A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achie...A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.展开更多
A nonlinear robust control strategy is proposed to force an underactuated surface ship to follow a predefined path with uncertain environmental disturbance and parameters.In the controller design,a high-gain observer ...A nonlinear robust control strategy is proposed to force an underactuated surface ship to follow a predefined path with uncertain environmental disturbance and parameters.In the controller design,a high-gain observer is used to estimate velocities,thus only position and yaw angle measurements are required.The control problem of underactuated system is transformed into a control of fully actuated system through adopting an improved line-of-sight(LOS) guidance law.A sliding-mode controller is designed to eliminate the yaw angle error,and provide the control system robustness.The control law is proved semi-globally exponentially stable(SGES) by applying Lyapunov stability theory,and numerical simulation using real data of a monohull ship illustrates the effectiveness and robustness of the proposed methodology.展开更多
In transportation cyber-physical-systems （T-CPS）, vehicle-to-vehicle （V2V） communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrast...In transportation cyber-physical-systems （T-CPS）, vehicle-to-vehicle （V2V） communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrastructures, and engine cylinder pressure is significant for engine diagnosis on-line and torque control within the information exchange process under V2V communications. However, the parametric uncertainties caused from measurement noise in T-CPS lead to the dynamic performance deterioration of the engine cylinder pressure estimation. Considering the high accuracy requirement under V2V communications, a high gain observer based on the engine dynamic model is designed to improve the accuracy of pressure estimation. Then, the analyses about convergence, converge speed and stability of the corresponding error model are conducted using the Laplace and Lyapunov method. Finally, results from combination of Simulink with GT- Power based numerical experiments and comparisons demonstrate the effectiveness of the proposed approach with respect to robustness and accuracy.展开更多
Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively...Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38%(4.05 GHz–5.95 GHz)and AR bandwidth of 24.9%(4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7%(3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.展开更多
Renewable electricity options, such as fuel cells, solar photovoltaic,and batteries, are being integrated, which has made DC micro-grids famous.For DC micro-grid systems, a multi input interleaved non-isolated dc-dcco...Renewable electricity options, such as fuel cells, solar photovoltaic,and batteries, are being integrated, which has made DC micro-grids famous.For DC micro-grid systems, a multi input interleaved non-isolated dc-dcconverter is suggested by the use of coupled inductor techniques. Since itcompensates for mismatches in photovoltaic devices and allows for separateand continuous power flow from these sources. The proposed converter hasthe benefits of high gain, a low ripple in the output voltage, minimal stressvoltage across the power semiconductor devices, a low ripple in inductorcurrent, high power density, and high efficiency. Soft-switching techniquesare used to realize that the reverse recovery issue of the diodes is moderated, the leakage energy is reused, and no new scheme is appropriated. Toreduce conduction losses, minimum voltage rating MOSFETs with a low ONresistance can be utilized. The converter can supply the required power fromthe load in the absence of one or two resources. Furthermore, due to the highgain of boosting voltage, the converter works in an Adaptive Neuro-FuzzyInference System (ANFIS). The operation principle, steady-state analysis ofthe proposed converter, is given and simulated utilizing MATLAB/Simulinksimulation software.展开更多
