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Admittance of Organic LED Structures with an Emission YAK-203 Layer
摘要： The current-voltage characteristics and admittance of multilayer structures for organic LEDs based on the PEDOT:PSS/NPD/YAK-203/BCP system have been experimentally investigated in a wide range of the measurement conditions. It is shown that at voltages corresponding to the effective radiative recombination of charge carriers, a significant decrease in the differential capacitance of the structures is observed. The frequency dependences of the normalized conductance of LED structures are in good agreement with the results of numerical simulation in the framework of the equivalent circuit method. Changes in the frequency dependences of the admittance with a change in temperature are most pronounced in the temperature range of 200–300 K and less noticeable in the temperature range of 8–200 K. From the frequency dependences of the imaginary part of impedance, the charge carrier mobilities are found at various voltages and temperatures. The mobility values obtained by this method are somewhat lower than those determined by the transient electroluminescence method. The dependence of the mobility on the electric field is well approximated by a linear function. As the temperature decreases from 300 to 220 K, the mobility decreases several times.
关键词： frequency dependence of imaginary part of impedance,LED structure,current-voltage characteristic,transient electroluminescence,organic semiconductor,charge carrier mobility,method of equivalent circuits,admittance
更新于2025-11-14 17:28:48
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Determination of physical mechanism responsible for the capacitance-voltage weak inversion “hump” phenomenon in n-InGaAs based metal-oxide-semiconductor gate stacks
摘要： Weak inversion capacitance-voltage (C-V) “hump” is a widely observed phenomenon at n-InGaAs based metal oxide semiconductor (MOS) structures. The mechanism responsible for this phenomenon is still under discussion. The C-V hump can be explained as an interaction of interface states with either one or both semiconductor energy bands. Each of the proposed mechanisms leads to a different interpretation of C-V hump. Simulating the mechanisms by relevant equivalent circuits, the capacitance and conductance characteristics of the MOS structure were calculated and compared with experimental results. The mechanism responsible for the C-V hump was determined.
关键词： interface states,equivalent circuits,n-InGaAs,metal-oxide-semiconductor,capacitance-voltage hump
更新于2025-11-14 17:28:48
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[IEEE IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - D.C., DC, USA (2018.10.21-2018.10.23)] IECON 2018 - 44th Annual Conference of the IEEE Industrial Electronics Society - Steady-state equivalent circuit of LED bulbs accounting for the current harmonics
摘要： Nowadays, the light-emitting diode (LED) bulb is one of the preferred choice in lighting system design. Electrical models of the LED lamps have to consider their nonlinear behavior involving current distortion on the mains. With this purpose, an equivalent electrical circuit emulating the current drawn by a LED Bulbs is carried out. In this work, different lamps have been tested under variable supply voltage. The comparison between the simulations performed by means of PSpice and the experimental measurements has highlighted that linear interpolation for the amplitude of each harmonic current, as function of the voltage on the main, provides a good estimation of the total current waveform.
关键词： LED Bulbs,power conversion,LED lamps,Current harmonics,equivalent circuits,lighting,total harmonic distortion,power quality
更新于2025-09-19 17:13:59
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Circuit Model of LED Light Bulb suitable for typical voltage THD on LV distribution networks
摘要： In lighting system design, the LED light bulb technology is gaining more and more advantages in comparison to other previous solutions. On the other hand, the designers of lighting systems have to face the specific problems created by this technology in terms of deterioration of the power quality on the mains. The knowledge of lamp electrical models is a key point for the optimal design of the lighting systems but such models are not provided by the manufactures. Moreover, the voltage on the mains may vary along the day due to the load fluctuation as well as due to the variation of the power generated by distributed renewable resources. Consequently, suitable electrical models have to be able at emulating the lamp behavior according to the voltage variability. The paper proposes an equivalent electrical circuit of LED light bulb. The components of the model are identified by means of simple electrical measurements. In particular, the circuit enables to emulate the current waveform in the case of network voltage variability. The validation has highlighted that the simulated currents waveforms have a good matching with the experimental data obtained in presence of distorted voltage on the mains (provided that the voltage THD is compliant with IEEE-Std-519). The validation has been performed also at voltage values different from the ones used for the components identification.
关键词： Current harmonics,power conversion,optimal design,modelling,power quality,lighting,equivalent circuits
更新于2025-09-12 10:27:22
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A new method for determination of PAD capacitances for GaAs HBTs based on scalable small signal equivalent circuit model
摘要： A new direct extraction method to determine the parasitic capacitances for HBTs is presented in this paper. The main advantage is that base parasitic capacitance Cpb can be extracted by using three di?erent size HBTs with the same pad pro?le. This method is based on an improved small-signal model, which takes into account the distribution e?ects of the base and collector feedlines. Good agreement is obtained between the measured and modeled results for the 1 × 3 × 12 μm2, 2 × 2 × 20 μm2 and 1 × 3 × 40 μm2 (number of emitter ?ngers × emitter width × emitter length) GaAs HBTs up to 40 GHz.
关键词： Scalable model,HBT,Parameter extraction,Small signal model,Equivalent circuits
更新于2025-09-09 09:28:46
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Super compact and ultra-wideband bandpass filter with a wide upper stopband based on a SCRLH transmission-line unit-cell and two lumped capacitors
摘要： This paper presents a simplified composite right/left-handed transmission-line (SCRLH-TL) unit-cell, which is primarily consisted of a rectangular ring with two grounded vias. Superposing this unit-cell onto a high–low–high step-impedance resonator (SIR) leads to a novel SCRLH-TL multiple-mode resonator (SCRLH-TL MMR). By combining the SCRLH-TL MMR with a cross-shaped defected ground structure (DGS) and using a broadside coupling approach with two lumped capacitors, a highly compact and ultra-wideband bandpass filter was carefully designed and fully investigated. The filter was fabricated by using a conventional PCB process with the substrate of FR4. The measured 3-dB passband ranges from 2.55 through 11.75 GHz with the fractional bandwidth (FBW) of about 129%. The filter exhibits a high selectivity with steep skirt property, and has a wide upper stopband. Its total dimension, including the rectangular substrate with feed lines, occupies only 13.5 mm × 6.0 mm, which is found with the smallest size in comparison to those recently published in the literature.
关键词： lumped capacitors,Ultra-wideband bandpass filter,defected ground structure,simplified composite right/left-handed transmission-line,equivalent circuits
更新于2025-09-04 15:30:14