In this paper, a practical equivalent circuit of an active flux-controlled memristor characterized by smooth piecewise-quadratic nonlinearity is designed and an experimental chaotic memristive circuit is implemented. ...In this paper, a practical equivalent circuit of an active flux-controlled memristor characterized by smooth piecewise-quadratic nonlinearity is designed and an experimental chaotic memristive circuit is implemented. The chaotic memristive circuit has an equilibrium set and its stability is dependent on the initial state of the memristor. The initial state-dependent and the circuit parameter-dependent dynamics of the chaotic memristive circuit are investigated via phase portraits, bifurcation diagrams and Lyapunov exponents. Both experimental and simulation results validate the proposed equivalent circuit realization of the active flux-controlled memristor.展开更多
In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff'...In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff's current and voltage law. First, parameters are obtained from the I-V (current-voltage) curves for typical monocrystalline silicon solar cells (125 mmx 125 mm). Then, by regarding photo-generated current, shunt resistance, serial resistance of the first solar cell, and resistance load as the variables. The properties of shunt currents (Ishl and Ish2), diode currents (/D1 and/]:)2), and load current (IL) for the whole two serial solar cells are numerically analyzed in these four cases for the first time, and the corresponding physical explanations are made. We find that these parameters have different influences on the internal currents of solar cells. Our results will provide a reference for developing higher efficiency solar cell module and contribute to the better understanding of the reason of efficiency loss of solar cell module.展开更多
A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage-current relationships (VCRs) between two parallel memristive circuits - a parallel memristor and ...A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage-current relationships (VCRs) between two parallel memristive circuits - a parallel memristor and capacitor circuit (the parallel MC circuit), and a parallel memristor and inductor circuit (the parallel ML circuit) - are investigated. The results indicate that the VCR between these two parallel memristive circuits is closely related to the circuit parameters, and the frequency and amplitude of the sinusoidal voltage stimulus. An equivalent circuit model of the memristor is built, upon which the circuit simulations and exper/mental measurements of both the parallel MC circuit and the parallel ML circuit are performed, and the results verify the theoretical analysis results.展开更多
The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components (equivalent circuit parameters) are connected to re...The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components (equivalent circuit parameters) are connected to real and imaginary parts of complex physical coefficients of piezoelectric materials. Based on definitions of dissipation factors, three of them (dielectric, elastic and piezoelectric dissipation factors) are represented by equivalent circuit parameters. Since the equivalent circuit parameters are detectable, the dissipation factors can be easily obtained. In the experiments, the temperature and the stress responses of the three dissipation factors are measured.展开更多
Modeling a memristor is an effective way to explore the memristor properties due to the fact that the memristor devices are still not commercially available for common researchers. In this paper, a physical memristive...Modeling a memristor is an effective way to explore the memristor properties due to the fact that the memristor devices are still not commercially available for common researchers. In this paper, a physical memristive device is assumed to exist whose ionic drift direction is perpendicular to the direction of the applied voltage, upon which, corresponding to the HP charge-controlled memristor model, a novel threshold flux-controlled memristor model with a window function is proposed. The fingerprints of the proposed model are analyzed. Especially, a practical equivalent circuit of the proposed model is realized, from which the corresponding experimental fingerprints are captured. The equivalent circuit of the threshold memristor model is appropriate for various memristors based breadboard experiments.展开更多
Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impeda...Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG&G M283 potentiostat. Equivalent circuit parameters of crystal resonance change significantly during electrodeposition and dissolution of copper in 0.1 mol/L H2SO4 aqueous solution in a cyclic potential sweep experiment, which is explained with an overall picture of mass loading, solution density and viscosity, etc..展开更多
To develop real world memristor application circuits, an equivalent circuit model which imitates memductance (mem- ory conductance) of the HP memristor is presented. The equivalent circuit can be used for breadboard...To develop real world memristor application circuits, an equivalent circuit model which imitates memductance (mem- ory conductance) of the HP memristor is presented. The equivalent circuit can be used for breadboard experiments for various application circuit designs of memristor. Based on memductance of the realistic HP memristor and Chua's circuit a new chaotic oscillator is designed. Some basic dynamical behaviors of the oscillator, including equilibrium set, Lyapunov exponent spectrum, and bifurcations with various circuit parameters are investigated theoretically and numerically. To con- firm the correction of the proposed oscillator an analog circuit is designed using the proposed equivalent circuit model of an HP memristor, and the circuit simulations and the experimental results are given.展开更多
Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In...Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results.展开更多
With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is pa...With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.展开更多
A simple analytical method is presented to analyze the transmission of electromagnetic plane waves through multilayer stacked composite two-dimensional( 2D) structures at microwave frequencies. Unlike the traditional ...A simple analytical method is presented to analyze the transmission of electromagnetic plane waves through multilayer stacked composite two-dimensional( 2D) structures at microwave frequencies. Unlike the traditional structure,high impedance surface with graphene sheet is proposed. The structure includes graphene and thin metal patches and meshes. Simple analytical formulas are introduced for the surface impedance of graphene and for the grid impedance of electrically dense arrays of metal square patches or strips. The result of transmission properties is based on the dynamic tunable model of the high impedance surface,which considers the surface conductivity of graphene layer. The transmission coefficient obtained by using the equivalent circuit method is validated against full-wave numerical simulations. The considered equivalent circuit method can be useful in the design of graphene tunable planar devices.展开更多
An equivalent circuit (EC) method for absorbers design is proposed in this paper. Without using full-wave analysis, the EC method can predict the performance of the absorbers. This method is employed to synthesize b...An equivalent circuit (EC) method for absorbers design is proposed in this paper. Without using full-wave analysis, the EC method can predict the performance of the absorbers. This method is employed to synthesize broadband absorbers by inserting the resistors respectively into the single-and double-square loops structures, then two different prototypes with broadband absorbing frequency bands are manufactured and measured. By comparisons with the results both by using the full-wave analysis and by the measurements, the correctness of the new EC method is verified. Some factors which affect the absorbing bandwidth are also investigated. Due to its fast and accurate characteristics, the EC method which can be theoretically applied to arbitrary FSS is a good candidate for broadband design of the absorbers.展开更多
The crystals of quartz,lithium,and piezoelectric ceramics have a piezoelectric effect as their major characteristic.The surface acoustic wave filter(SAWF) was designed by using this property.However,the experimental c...The crystals of quartz,lithium,and piezoelectric ceramics have a piezoelectric effect as their major characteristic.The surface acoustic wave filter(SAWF) was designed by using this property.However,the experimental cost of the fabrication of SAWF is higher than that of mechanical filter or LC filter.Through the RLC(resistor,inductor and capacitor) network equivalent circuit and the interdigital transducer(IDT) equivalent circuit model,the electromotive force,the mechanical impedance of piezoelectric plate,and the wave number of Mason circuit model were researched.The equivalent circuit can be used to reduce product development costs and shorten the development cycle.Comparing simulation result by Pspice software with the theory of SAWF,the simulated waveform is similar to theory measurement,and the equivalent circuit model is verified.展开更多
In this paper, we present an improved high-frequency equivalent circuit for SiGe heterojunction bipolar transistors(HBTs) with a CBE layout, where we consider the distributed effects along the base region. The actua...In this paper, we present an improved high-frequency equivalent circuit for SiGe heterojunction bipolar transistors(HBTs) with a CBE layout, where we consider the distributed effects along the base region. The actual device structure is divided into three parts: a link base region under a spacer oxide, an intrinsic transistor region under the emitter window,and an extrinsic base region. Each region is considered as a two-port network, and is composed of a distributed resistance and capacitance. We solve the admittance parameters by solving the transmission-line equation. Then, we obtain the smallsignal equivalent circuit depending on the reasonable approximations. Unlike previous compact models, in our proposed model, we introduce an additional internal base node, and the intrinsic base resistance is shifted into this internal base node,which can theoretically explain the anomalous change in the intrinsic bias-dependent collector resistance in the conventional compact model.展开更多
A low temperature sol-gel process was used to fabricate zinc-oxide and yttrium-doped zinc oxide layers. These zinc-oxide and yttrium-doped ZnO films were used as electron transport layers in conjunction with P<sub&...A low temperature sol-gel process was used to fabricate zinc-oxide and yttrium-doped zinc oxide layers. These zinc-oxide and yttrium-doped ZnO films were used as electron transport layers in conjunction with P<sub>3</sub>HT and PC<sub>16</sub>BM type solar cells. It was demonstrated that annealing and doping of electron transport layer influenced the overall organic solar cells performance. Anneals of ~ 150?C provided the highest device performance. Compared to the undoped zinc oxide, the device with yttrium doped zinc oxide layers showed improved efficiency by about 30%. Furthermore an equivalent circuit was proposed to understand the connection between the electrical and optical characteristics of the device. Comparisons between the simulated and experimental current-voltage(I-V) curves displayed only a 1.2% variation between the curves. Clearly, our experimental and simulated studies provide new insight on the equivalent circuit models for inverted organic solar cells and further improvement on photovoltaic efficiency.展开更多