The defect-related photoconductivity gain and persistent photoconductivity(PPC)observed in Ga_(2)O_(3)Schottky photodetectors lead to a contradiction between high responsivity and fast recovery speed.In this work,a me...The defect-related photoconductivity gain and persistent photoconductivity(PPC)observed in Ga_(2)O_(3)Schottky photodetectors lead to a contradiction between high responsivity and fast recovery speed.In this work,a metal-semiconductor-metal(MSM)Schottky photodetector,a unidirectional Schottky photodetector,and a photoconductor were constructed on Ga_(2)O_(3)films.The MSM Schottky devices have high gain(>13)and high responsivity(>2.5 A/W)at 230-250 nm,as well as slow recovery speed caused by PPC.Interestingly,applying a positive pulse voltage to the reverse-biased Ga_(2)O_(3)/Au Schottky junction can effectively suppress the PPC in the photodetector,while maintaining high gain.The mechanisms of gain and PPC do not strictly follow the interface trap trapping holes or the self-trapped holes models,which is attributed to the correlation with ionized oxygen vacancies in the Schottky junction.The positive pulse voltage modulates the width of the Schottky junction to help quickly neutralize electrons and ionized oxygen vacancies.The realization of suppression PPC functions and the establishment of physical models will facilitate the realization of high responsivity and fast response Schottky devices.展开更多
This paper presents the design of wideband and high gainFrequency Selective Surface(FSS)loaded antenna for ultra-wideband(UWB)wireless applications requiring high-gain.The antenna consists of a monopole and an FSS ref...This paper presents the design of wideband and high gainFrequency Selective Surface(FSS)loaded antenna for ultra-wideband(UWB)wireless applications requiring high-gain.The antenna consists of a monopole and an FSS reflector.Initially,a conventional rectangular monopole antenna is modified using slot and stub to achieve wide operational bandwidth and size reduction.This modified antenna shows 50%miniaturization compared to a primary rectangular monopole,having a wide impedance bandwidth of 3.6-11.8 GHz.Afterward,an FSS is constructed by the combination of circular and square ring structures.The FSS array consisting of 8×8-unit cells are integrated with the antenna as a reflector to enhance the performance of the proposed miniaturized UWB antenna.The loading of FSS results in an improvement of at least 4 dBi gain in the entire operational bandwidth.Moreover,the antenna’s bandwidth is also increased at the lower frequency band due to the presence of the FSS.A prototype of the antenna is fabricated and tested to verify the simulation results.The simulation and measurement results show that the antenna offers a wideband-10 dB impedance bandwidth ranging from 2.55-13GHz with a stable peak gain of 8.6 dBi and retains the radiation pattern stability.展开更多
A 16 × 16 micro-strip antenna array with high gain characteristic was proposed for the 5.5 GHz W/MAX application. The T-junctions with a power ratio of 2 ： 1 were used to design the feed network. To correct the ...A 16 × 16 micro-strip antenna array with high gain characteristic was proposed for the 5.5 GHz W/MAX application. The T-junctions with a power ratio of 2 ： 1 were used to design the feed network. To correct the stepped discontinuity of impedance change in common multi-section impedance transformer, exponential line matching trans- formers were adopted in the WiMAX frequency band. The reflection coefficient was lower than - 15 dB from 5.08 GHz to 5.87 GHz. The measured gain of the antenna array achieved 29.8 dBi on E-plane at 5.8 GHz.展开更多
Renewable energy with sources such as photovoltaic(PV)or fuel cells can be utilized for the generation of elec-trical power.But these sources generate fewer voltage values and therefore require high gain converters to...Renewable energy with sources such as photovoltaic(PV)or fuel cells can be utilized for the generation of elec-trical power.But these sources generate fewer voltage values and therefore require high gain converters to match with DC bus voltage in microgrids.These high gain converters can be implemented with switched capacitors to meet the required DC bus voltage.Switched capacitors operate in a series and parallel combination during switch-ing operation and produce high static gain,limits reverse voltage that appears across the components.A novel converter is proposed that satisfies all the features such as high voltage gain,only one switch,forces less potential stress cross the components,ripple current is less.These features of the proposed converter are verified through MATLAB/SIMULINK.展开更多
In this paper, a directional antenna with high gain at low elevation is designed. The antenna uses 12-unit half-wave oscillators for array formation, the antenna voltage standing wave ratio is less than 1.4 in the fre...In this paper, a directional antenna with high gain at low elevation is designed. The antenna uses 12-unit half-wave oscillators for array formation, the antenna voltage standing wave ratio is less than 1.4 in the frequency band of 1400 MHz to 1550 MHz, the pitch surface wave beam range is 0°~40°and the minimum gain of the antenna is ≥ 10dBi in the pitch surface range of 0°~3°and the horizontal plane range ±60°.展开更多
