Browsing by Author "Lu, Chun-An"

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A 918MHz Wide-Range CMOS Rectifier with Diode-Feeding and Switch-Capacitor-Based Load Modulation Technique
(2019-01-01)
Kuo, Chen-Yi
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Lu, Chun-An
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Liao, Yu-Te
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交大名義發表
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National Chiao Tung University
This paper presents a wide-input-range rectifier design with a diode-feeding (DF) architecture and load modulation. Dynamically-biased diodes are connected to the gates of the rectifying transistors to create bias voltage differences for PMOS and NMOS devices and the isolation of the reverse currents at different input power levels. Also, the switch-capacitor-based load modulation scheme is proposed to achieve optimal efficiency over wide-range load current deviations automatically. The proposed four-stage rectifier design was fabricated using 65nm CMOS technology and occupies a silicon area of 0.92 x 0.27mm(2). The measured sensitivity of the rectifier is -15dBm at 1M Omega load, and the peak power conversion efficiency is 28% at a load of 22k Omega With the load modulation scheme, the conversion efficiency is enhanced by >10% in a load current from 7 mu A to 35 mu A, when compared to a design without the load modulation scheme.
Characterization of the low-curing-temperature silver paste with silver 2-ethylhexanoate addition
(2007-01-01)
Lu, Chun-An
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Lin, Pang
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Lin, Hong-Ching
;
Wang, Sea-Fue
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材料科學與工程學系
In this study, the effects of the solvent and atmosphere on the thermal decomposition behaviors of silver 2-ethylhexanoate and alpha-terpenol are investigated. Low-curing-temperature silver pastes made from Ag flakes, alpha-terpineol and various amounts of silver 2-ethylhexanoate, were prepared and characterized. The microstructures and resistivities of cured films screen-printed from the pastes were examined. The results of thermal analysis in oxidizing and reducing atmospheres revealed that thermal decomposition is the dominating reaction during the heating process of silver 2-ethylhexanoate, even though the differential scanning calorimetry (DSC) result revealed an exothermic reaction for silver 2-ethylhexanoate heated in air due to oxidation. Thermal decomposition left almost pure Ag particles, which is beneficial for bridging between silver flake particles in the films. On the basis of the theological behavior, microstructural evolution and electrical evaluation, it can be concluded that a low-curing-temperature silver paste with 5 wt % silver 2-ethylhexanoate addition is the best formulation, which possesses shear-thinning and thixotropic properties and a resistivity of 7.8 x 10(-6) Omega cm after being cured at 250 degrees C, which is relatively close to the bulk resistivity of Ag.
Effects of metallo-organic decomposition agents on thermal decomposition and electrical conductivity of low-temperature-curing silver paste
(2006-09-01)
Lu, Chun-An
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Lin, Pang
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Lin, Hong-Ching
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Wang, Sea-Fue
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材料科學與工程學系
Six low-temperature-curing silver pastes were prepared from silver flake, alpha-terpineol and, various metallo-organic decomposition (MOD) compounds. The thermal decomposition behaviors of the pastes were determined. The microstructures and resistivities of screen-printed films on alumina substrate after thermal treatment were characterized and discussed. Results indicated that 2-ethylhexanoate possesses the lowest decomposition temperature (190.3 degrees C) among the MOD agents studied, and it forms silver particles to promote the linking of silver flake powders and thus reduces the resistivity to < 13 mu Omega.cm at a temperature as low as 200 degrees C.
Effects of silver oxalate additions on the physical characteristics of low-temperature-curing MOD silver paste for thick-film applications
(2009-11-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
;
Wang, Sea-Fue
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材料科學與工程學系
In this paper, the effect of silver oxalate addition on physical characteristics of metallo-organic-decomposition (MOD) silver screen-printable paste for thick film technology was investigated. The addition of silver oxalate in the paste not only produces fresh fine silver particles after curing, but also reduces the decomposition temperature of the lubricant coated on the silver flakes. This is an effective route to provide fine silver particles to the paste without significantly changing the theological behavior. At the curing temperature of 225 degrees C, the resistivity decreases from 180.1 to 31.9 mu Omega-cm, as the silver oxalate content increases from 0 to 10 wt%. This is due to the fact that active silver catalysts produced increase the packing density of silver flakes, and also the removal of lubricant from the surface of silver flakes enhances the electrical conductivity, thereby decreasing the resistance of film. (C) 2009 Elsevier B.V. All rights reserved.
