查看更多>>摘要：With the rapid development of space-air-ground integrated communications,diverse requirements have been imposed on antenna radiation patterns.In addition,increasingly compact platforms brings significant challenges to the deployment of antenna arrays normally used for beamforming.This article comprehensively surveys characteristic mode analysis(CMA)-based pattern diversity realizations in past years.Specifically,exciting multiple characteristic modes independently achieves pattern reconfigurability and element-reduced multiple-input and multiple-output sys-tems.We furthermore overview a series of works on modes superposition.Various methods have been explored for modal weights decision,and therefore specific patterns are synthesized.The weighted modal combination also fulfills single-element beamforming.A recent study on an antenna design for electrically small unmanned aerial vehicles(UAVs)is summarized,and the desired reconfigurable radiation patterns of the conformal radiator are realized based on CMA.Moreover,a formation-based beamforming technique,which takes advantages of the electromagnetic coup-ling among conformal radiators and the agility of UAVs,is introduced.
查看更多>>摘要：A silicon carbide(SiC)double trench metal-oxide-semiconductor field effect transistor(DTMOS)with split gate(SG)and integrated Schottky barrier diode(SBD)is proposed for the first time.The proposed device features two enhanced deep trenches in the surface,in which a source-connected SG with a thicker dielectric layer is located at the bottom of the deep gate trench and an integrated SBD is located at the sidewall of the deep source trench(DST).Combined with shielding effect provided by the P+shield layer under the DST and integrated SBD,the pro-posed structure not only reduces the reverse transfer capacitance(Crss)and gate-drain charge(Qgd)but also restrains the saturation drain current(Id,sat)and improves the diode performance of the device.Numerical analysis results show that compared with the Con-DTMOS and Con-DTMOS with external SBD diode,the turn-on loss(Eon)and turn-off loss(Eoff)for the proposed device are reduced by 56.4％/70.4％and 56.6％/69.9％,respectively.Moreover,the Id,sat at the Vgs of 18 V for the proposed device is reduced by 74.4％and the short-circuit withstand time(tsc)is im-proved by about 7.5 times.As a result,an ultra-low power loss and improved short-circuit capability is obtained for the proposed device.
查看更多>>摘要：Memristors are a promising solution for building an advanced computing system due to their excellent characteristics,including small energy consumption,high integration density,fast write/read speed,great endurance and so on.In this work,we firstly design three basis logic XNOR1,XNOR2 and XOR gates by virtue of memristor ratioed logic(MRL),and further construct 1-bit numerical comparators,2-bit numerical comparators and full adder 1 based on the above XNOR1,XNOR2 and XOR gates.Furthermore,we propose and design a universal logic circuit that can realize four different kinds of logic functions(AND,OR,XOR,XNOR)at the same time.Subsequently,a full adder 2 is built using XOR function of this universal logic circuit.Compared with the traditional CMOS circuits,the universal logic circuit designed in this work exhibits several merits such as fewer components,less power,and lower delay.This work demonstrates that memristors can be used as a potential solution for building a novel com-puting architecture.
查看更多>>摘要：Crystal oscillators(XOs)provide a high-precision reference frequency but have a long startup time,which severely increases the average power consumption in duty-cycled systems.This paper proposes a fully-digital low-cost two-step injection technique,by using a successive approximation register(SAR)based auto frequency control(AFC)loop,to speed up the startup behavior of XOs.A theoretical analysis is carried out to determine the optimum injection time and design low-power XOs.Fabricated in a 65 nm CMOS process,the proposed 12 MHz fast startup XO occupies an active area of 0.02 mm2 and achieves a startup time less than 35 μs.The XO power consumption in the steady state is 40 μW from a 1.0-V supply,with a startup energy of 17.2 nJ.
查看更多>>摘要：Aiming at the impact of load current change on single-event transient,the essential difference be-tween single-event transient and load transient of DC-DC converter is deeply studied.A hardened circuit based on load transient detection is proposed.The circuit detects the load transient information in time and outputs a control signal to control the single event hardened circuit,thereby realizing the improvement of the transient characteristics of the system under dynamic conditions.Based on the 180 nm bipolar-CMOS-DMOS(BCD)process,the design and physical verification of a boost converter are completed.The experimental results show that the input voltage range is 2.9-4.5 V,the output voltage range is 5.8-7.9 V,and the load current is 0-55 mA.During load transients,the load detection circuit turns off the hardened circuit in time,avoiding system oscillation and widening the dynamic range of the hardening circuit.Under the single-event transient,the output voltage fluctuation of the system does not ex-ceed the maximum ripple voltage,and the single-event transient suppression ability reaches more than 86％,the sys-tem can work well with linear energy transfer of about 100 MeV·cm2/mg.