A rectangular microstrip patch antenna using conventional Poly Tetra Fluride Ethelene (PTFE) substrate with air cavity is proposed and theoretically investigated. Considerably high gain along with improved front to ba...A rectangular microstrip patch antenna using conventional Poly Tetra Fluride Ethelene (PTFE) substrate with air cavity is proposed and theoretically investigated. Considerably high gain along with improved front to back radiation isolation is demonstrated using such proposed antenna. The radiation performance of this new antenna has been compared to a conventional microstrip patch for some commonly used aspect ratios (width to length ratio). Compared to conventional microstrip antenna the proposed configuration shows more than 12% increment in peak gain and more than 10% increment in front to back radiation performance in each set of aspect ratio. The elucidation of such improvement in the radiation characteristics of the proposed antenna is also presented.展开更多
In this paper, a wideband high gain millimeter wave radar array antenna based on a wavy power divider was proposed. The radar antenna comprises a wavy power divider and a 10-element array antenna. By adjusting the wav...In this paper, a wideband high gain millimeter wave radar array antenna based on a wavy power divider was proposed. The radar antenna comprises a wavy power divider and a 10-element array antenna. By adjusting the wavy radius of the power divider, the surface current of the power divider is altered, resulting in better impedance matching with the antenna. This ultimately leads to a significant improvement in bandwidth performance. The 4×10 millimeter wave radar antenna loaded with a wavy power divider exhibits an approximate enhancement of 3 GHz compared to traditional microstrip power divider antennas, and an average gain increase of 2.42 dB within the vehicle millimeter wave radar frequency band relative to the improved gradient power divider structure. The 4×10 millimeter wave radar antenna loaded with wavy power divider possesses the characteristics of high gain and broad bandwidth.展开更多
This study begins with the fabrication and simulation of high-performance back-illuminated AlGaN-based solar-blind ultraviolet(UV)photodetectors.Based on the photodetectors,a low-noise,high-gain UV detection system ci...This study begins with the fabrication and simulation of high-performance back-illuminated AlGaN-based solar-blind ultraviolet(UV)photodetectors.Based on the photodetectors,a low-noise,high-gain UV detection system circuit is designed and fabricated,enabling the detection,acquisition,and calibration of weak solar-blind UV signals.Experimental results demonstrate that under zero bias conditions,with a UV light power density of 3.45μW/cm^(2) at 260 nm,the sample achieves a peak responsivity(R)of 0.085 A·W^(−1),an external quantum efficiency(EQE)of 40.7%,and a detectivity(D^(*))of 7.46×10^(12) cm·Hz^(1/2)·W^(−1).The system exhibits a bandpass characteristic within the 240–280 nm wavelength range,coupled with a high signal-to-noise ratio(SNR)of 39.74 dB.展开更多
In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effec...In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.展开更多
A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically...A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.展开更多
As the front-end preamplifiers in optical receivers, transimpedance amplifiers （TIAs） are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time,...As the front-end preamplifiers in optical receivers, transimpedance amplifiers （TIAs） are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range （DR） to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.展开更多
A low power high gain differential UWB low noise amplifier （LNA） operating at 3-5 GHz is presented. A common gate input stage is used for wideband input matching; capacitor cross coupling （CCC） and current reuse t...A low power high gain differential UWB low noise amplifier （LNA） operating at 3-5 GHz is presented. A common gate input stage is used for wideband input matching; capacitor cross coupling （CCC） and current reuse techniques are combined to achieve high gain under low power consumption. The prototypes fabricated in 0.18-μm CMOS achieve a peak power gain of 17.5 dB with a -3 dB bandwidth of 2.8-5 GHz, a measured minimum noise figure （NF） of 3.35 dB and -12.6 dBm input-referred compression point at 5 GHz, while drawing 4,4 mA from a 1.8 V supply. The peak power gain is 14 dB under a 4.5 mW power consumption （3 mA from a 1.5 V supply）. The proposed differential LNA occupies an area of 1,01 mm^2 including test pads.展开更多