In the process of production, transportation and assembly, cable assemblies can get a lot of electrostatic charge by friction, dragging, pulling and induction. These residual charges can be discharged when Electrostat...In the process of production, transportation and assembly, cable assemblies can get a lot of electrostatic charge by friction, dragging, pulling and induction. These residual charges can be discharged when Electrostatic sensitive device connected with it and can cause the complete failure or potential failure of the electrostatic sensitive product. In this paper, the theoretical model of cable assemblies is established by analyzing the characteristics of cable assemblies, and the equivalent RF circuit is designed. The static discharge characteristics of the cable are analyzed and verified by simulation.展开更多
The extensive research and development in perovskite solar cells (PSCs) have rekindled the hopes of converting solar energy into electricity.An elusive understanding of underlying mechanisms is required for the develo...The extensive research and development in perovskite solar cells (PSCs) have rekindled the hopes of converting solar energy into electricity.An elusive understanding of underlying mechanisms is required for the development of efficient PSCs.Over the years,Impedance Spectroscopy (IS) characterization,along with complementary techniques,has proven to be an effective way to understand and analyze the charge transport and recombination at interface and bulk of PSCs.The IS of PSCs have been analyzed,interpreted,and improvised continuously,revealing intricate details about the work.However,there is a lack of centralized source of these details,which make it tougher to account for the generalized approach to understand the device properties.The present work is focused on compiling the research done on various PSC device architectures via IS to construct a comprehensive foundation of information on impedance plots,equivalent circuits,and associated processes.展开更多
Passive intermodulation(PIM) has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh...Passive intermodulation(PIM) has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal(MM) contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.展开更多
A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with tw...A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.展开更多
This paper compares model differences of transformers measured in 4-port and 2-port configurations. Although 2-port configuration is more appropriate for measurement and application, it brings tremendous difficul- tie...This paper compares model differences of transformers measured in 4-port and 2-port configurations. Although 2-port configuration is more appropriate for measurement and application, it brings tremendous difficul- ties to the model's parameter extraction. In this paper, a physics-based equivalent circuit model and its correspond- ing direct extraction procedure are proposed for on-chip transformers. The extraction is based on the measurement of 2-port configuration instead of the 4-port type, and it can capture the model parameters without any optimiza- tion. In this procedure, a new method has been developed for the parameter extraction of the ladder circuit, which is commonly used to represent the skin effect. Thus, this method can be transferred to the modeling of other passive devices, such as on-chip transmission lines, inductors, baluns, etc. In order to verify the procedure's efficiency and accuracy, an on-chip interleaved transformer in a 90 nm 1P9M CMOS process has been fabricated. We compare the modeled and measured self-inductance, the quality factor, mutual reactive and resistive coupling coefficients. Excellent agreement has been found over a broad frequency range.展开更多
A scalable wideband equivalent circuit model of silicon-based on-chip transmission lines is presented in this paper along with an efficient analytical parameter extraction method based on improved characteristic funct...A scalable wideband equivalent circuit model of silicon-based on-chip transmission lines is presented in this paper along with an efficient analytical parameter extraction method based on improved characteristic function approach,including a relevant equation to reduce the deviation caused by approximation.The model consists of both series and shunt lumped elements and accounts for high-order parasitic effects.The equivalent circuit model is derived and verified to recover the frequency-dependent parameters at a range from direct current to 50 GHz accurately.The scalability of the model is proved by comparing simulated and measured scattering parameters with the method of cascade,attaining excellent results based on samples made from CMOS 0.13 and 0.18 μm process.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province of China (Grant No. BK2009105)
文摘In this paper, a practical equivalent circuit of an active flux-controlled memristor characterized by smooth piecewise-quadratic nonlinearity is designed and an experimental chaotic memristive circuit is implemented. The chaotic memristive circuit has an equilibrium set and its stability is dependent on the initial state of the memristor. The initial state-dependent and the circuit parameter-dependent dynamics of the chaotic memristive circuit are investigated via phase portraits, bifurcation diagrams and Lyapunov exponents. Both experimental and simulation results validate the proposed equivalent circuit realization of the active flux-controlled memristor.