查看更多>>摘要：Area has become one of the main bottlenecks restricting the development of integrated circuits.The area optimization approaches of existing XNOR/OR-based mixed polarity Reed-Muller(MPRM)circuits have poor optimization effect and efficiency.Given that the area optimization of MPRM logic circuits is a combinatorial opti-mization problem,we propose a whole annealing adaptive bacterial foraging algorithm(WAA-BFA),which includes individual evolution based on Markov chain and Metropolis acceptance criteria,and individual mutation based on adaptive probability.To address the issue of low conversion efficiency in existing polarity conversion approaches,we introduce a fast polarity conversion algorithm(FPCA).Moreover,we present an MPRM circuits area optimization approach that uses the FPCA and WAA-BFA to search for the best polarity corresponding to the minimum circuits area.Experimental results demonstrate that the proposed MPRM circuits area optimization approach is effective and can be used as a promising EDA tool.
查看更多>>摘要：Three-atoms-type V2C MXene,an emerging class of transition metal carbides,has attracted tremendous attention in the fabrication of advanced memristive devices due to its excellent electrochemical properties.However,the inserted effects and corresponding physical mechanisms of inserting V2C on traditional TiO2-based memristors have not been clearly explored.In this work,exhaustive electrical characterizations of the V2C/TiO2-based devices exhibit enhanced performance(e.g.,improved switching stability and lower operating voltages)compared to the TiO2-based counterparts.In addition,the advantaged influences of the inserted V2C have also been studied by means of first-principles calculations,confirming that V2C MXene enables controllable internal ionic process and facilitated formation mechanism of the Ag conductive filaments.This work demonstrates a way to combine experimental and theoretical investigations to reveal the positive effects of introducing V2C MXene on memristor,which is beneficial for fabricating performance-enhanced memristors.
查看更多>>摘要：In this paper,a static deflection model of MEMS cantilever beam is proposed,which can better study the force deformation of micro-electro-mechanical system(MEMS)cantilever beam and the output characteristics of capacitive microwave power sensor.The deflection curve is used to describe the deformation of the cantilever beam and then the overload power and sensitivity of this power sensor are derived.It is found that the overload power de-creases with the beam length,and increases with the initial height of beam.The sensitivity increases with the beam length,and has a linear growth relationship with the measuring electrode width.A MEMS dual-channel microwave power sensor is designed,fabricated and measured.At a microwave signal frequency of 10 GHz,the sensitivity of the sensor is measured to be 0.11 V/W for the thermoelectric detection channel and 65.17 fF/W for the capacitive detec-tion channel.The sensitivity calculated by the lumped model is 92.93 fF/W,that by the pivot model is 50.88 fF/W,and that by the deflection model proposed in this work is 75.21 fF/W.Therefore,the theoretical result of the static deflection model is more consistent with the measured result and has better accuracy than the traditional lumped model and pivot model.
查看更多>>摘要：The study focuses on the development of gallium nitride(GaN)Schottky barrier diode(SBD)fre-quency doublers for terahertz technology.The low conversion efficiency of these doublers limits their practical appli-cations.To address this challenge,the paper proposes a multi-objective local no-reflection design method based on a three-dimensional electromagnetic structure.The method aims to improve the coupling efficiency of input power and reduce the reflection of power output.Experimental results indicate that the proposed method significantly improves the performance of GaN SBD frequency doublers,achieving an efficiency of 16.9％and a peak output power of 160 mW at 175 GHz.These results suggest that the method can contribute to the further development of GaN SBD fre-quency doublers for terahertz technology.
查看更多>>摘要：In this paper,a double-balanced doubler chain with＞43-dBc fundamental rejection over an ultra-wide bandwidth in 0.13-µm SiGe BiCMOS technology is proposed.To achieve high fundamental rejection,high output power,and high conversion gain over an ultra-wideband,a double-balanced doubler chain with pre-and post-drivers employs a bandwidth broadening technique and a ground shielding strategy.Analysis and comparison of the single-balanced and double-balanced doublers were conducted,with a focus on their fundamental rejection and circuit imbalance.Three doublers,including a passive single-balanced doubler,an active single-balanced doubler,and a pas-sive double-balanced doubler were designed to verify the performance and characteristics of the single-and double-balanced doublers.Measurements show that the proposed double-balanced doubler chain has approximately 15 dB better fundamental rejection,and more than twice the relative bandwidth compared to the single-balanced doubler chain fabricated with the same process.Over an 86.9％3-dB bandwidth from 13.4 GHz to 34 GHz,the double-balanced doubler chain delivers 14.7-dBm peak output power and has＞43-/33-dBc fundamental/third-harmonic rejection.To the authors'best knowledge,the proposed double-balanced doubler chain shows the highest fundamental rejection over an ultra-wideband among silicon-based doublers at millimeter-wave frequency bands.
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