A low power high gain gain-controlled LNA ＋ mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. T...A low power high gain gain-controlled LNA ＋ mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNA ＋ mixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNA ＋ mixer, a previous low power LNA ＋ mixer, and the proposed LNA ＋ mixer are presented. The circuit is implemented in 0.18 #m mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2 and consumes 2 mA current under 1.8 V supply.展开更多
The development of fuel cell vehicles(FCVs)has a major impact on improving air quality and reducing other fossil-fuel-related problems.DC-DC boost converters with wide input voltage ranges and high gains are essential...The development of fuel cell vehicles(FCVs)has a major impact on improving air quality and reducing other fossil-fuel-related problems.DC-DC boost converters with wide input voltage ranges and high gains are essential to fuel cells and DC buses in the powertrains of FCVs,helping to improve the low voltage of fuel cells and“soft”output characteristics.To build DC-DC converters with the desired performance,their topologies have been widely investigated and optimized.Aiming to obtain the optimal design of wide input range and high-gain DC-DC boost converter topologies for FCVs,a review of the research status of DC-DC boost converters based on an impedance network is presented.Additionally,an evaluation system for DC-DC topologies for FCVs is constructed,providing a reference for designing wide input range and high-gain boost converters.The evaluation system uses eight indexes to comprehensively evaluate the performance of DC-DC boost converters for FCVs.On this basis,issues about DC-DC converters for FCVs are discussed,and future research directions are proposed.The main future research directions of DC-DC converter for FCVs include utilizing a DC-DC converter to realize online monitoring of the water content in FCs and designing buck-boost DC-DC converters suitable for high-power commercial FCVs.展开更多
文摘A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.
基金Projects(61004008,51509055)supported by the National Natural Science Foundation of ChinaProject(61422230302162223013)supported by the Laboratory of Science and Technology on Water Jet Propulsion,China
文摘A nonlinear robust control strategy is proposed to force an underactuated surface ship to follow a predefined path with uncertain environmental disturbance and parameters.In the controller design,a high-gain observer is used to estimate velocities,thus only position and yaw angle measurements are required.The control problem of underactuated system is transformed into a control of fully actuated system through adopting an improved line-of-sight(LOS) guidance law.A sliding-mode controller is designed to eliminate the yaw angle error,and provide the control system robustness.The control law is proved semi-globally exponentially stable(SGES) by applying Lyapunov stability theory,and numerical simulation using real data of a monohull ship illustrates the effectiveness and robustness of the proposed methodology.
基金supported by the National Natural Science Foundation of China(Grant No.61304197)the Scientific and Technological Talents of Chongqing,China(Grant No.cstc2014kjrc-qnrc30002)+2 种基金the Key Project of Application and Development of Chongqing,China(Grant No.cstc2014yykf B40001)the Natural Science Funds of Chongqing,China(Grant No.cstc2014jcyj A60003)the Doctoral Start-up Funds of Chongqing University of Posts and Telecommunications,China(Grant No.A2012-26)
文摘In transportation cyber-physical-systems （T-CPS）, vehicle-to-vehicle （V2V） communications play an important role in the coordination between individual vehicles as well as between vehicles and the roadside infrastructures, and engine cylinder pressure is significant for engine diagnosis on-line and torque control within the information exchange process under V2V communications. However, the parametric uncertainties caused from measurement noise in T-CPS lead to the dynamic performance deterioration of the engine cylinder pressure estimation. Considering the high accuracy requirement under V2V communications, a high gain observer based on the engine dynamic model is designed to improve the accuracy of pressure estimation. Then, the analyses about convergence, converge speed and stability of the corresponding error model are conducted using the Laplace and Lyapunov method. Finally, results from combination of Simulink with GT- Power based numerical experiments and comparisons demonstrate the effectiveness of the proposed approach with respect to robustness and accuracy.