基金Project supported by the National High Technology Research and Development Program of China (Grant No.2012AA050302)the National Natural Science Foundation of China (Grant Nos.61076059 and 51202301)the Science & Technology Research Project of Guangdong Province,China (Grant No.2011A032304001)
文摘In this paper, based on the equivalent single diode circuit model of the solar cell, an equivalent circuit diagram for two serial solar cells is drawn. Its equations of current and voltage are derived from Kirchhoff's current and voltage law. First, parameters are obtained from the I-V (current-voltage) curves for typical monocrystalline silicon solar cells (125 mmx 125 mm). Then, by regarding photo-generated current, shunt resistance, serial resistance of the first solar cell, and resistance load as the variables. The properties of shunt currents (Ishl and Ish2), diode currents (/D1 and/]:)2), and load current (IL) for the whole two serial solar cells are numerically analyzed in these four cases for the first time, and the corresponding physical explanations are made. We find that these parameters have different influences on the internal currents of solar cells. Our results will provide a reference for developing higher efficiency solar cell module and contribute to the better understanding of the reason of efficiency loss of solar cell module.
基金supported by the National Natural Science Foundation of China (Grant No. 51277017)the Natural Science Foundation of Jiangsu Province,China(Grant No. BK2012583)
文摘A flux-controlled memristor characterized by smooth cubic nonlinearity is taken as an example, upon which the voltage-current relationships (VCRs) between two parallel memristive circuits - a parallel memristor and capacitor circuit (the parallel MC circuit), and a parallel memristor and inductor circuit (the parallel ML circuit) - are investigated. The results indicate that the VCR between these two parallel memristive circuits is closely related to the circuit parameters, and the frequency and amplitude of the sinusoidal voltage stimulus. An equivalent circuit model of the memristor is built, upon which the circuit simulations and exper/mental measurements of both the parallel MC circuit and the parallel ML circuit are performed, and the results verify the theoretical analysis results.
基金Project supported by the National Natural Science Foundation of China (Grant No 50278098).
文摘The equivalent circuit with complex physical constants for a piezoelectric ceramic in thickness mode is established. In the equivalent circuit, electric components (equivalent circuit parameters) are connected to real and imaginary parts of complex physical coefficients of piezoelectric materials. Based on definitions of dissipation factors, three of them (dielectric, elastic and piezoelectric dissipation factors) are represented by equivalent circuit parameters. Since the equivalent circuit parameters are detectable, the dissipation factors can be easily obtained. In the experiments, the temperature and the stress responses of the three dissipation factors are measured.
基金supported by the National Natural Science Foundation of China(Grant No.51277017)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2012583)
文摘Modeling a memristor is an effective way to explore the memristor properties due to the fact that the memristor devices are still not commercially available for common researchers. In this paper, a physical memristive device is assumed to exist whose ionic drift direction is perpendicular to the direction of the applied voltage, upon which, corresponding to the HP charge-controlled memristor model, a novel threshold flux-controlled memristor model with a window function is proposed. The fingerprints of the proposed model are analyzed. Especially, a practical equivalent circuit of the proposed model is realized, from which the corresponding experimental fingerprints are captured. The equivalent circuit of the threshold memristor model is appropriate for various memristors based breadboard experiments.
文摘Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG&G M283 potentiostat. Equivalent circuit parameters of crystal resonance change significantly during electrodeposition and dissolution of copper in 0.1 mol/L H2SO4 aqueous solution in a cyclic potential sweep experiment, which is explained with an overall picture of mass loading, solution density and viscosity, etc..
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61271064 and 60971046)the Natural Science Foundation of Zhejiang Province,China(Grant No.LZ12F01001)the Program for Zhejiang Leading Team of Science and Technology Innovation,China(Grant No.2010R50010-07)
文摘To develop real world memristor application circuits, an equivalent circuit model which imitates memductance (mem- ory conductance) of the HP memristor is presented. The equivalent circuit can be used for breadboard experiments for various application circuit designs of memristor. Based on memductance of the realistic HP memristor and Chua's circuit a new chaotic oscillator is designed. Some basic dynamical behaviors of the oscillator, including equilibrium set, Lyapunov exponent spectrum, and bifurcations with various circuit parameters are investigated theoretically and numerically. To con- firm the correction of the proposed oscillator an analog circuit is designed using the proposed equivalent circuit model of an HP memristor, and the circuit simulations and the experimental results are given.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339803)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+5 种基金the National Natural Science Foundation of China(Grant Nos.61131006,61321492,and 61404149)the Major National Development Project of Scientific Instrument and Equipment,China(Grant No.2011YQ150021)the National Science and Technology Major Project,China(Grant No.2011ZX02707)the Major Project,China(Grant No.YYYJ-1123-1)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology,China(Grant Nos.14530711300)
文摘Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61434006 and 61704189)the Fund from the Youth Innovation Promotion Association of the Chinese Academy of Sciences。
文摘With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.
