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Guo B.,China Electronics Technology Group Corporation | Zhang Q.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Frequenz | Year: 2013

To improve thermal stability and relieve current convergence in rf power bjts, an embedded active CMOS ballast circuit is proposed. By detecting the inhomogeneous temperature through distributed temperature sensors, the adjacent ballast circuit is triggered to shunt the base convergence current of the power BJT cell, performing the ballast protection for the device. Simulations and measurements validate the effectiveness of the proposed ballast circuit. Compared to conventional ballast resistor methods, the improved device integrated with ballast circuits exhibits superior electrical performance. The single ballast circuit only consumes 6.5 mW with additional occupied area of 2530 um2. Source

Lin Z.,Chongqing University of Science and Technology | Cai W.,Chongqing University of Science and Technology | Jiang W.,Chongqing University of Science and Technology | Fu C.,Chongqing University of Science and Technology | And 3 more authors.
Ceramics International | Year: 2013

Bismuth ferrite thin films were prepared via sol-gel spin-coating method and the effects of annealing temperature on microstructure, optical, ferroelectric and photovoltaic properties have been investigated. The results show that the bismuth ferrite thin films annealed at 550 C is single phase and the grain size increases with the rise of annealing temperature. The band gap of bismuth ferrite thin films annealed at 550-650 C is between 2.306 eV and 2.453 eV. With the rise of the annealing temperature, the remnant polarization gradually decreases and the coercive electric field increases. The short circuit photocurrent density decreases with the rise of annealing temperature, and the open circuit photovoltage and the power conversion efficiency of bismuth ferrite thin films annealed at 550 C are higher than the thin films annealed at higher temperature. © 2013 Elsevier Ltd and Techna Group S.r.l. Source

Li C.,Liaocheng University | Wang M.,Liaocheng University | Wang M.,The Central Laboratory of Liaocheng Hospital | Cui C.,Liaocheng University | And 3 more authors.
International Journal of Electrochemical Science | Year: 2012

1,4-Bis(2-thienyl)-naphthalene (BTN) monomer is successfully synthesized via coupling reaction. Direct anodic oxidation of BTN monomer leads to the formation of a novel poly(1,4-bis(2-thienyl)-naphthalene) (PBTN) on a platinum wire in acetonitrile (ACN). The resultant polymer is investigated by cyclic voltammetry (CV) and characterized by FT-IR, 1H NMR, and UV-vis spectra. The oligomer of resultant polymer is soluble in N, N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). Fluorescence spectra studies reveal that PBNT is a green-light emitter (emission at 514 nm) and the photoluminescence (PL) quantum yield (Ø) is 0.235 in DMF solution. According to the spectroelectrochemical analyses, PBTN film presents multielectrochromic property and shows four different colors under various potentials. Electrochromic switching of PBTN film is performed and the polymer film shows a maximum optical contrast (ΔT %) of 24% at 700 nm in visible region with a response time of 1.78 s. The coloration efficiency (CE) of PBTN is calculated to be 124.8 cm 2 C -1. The multichromic polymer is thermally stable up to 496 °C. SEM images illustrate that the polymer film presents a porous structure. Source

Tao Z.,University of Electronic Science and Technology of China | Tao Z.,State Key Laboratory of Electronic Thin Films and Integrated Devices | He W.,University of Electronic Science and Technology of China | Wang S.,University of Electronic Science and Technology of China | And 2 more authors.
Corrosion Science | Year: 2012

The nitrophenyltriazole derivative, namely 2-[1,2,4]-triazole-methyl-4-acetyl-5-nitrophenyl-[1,3,4]-oxadiazole (TMANO) was synthesized and its inhibiting action on the corrosion of mild steel in 0.5M H 2SO 4 solution was investigated by weight loss test, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscopy (SEM). The selective desorption of TMANO from mild steel surface was also studied by the differential polarization curves. Both thermodynamic and kinetic parameters were calculated and discussed. The results showed that the adsorption of TMANO on steel surface obeys the Langmuir adsorption isotherm. The calculated values of ΔHads0 and ΔSads0 indicated that the adsorption process of TMANO on steel surface was exothermic and accompanied by a decrease in entropy. © 2012 Elsevier Ltd. Source

Che Y.-X.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Hou X.-Y.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2011

For planar periodic structure with finite thickness, the paper presents an algorithm, integral equations solved by method of moments (IE-MoM), making a quickly and effectively calculation of the electromagnetic characteristics. A detailed electromagnetic characteristics analysis is done about frequency selective surfaces (FSS) with four-legged loaded elements. The paper presents the reflection and transmission coefficients, radiation pattern, and surface electric field distribution for the FSS with different thickness. Through the analysis, it is found that the thickness of the metal screen makes a difference for the electromagnetic characteristics of the FSS in higher frequency resonant. In addition, a good agreement can be observed between the results of simulations obtained from our approach and with the commercial software HFSS. The computer time is also improved greatly. © 2011 by Editorial Department of Chinese Journal of Radio Science. Source

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