基金Project supported by the National Natural Science Foundation of China (Grant No.61871394)。
文摘Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38%(4.05 GHz–5.95 GHz)and AR bandwidth of 24.9%(4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7%(3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.
文摘Renewable electricity options, such as fuel cells, solar photovoltaic,and batteries, are being integrated, which has made DC micro-grids famous.For DC micro-grid systems, a multi input interleaved non-isolated dc-dcconverter is suggested by the use of coupled inductor techniques. Since itcompensates for mismatches in photovoltaic devices and allows for separateand continuous power flow from these sources. The proposed converter hasthe benefits of high gain, a low ripple in the output voltage, minimal stressvoltage across the power semiconductor devices, a low ripple in inductorcurrent, high power density, and high efficiency. Soft-switching techniquesare used to realize that the reverse recovery issue of the diodes is moderated, the leakage energy is reused, and no new scheme is appropriated. Toreduce conduction losses, minimum voltage rating MOSFETs with a low ONresistance can be utilized. The converter can supply the required power fromthe load in the absence of one or two resources. Furthermore, due to the highgain of boosting voltage, the converter works in an Adaptive Neuro-FuzzyInference System (ANFIS). The operation principle, steady-state analysis ofthe proposed converter, is given and simulated utilizing MATLAB/Simulinksimulation software.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51872043,51732003,and 51902049)the National Key R&D Program of China(Grant No.2019YFA0705202)+2 种基金Natural Science Foundation of Jilin Province,China(Grant No.20200201076JC)the National Basic Research Program of China(Grant No.2012CB933703)“111”Project(Grant No.B13013)。
文摘The defect-related photoconductivity gain and persistent photoconductivity(PPC)observed in Ga_(2)O_(3)Schottky photodetectors lead to a contradiction between high responsivity and fast recovery speed.In this work,a metal-semiconductor-metal(MSM)Schottky photodetector,a unidirectional Schottky photodetector,and a photoconductor were constructed on Ga_(2)O_(3)films.The MSM Schottky devices have high gain(>13)and high responsivity(>2.5 A/W)at 230-250 nm,as well as slow recovery speed caused by PPC.Interestingly,applying a positive pulse voltage to the reverse-biased Ga_(2)O_(3)/Au Schottky junction can effectively suppress the PPC in the photodetector,while maintaining high gain.The mechanisms of gain and PPC do not strictly follow the interface trap trapping holes or the self-trapped holes models,which is attributed to the correlation with ionized oxygen vacancies in the Schottky junction.The positive pulse voltage modulates the width of the Schottky junction to help quickly neutralize electrons and ionized oxygen vacancies.The realization of suppression PPC functions and the establishment of physical models will facilitate the realization of high responsivity and fast response Schottky devices.
基金This work was supported by an Institute for Information and Communications Technology Promotion(IITP),funded by the Korea government(MSIP)(No.2021-0-00490,Devel-opment of precision analysis and imaging technology for biological radio waves).
文摘This paper presents the design of wideband and high gainFrequency Selective Surface(FSS)loaded antenna for ultra-wideband(UWB)wireless applications requiring high-gain.The antenna consists of a monopole and an FSS reflector.Initially,a conventional rectangular monopole antenna is modified using slot and stub to achieve wide operational bandwidth and size reduction.This modified antenna shows 50%miniaturization compared to a primary rectangular monopole,having a wide impedance bandwidth of 3.6-11.8 GHz.Afterward,an FSS is constructed by the combination of circular and square ring structures.The FSS array consisting of 8×8-unit cells are integrated with the antenna as a reflector to enhance the performance of the proposed miniaturized UWB antenna.The loading of FSS results in an improvement of at least 4 dBi gain in the entire operational bandwidth.Moreover,the antenna’s bandwidth is also increased at the lower frequency band due to the presence of the FSS.A prototype of the antenna is fabricated and tested to verify the simulation results.The simulation and measurement results show that the antenna offers a wideband-10 dB impedance bandwidth ranging from 2.55-13GHz with a stable peak gain of 8.6 dBi and retains the radiation pattern stability.