基金Supported in part by the Funding of Jiangsu Innovation Program for Graduate Education(KYLX-0275,KYLX-0276)the Fundamental Research Funds for the Central Universitiesthe Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A simple analytical method is presented to analyze the transmission of electromagnetic plane waves through multilayer stacked composite two-dimensional( 2D) structures at microwave frequencies. Unlike the traditional structure,high impedance surface with graphene sheet is proposed. The structure includes graphene and thin metal patches and meshes. Simple analytical formulas are introduced for the surface impedance of graphene and for the grid impedance of electrically dense arrays of metal square patches or strips. The result of transmission properties is based on the dynamic tunable model of the high impedance surface,which considers the surface conductivity of graphene layer. The transmission coefficient obtained by using the equivalent circuit method is validated against full-wave numerical simulations. The considered equivalent circuit method can be useful in the design of graphene tunable planar devices.
基金Project supported by the Science Foundation for New Century Excellent Talents in University of China (Grant No. NCET-10-0894)
文摘An equivalent circuit (EC) method for absorbers design is proposed in this paper. Without using full-wave analysis, the EC method can predict the performance of the absorbers. This method is employed to synthesize broadband absorbers by inserting the resistors respectively into the single-and double-square loops structures, then two different prototypes with broadband absorbing frequency bands are manufactured and measured. By comparisons with the results both by using the full-wave analysis and by the measurements, the correctness of the new EC method is verified. Some factors which affect the absorbing bandwidth are also investigated. Due to its fast and accurate characteristics, the EC method which can be theoretically applied to arbitrary FSS is a good candidate for broadband design of the absorbers.
基金National Natural Science Foundation of China (No.60976058)
文摘The crystals of quartz,lithium,and piezoelectric ceramics have a piezoelectric effect as their major characteristic.The surface acoustic wave filter(SAWF) was designed by using this property.However,the experimental cost of the fabrication of SAWF is higher than that of mechanical filter or LC filter.Through the RLC(resistor,inductor and capacitor) network equivalent circuit and the interdigital transducer(IDT) equivalent circuit model,the electromotive force,the mechanical impedance of piezoelectric plate,and the wave number of Mason circuit model were researched.The equivalent circuit can be used to reduce product development costs and shorten the development cycle.Comparing simulation result by Pspice software with the theory of SAWF,the simulated waveform is similar to theory measurement,and the equivalent circuit model is verified.
基金Project supported by the National Natural Science Funds of China(Grant Nos.61574056 and 61504156)the Natural Science Foundation of Shanghai,China(Grant No.14ZR1412000)+1 种基金Shanghai Sailing Program,China(Grant No.17YF1404700)the Science and Technology Commission of Shanghai Municipality,China(Grant No.14DZ2260800)
文摘In this paper, we present an improved high-frequency equivalent circuit for SiGe heterojunction bipolar transistors(HBTs) with a CBE layout, where we consider the distributed effects along the base region. The actual device structure is divided into three parts: a link base region under a spacer oxide, an intrinsic transistor region under the emitter window,and an extrinsic base region. Each region is considered as a two-port network, and is composed of a distributed resistance and capacitance. We solve the admittance parameters by solving the transmission-line equation. Then, we obtain the smallsignal equivalent circuit depending on the reasonable approximations. Unlike previous compact models, in our proposed model, we introduce an additional internal base node, and the intrinsic base resistance is shifted into this internal base node,which can theoretically explain the anomalous change in the intrinsic bias-dependent collector resistance in the conventional compact model.
