make SGTs promising candidates for readily fabricated displays, biomedical sensors, and wearable electronics for the Internet of Things, where low power dissipation, high performance, and efficient, low‐cost manufacturability are essential. In this review, the general aspects of SGT structure, fabrication, and operation mechanisms are first discussed, followed by a detailed property comparison with conventional TFTs. Next, advances in high‐performance SGTs based on silicon are first discussed, followed by recent advances in emerging metal oxides, organic semiconductors, and 2D materials, which are individually discussed, followed by promising applications that can be uniquely realized by SGTs and their circuitry. Lastly, this review concludes with challenges and outlook overview.

Single-photon detection in the mid-infrared up to 10 μm wavelength using tungsten silicide superconducting nanowire detectors.

We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm. These detectors are promising for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet spectroscopy.

Avalanche Photodiodes with Dual Multiplication Layers for High-Speed and Wide Dynamic Range Performances

In this work, we demonstrate In0.52Al0.48As top/backside-illuminated avalanche photodiodes (APD) with dual multiplication layers for high-speed and wide dynamic range performances. Our fabricated top-illuminated APDs, with a partially depleted p-type In0.53Ga0.47As absorber layer and thin In0.52Al0.48As dual multiplication (M-) layer (60 and 88 nm), exhibit a wide optical-to-electrical bandwidth (16 GHz) with high responsivity (2.5 A/W) under strong light illumination (around 1 mW). The measured bias dependent 3-dB O-E bandwidth was pinned at 16 GHz without any serious degradation near the saturation current output. To further increase the speed, we downscaled the active diameter and adopted a back-side illuminated structure with flip-chip bonding for batter optical alignment tolerance. A significant improvement in maximum bandwidth was demonstrated (25 versus 18 GHz). On the other hand, we adopted a thick dual M-layer (200 and 300 nm) and 2 μm absorber layer in the APD design to circumvent the problem of serious bandwidth degradation under high gain (&gt;100) and high-power operation which significantly enhanced the dynamic range. Due to dual M-layer, the carriers could be energized in the first M-layer then propagate to the second M-layer to trigger the avalanche process. In both cases, despite variation in thickness of the absorber and M-layer, the cascade avalanche process leads to values close to the ultra-high gain bandwidth product (GBP) of around 460 GHz with a responsivity of 0.4 and 1 A/W at unit gain for the thin and thick M-layer devices, respectively. We successfully achieved a good sensitivity of around −20.6 dBm optical modulation amplitude (OMA) at a data rate of 25.78 Gb/s, by packaging the fabricated APDs (thin dual M-layer (60 and 88 nm) version) with a 25 Gb/s trans-impedance amplifier in a 100 Gb/s ROSA package. The results show that, the incorporation of a dual multiplication (M) layer structure in the APD opens a new window to obtaining the higher GBP in order to meet the requirements for high-speed transmission without the need of further downscaling the multiplication layer.

Inverting logic-in-memory cells comprising silicon nanowire feedback field-effect transistors

In this paper, we propose inverting logic-in-memory (LIM) cells comprising silicon nanowire feedback field-effect transistors with steep switching and holding characteristics. The timing diagrams of the proposed inverting LIM cells under dynamic and static conditions are investigated via mixed-mode technology computer-aided design simulation to verify the performance. The inverting LIM cells have an operating speed of the order of nanoseconds, an ultra-high voltage gain, and a longer retention time than that of conventional dynamic random access memory. The disturbance characteristics of half-selected cells within an inverting LIM array confirm the appropriate functioning of the random access memory array.

Ultrahigh Green and Red Optical Gain Cross Sections from Solutions of Colloidal Quantum Well Heterostructures.

We demonstrate amplified spontaneous emission (ASE) in solution with ultralow thresholds of 30 μJ/cm2 in red and of 44 μJ/cm2 in green from engineered colloidal quantum well (CQW) heterostructures. For this purpose, CdSe/CdS core/crown CQWs, designed to hit the green region, and CdSe/CdS@CdxZn1-xS core/crown@gradient-alloyed shell CQWs, further tuned to reach the red region by shell alloying, were employed to achieve high-performance ASE in the visible range. The net modal gain of these CQWs reaches 530 cm-1 for the green and 201 cm-1 for the red, 2-3 orders of magnitude larger than those of colloidal quantum dots (QDs) in solution. To explain the root cause for ultrahigh gain coefficient in solution, we show for the first time that the gain cross sections of these CQWs is ≥3.3 × 10-14 cm2 in the green and ≥1.3 × 10-14 cm2 in the red, which are two orders of magnitude larger compared to those of CQDs.