基金Supported by the National Natural Science Foundation of China(No.60777014)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090032110027)
文摘A 16 × 16 micro-strip antenna array with high gain characteristic was proposed for the 5.5 GHz W/MAX application. The T-junctions with a power ratio of 2 ： 1 were used to design the feed network. To correct the stepped discontinuity of impedance change in common multi-section impedance transformer, exponential line matching trans- formers were adopted in the WiMAX frequency band. The reflection coefficient was lower than - 15 dB from 5.08 GHz to 5.87 GHz. The measured gain of the antenna array achieved 29.8 dBi on E-plane at 5.8 GHz.
文摘Renewable energy with sources such as photovoltaic(PV)or fuel cells can be utilized for the generation of elec-trical power.But these sources generate fewer voltage values and therefore require high gain converters to match with DC bus voltage in microgrids.These high gain converters can be implemented with switched capacitors to meet the required DC bus voltage.Switched capacitors operate in a series and parallel combination during switch-ing operation and produce high static gain,limits reverse voltage that appears across the components.A novel converter is proposed that satisfies all the features such as high voltage gain,only one switch,forces less potential stress cross the components,ripple current is less.These features of the proposed converter are verified through MATLAB/SIMULINK.
文摘In this paper, a directional antenna with high gain at low elevation is designed. The antenna uses 12-unit half-wave oscillators for array formation, the antenna voltage standing wave ratio is less than 1.4 in the frequency band of 1400 MHz to 1550 MHz, the pitch surface wave beam range is 0°~40°and the minimum gain of the antenna is ≥ 10dBi in the pitch surface range of 0°~3°and the horizontal plane range ±60°.
文摘A rectangular microstrip patch antenna using conventional Poly Tetra Fluride Ethelene (PTFE) substrate with air cavity is proposed and theoretically investigated. Considerably high gain along with improved front to back radiation isolation is demonstrated using such proposed antenna. The radiation performance of this new antenna has been compared to a conventional microstrip patch for some commonly used aspect ratios (width to length ratio). Compared to conventional microstrip antenna the proposed configuration shows more than 12% increment in peak gain and more than 10% increment in front to back radiation performance in each set of aspect ratio. The elucidation of such improvement in the radiation characteristics of the proposed antenna is also presented.
基金supported by the National Natural Science Foundation of China (61974104)。
文摘In this paper, a wideband high gain millimeter wave radar array antenna based on a wavy power divider was proposed. The radar antenna comprises a wavy power divider and a 10-element array antenna. By adjusting the wavy radius of the power divider, the surface current of the power divider is altered, resulting in better impedance matching with the antenna. This ultimately leads to a significant improvement in bandwidth performance. The 4×10 millimeter wave radar antenna loaded with a wavy power divider exhibits an approximate enhancement of 3 GHz compared to traditional microstrip power divider antennas, and an average gain increase of 2.42 dB within the vehicle millimeter wave radar frequency band relative to the improved gradient power divider structure. The 4×10 millimeter wave radar antenna loaded with wavy power divider possesses the characteristics of high gain and broad bandwidth.
基金supported by the Director’s Fund for the‘Climbing Plan’of the National Space Science Centre of the Chinese Academy of Sciences(No.E2PD10011S)the National Engineering Research Centre for Mobile Private Networks Project(No.BJTU20221102).
文摘This study begins with the fabrication and simulation of high-performance back-illuminated AlGaN-based solar-blind ultraviolet(UV)photodetectors.Based on the photodetectors,a low-noise,high-gain UV detection system circuit is designed and fabricated,enabling the detection,acquisition,and calibration of weak solar-blind UV signals.Experimental results demonstrate that under zero bias conditions,with a UV light power density of 3.45μW/cm^(2) at 260 nm,the sample achieves a peak responsivity(R)of 0.085 A·W^(−1),an external quantum efficiency(EQE)of 40.7%,and a detectivity(D^(*))of 7.46×10^(12) cm·Hz^(1/2)·W^(−1).The system exhibits a bandpass characteristic within the 240–280 nm wavelength range,coupled with a high signal-to-noise ratio(SNR)of 39.74 dB.