文摘A low temperature sol-gel process was used to fabricate zinc-oxide and yttrium-doped zinc oxide layers. These zinc-oxide and yttrium-doped ZnO films were used as electron transport layers in conjunction with P<sub>3</sub>HT and PC<sub>16</sub>BM type solar cells. It was demonstrated that annealing and doping of electron transport layer influenced the overall organic solar cells performance. Anneals of ~ 150?C provided the highest device performance. Compared to the undoped zinc oxide, the device with yttrium doped zinc oxide layers showed improved efficiency by about 30%. Furthermore an equivalent circuit was proposed to understand the connection between the electrical and optical characteristics of the device. Comparisons between the simulated and experimental current-voltage(I-V) curves displayed only a 1.2% variation between the curves. Clearly, our experimental and simulated studies provide new insight on the equivalent circuit models for inverted organic solar cells and further improvement on photovoltaic efficiency.
文摘In the process of production, transportation and assembly, cable assemblies can get a lot of electrostatic charge by friction, dragging, pulling and induction. These residual charges can be discharged when Electrostatic sensitive device connected with it and can cause the complete failure or potential failure of the electrostatic sensitive product. In this paper, the theoretical model of cable assemblies is established by analyzing the characteristics of cable assemblies, and the equivalent RF circuit is designed. The static discharge characteristics of the cable are analyzed and verified by simulation.
基金the ORSP of Pandit Deendayal Energy University and DST SERB(IPA/2021/96)for the financial support.
文摘The extensive research and development in perovskite solar cells (PSCs) have rekindled the hopes of converting solar energy into electricity.An elusive understanding of underlying mechanisms is required for the development of efficient PSCs.Over the years,Impedance Spectroscopy (IS) characterization,along with complementary techniques,has proven to be an effective way to understand and analyze the charge transport and recombination at interface and bulk of PSCs.The IS of PSCs have been analyzed,interpreted,and improvised continuously,revealing intricate details about the work.However,there is a lack of centralized source of these details,which make it tougher to account for the generalized approach to understand the device properties.The present work is focused on compiling the research done on various PSC device architectures via IS to construct a comprehensive foundation of information on impedance plots,equivalent circuits,and associated processes.
文摘Passive intermodulation(PIM) has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal(MM) contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.
基金This work was supported by the Key Projects of the National Natural Science Foundation of China (Grant No. 51537007) and the National Natural Science Foundation of China (Grant No. 51277125).
文摘A brushless electrically excited synchronous generator (BEESG) with a hybrid rotor is a novel electrically excited synchronous generator. The BEESG proposed in this paper is composed of a conventional stator with two different sets of windings with different pole numbers, and a hybrid rotor with powerful coupling capacity. The pole number of the rotor is different from those of the stator windings. Thus, an analysis method different from that applied to conventional generators should be applied to the BEESG. In view of this problem, the equivalent circuit and electromagnetic torque expression of the BEESG are derived on the basis of electromagnetic relation of the proposed generator. The generator is simulated and tested experimentally using the established equivalent circuit model. The experimental and simulation data are then analyzed and compared. Results show the validity of the equivalent circuit model.
基金Project supported by the Yangzi-Delta Cooperative Projects of Zhejiang Province,China
文摘This paper compares model differences of transformers measured in 4-port and 2-port configurations. Although 2-port configuration is more appropriate for measurement and application, it brings tremendous difficul- ties to the model's parameter extraction. In this paper, a physics-based equivalent circuit model and its correspond- ing direct extraction procedure are proposed for on-chip transformers. The extraction is based on the measurement of 2-port configuration instead of the 4-port type, and it can capture the model parameters without any optimiza- tion. In this procedure, a new method has been developed for the parameter extraction of the ladder circuit, which is commonly used to represent the skin effect. Thus, this method can be transferred to the modeling of other passive devices, such as on-chip transmission lines, inductors, baluns, etc. In order to verify the procedure's efficiency and accuracy, an on-chip interleaved transformer in a 90 nm 1P9M CMOS process has been fabricated. We compare the modeled and measured self-inductance, the quality factor, mutual reactive and resistive coupling coefficients. Excellent agreement has been found over a broad frequency range.
基金supported by National Natural Science Foundation of China(No.61674036)
文摘A scalable wideband equivalent circuit model of silicon-based on-chip transmission lines is presented in this paper along with an efficient analytical parameter extraction method based on improved characteristic function approach,including a relevant equation to reduce the deviation caused by approximation.The model consists of both series and shunt lumped elements and accounts for high-order parasitic effects.The equivalent circuit model is derived and verified to recover the frequency-dependent parameters at a range from direct current to 50 GHz accurately.The scalability of the model is proved by comparing simulated and measured scattering parameters with the method of cascade,attaining excellent results based on samples made from CMOS 0.13 and 0.18 μm process.