Hidden Vacancy Benefit in Monolayer 2D Semiconductors

Monolayer 2D semiconductors (e.g., MoS2 ) are of considerable interest for atomically thin transistors but generally limited by insufficient carrier mobility or driving current. Minimizing the lattice defects in 2D semiconductors represents a common strategy to improve their electronic properties, but has met with limited success to date. Herein, a hidden benefit of the atomic vacancies in monolayer 2D semiconductors to push their performance limit is reported. By purposely tailoring the sulfur vacancies (SVs) to an optimum density of 4.7% in monolayer MoS2 , an unusual mobility enhancement is obtained and a record-high carrier mobility (>115 cm2 V-1 s-1 ) is achieved, realizing monolayer MoS2 transistors with an exceptional current density (>0.60mA µm-1 ) and a record-high on/off ratio >1010 ,and enabling a logic inverter with an ultrahigh voltage gain >100.The systematic transport studies reveal that the counterintuitive vacancy-enhanced transport originates from a nearest-neighbor hopping conduction model, in which an optimum SV density is essential for maximizing the charge hopping probability. Lastly, the vacancy benefit into other monolayer 2D semiconductors is further generalized; thus, a general strategy for tailoring the charge transport properties of monolayer materials is defined.

Ultrahigh Voltage Gain DC–DC Boost Converter With ZVS Switching Realization and Coupled Inductor Extendable Voltage Multiplier Cell Techniques

In this article, a novel ultrahigh voltage gain dc–dc boost converter with expandable diode-capacitor voltage multiplier (VM) cells is presented. The diode-capacitor VM cells and coupled inductors are employed in the presented topology to provide a higher voltage gain. Also, the main and the auxiliary power switches of the presented converter operate with zero voltage switching. The coupled inductors' leakage inductances control the rates of the current drop in the voltage multiplier diodes, which decreases their reverse recovery losses markedly. Moreover, the voltage stresses on all capacitors and semiconductors are reduced significantly. In this converter, the number of voltage multiplier cells, and the coupled inductors turn ratios provide three degrees of design freedom. These degrees of freedom are used to set the desired voltage stresses of the semiconductors within the desired range and to provide a high voltage gain at optimum duty cycles. The design and theoretical analysis of the presented converter are discussed. Finally, the performance of the presented converter is validated using a 500 W, 40 V/380 V laboratory prototype converter, and the experimental results confirm the theoretical calculation.

A New Transformerless Ultra High Gain DC–DC Converter for DC Microgrid Application

High gain dc-dc converters are used in several applications which include solar photovoltaic system, switch-mode power supplies and fuel cells. In this paper, an ultra-high gain dc-dc boost converter is proposed and analyzed in detail. The converter has a gain of six times as compared with the boost converter. The high gain is achieved by utilizing switched inductors and switched capacitors. A modified voltage multiplier cell (VMC) with switched inductors is proposed. The converter has a single switch which makes its operation easy. Moreover, the voltage across the switch, diodes and capacitors are less than the output voltage which increases the overall efficiency of the converter. The converter performance in steady-state is analyzed in detail and it is compared with other latest high gain converters. The working of the converter in non-ideal conditions is also discussed in detail. The loss analysis is done using PLECS software by incorporating the real models of switches and diodes from the datasheet. To confirm and validate the working of the proposed converter a hardware prototype of 200 W is developed in the laboratory. The converter achieves high gain at low duty ratios and its performance is found to be good in open and closed loop conditions.

New Single‐Switch quadratic boost DC/DC converter with Low voltage stress for renewable energy applications

In this paper, a novel non-isolated Single-Switch Quadratic Boost Coupled-Inductor (SSQBCI) DC/DC converter with continuous input current and low voltage stress on the switching component is presented. The suggested structure is based on the traditional quadratic boost converter. In this new topology, to achieve an ultra-high voltage gain without large duty cycle, a Coupled-Inductor (CI) along with a Voltage Multiplier (VM) are employed. The magnetic energy stored in the leakage inductor of the CI is recycled by a regenerative passive clamp capacitor that is connected with the switch in parallel, which helps to limit the maximum voltage across the switch. Therefore, to reduce the switch conduction loss and improve the efficiency, a switch with the low static drain-to-source ON-resistance can be used. Moreover, the low voltage stress on the output side diode alleviates the reverse recovery loss. The steady-state operating principle, comparisons with other related topologies and also design considerations in Continuous Conduction Mode (CCM) will be analyzed in detail. Finally, the performance of the proposed SSQBCI is verified by experimental results using a prototype with 30V input and 200V - 160 W output operation at a constant switching frequency 50 kHz.