基金This work was supported by China Railway Corporation Science and Technology Research and Development Project(P2021J038).
文摘In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.
文摘A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.
基金supported by the National Natural Science Foundation of China(Nos.61376033,61006028)the National High-Tech Program of China(Nos.2012AA012302,2013AA014103)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory
文摘As the front-end preamplifiers in optical receivers, transimpedance amplifiers （TIAs） are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range （DR） to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.
基金Project supported by the National High Technology Research and Development Program of China (No.2007AA01Z2b2)
文摘A low power high gain differential UWB low noise amplifier （LNA） operating at 3-5 GHz is presented. A common gate input stage is used for wideband input matching; capacitor cross coupling （CCC） and current reuse techniques are combined to achieve high gain under low power consumption. The prototypes fabricated in 0.18-μm CMOS achieve a peak power gain of 17.5 dB with a -3 dB bandwidth of 2.8-5 GHz, a measured minimum noise figure （NF） of 3.35 dB and -12.6 dBm input-referred compression point at 5 GHz, while drawing 4,4 mA from a 1.8 V supply. The peak power gain is 14 dB under a 4.5 mW power consumption （3 mA from a 1.5 V supply）. The proposed differential LNA occupies an area of 1,01 mm^2 including test pads.
基金supported by the Important National Science and Technology Specific Projects,China(No.2009ZX01031-002-011)the National Natural Science Foundation of China(No.41274047)the Natural Science Foundation of Jiangsu Province,China(No.BK2012639)
文摘A low power high gain gain-controlled LNA ＋ mixer for GNSS receivers is reported. The high gain LNA is realized with a current source load. Its gain-controlled ability is achieved using a programmable bias circuit. Taking advantage of the high gain LNA, a high noise figure passive mixer is adopted. With the passive mixer, low power consumption and high voltage gain of the LNA ＋ mixer are achieved. To fully investigate the performance of this circuit, comparisons between a conventional LNA ＋ mixer, a previous low power LNA ＋ mixer, and the proposed LNA ＋ mixer are presented. The circuit is implemented in 0.18 #m mixed-signal CMOS technology. A 3.8 dB noise figure, an overall 45 dB converge gain and a 10 dB controlled gain range of the two stages are measured. The chip occupies 0.24 mm2 and consumes 2 mA current under 1.8 V supply.
基金This work was sponsored thought the International Science&Technology Cooperation of China under 2019YFE0100200 and the Fundamental Research Foundation for Universities of Heilongjiang Province(2018-KYYWF-1672).
文摘The development of fuel cell vehicles(FCVs)has a major impact on improving air quality and reducing other fossil-fuel-related problems.DC-DC boost converters with wide input voltage ranges and high gains are essential to fuel cells and DC buses in the powertrains of FCVs,helping to improve the low voltage of fuel cells and“soft”output characteristics.To build DC-DC converters with the desired performance,their topologies have been widely investigated and optimized.Aiming to obtain the optimal design of wide input range and high-gain DC-DC boost converter topologies for FCVs,a review of the research status of DC-DC boost converters based on an impedance network is presented.Additionally,an evaluation system for DC-DC topologies for FCVs is constructed,providing a reference for designing wide input range and high-gain boost converters.The evaluation system uses eight indexes to comprehensively evaluate the performance of DC-DC boost converters for FCVs.On this basis,issues about DC-DC converters for FCVs are discussed,and future research directions are proposed.The main future research directions of DC-DC converter for FCVs include utilizing a DC-DC converter to realize online monitoring of the water content in FCs and designing buck-boost DC-DC converters suitable for high-power commercial FCVs.