Effects of silver oxide addition on the electrical resistivity and microstructure of low-temperature-curing metallo-organic decomposition silver pastes
(2007-07-01)
Lu, Chun-An
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Lin, Pan
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Lin, Hong-Ching
;
Wang, Sea-Fue
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材料科學與工程學系
The thermal decomposition of silver paste with the addition of a metallo-organic decomposition (MOD) compound generally requires a curing time of greater than 10 min and a curing temperature greater than 250 degrees C, which does not meet the requirement for high-speed production in flexible substrates. In this study, attempts to modify the curing conditions of MOD silver pastes through the substitutions of silver flakes with silver(I) oxide (Ag2O) and silver(II) oxide (AgO) were performed. Differential thermal analysis (DTA), derivative thermogravimetric analysis (DTG), and X-ray diffraction (XRD) results indicated that the presence of residual silver oxide, which effectively catalyzes the evaporation of a-terpineol and the decomposition of silver 2-ethyl hexanoate, decreases the curing temperature and shortens the soaking time. The reduced silver and the remaining AgO enhance the connectivity and packing density of the silver flakes, and thus increase the electric conductivity of the films. For films prepared from pastes with 20 wt % Ag2O or AgO, resistivities of 14 x 10(-6) and 19 x 10(-6) mu Omega center dot cm. respectively, were successfully achieved after being cured at 200 degrees C for 5 min.
Growth of diamond nanoplatelets by CVD
(2008-07-01)
Chen, Hou-Guang
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Chang, Li
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Cho, Shih-Yin
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Yan, Jhih-Kun
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Lu, Chun-An
Hexagonal, single-crystalline, diamond nanoplatelets synthesized by microwave plasma (MP)CVD on Au-Ge alloy and nanocrystalline diamond (nc-diamond) film substrates, respectively, are reported. On the nc-diamond matrix, hexagonal diamond nanoplatelets can grow to a thickness of as little as approximately 10 nm. The effects of various processing parameters, such as methane concentration, microwave power, and gas pressure, on the growth of diamond nanoplatelets are explored. High-resolution transmission electron microscopy (HRTEM) reveals that the diamond nanoplatelets contain multi-parallel twins, and the side faces of the platelets exhibit {100}/{111} ridge-and-trough structure. Anisotropic growth of diamond nanoplatelet is believed to result from the side face structure of the twinned platelets and intensive plasma reaction.
High-frequency electrical properties of silver thick films measured by dielectric resonator method
(2008-09-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
;
Wang, Sea-Fue
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材料科學與工程學系
The electrical properties of silver films, prepared using a low-curing-temperature metallo-organic-decomposition (MOD) paste and a high-temperature silver paste screen-printed on polished and nonpolished alumina substrates, at microwave frequency were characterized in this Study. Surface resistance and effective conductivity of the silver films at microwave frequency (approximately 4 GHz) were evaluated using the TE(011) mode of the resonator cavities method. Devices of T-type resonator circuits were fabricated to determine the simulated and measured Q-values and to evaluate the effects of silver films and the surrounding substrate. The surface roughness of the fired films printed on nonpolished Al(2)O(3) substrate is slightly less than those on polished Substrate. because the surface energy of the nonpolished alumina (29.81 mN/m) is slightly less than that of the polished alumina (36.69 mN/m). The calculated effective conductivities at 4.3 GHz are slightly less than the DC conductivities of the films. Moreover, the films prepared using the high temperature silver paste have higher electrical conductivity ranging from 4.08 x 10(7) to 4.13 x 10(7) S/m, Since the high-temperature firing process leads to an improved connectivity of the silver particles. The results indicate that the films screen-printed on the polished substrate have a higher Q and a lower Delta Q value than those of films that are screen-printed on the nonpolished substrate. For the silver films prepared using the high-temperature silver paste, both the Q and Delta Q values were the highest among the films studied, which is consistent with the observation of the dense microstructure of the silver film and the interfacial reaction between the Mass in the film and tie Substrate as a result of high firing temperature.
Microstructure and Electrical Resistivity of Low-Temperature-Cured Silver Films Prepared Using Silver Oxide and Silver Stearate Pastes
(2009-01-01)
Lin, Hong-Ching
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Lin, Pang
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Lu, Chun-An
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Wang, Sea-Fue
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材料科學與工程學系
In this study, paste formulations containing silver oxide coated with a metallo-organic decomposition (MOD) agent of silver stearate were prepared without using any silver powders or silver flakes. Results indicate that all pastes appear to have a pseudoplastic flow property that is acceptable for roll-to-roll printing and screen printing. The pastes were screen-printed on an alumina substrate and then thermally treated in a range of temperatures. The lowest electrical resistivity of 13.2 x 10(-6) Omega.cm was obtained for the film prepared from paste with a Ag(2)O/silver stearate ratio of 100 : 5 at a solid loading of 80 wt % in the solvent a-terpineol, after being cured at 160 degrees C for 5 min, which meets the requirements of low-temperature and high-speed manufacturing for practical applications. The low resistivity of the film is facilitated by the combination of Ag(2)O and silver stearate added to the paste. Ag(2)O produces a high density of silver matrix after being reduced at low temperatures, and the presence of silver stearate contributes to the rheological behavior of the paste after dissolution in the solvent. Coexistence of Ag(2)O and silver stearate induces their simultaneous transformation to the silver form at temperatures below 160 degrees C. (c) 2009 The Japan Society of Applied Physics
Microstructures and microwave dielectric properties of Li2O-Nb2O5-ZrO2 ceramics
(2007)
Lu, Chun-An
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Lin, Pang
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Wang, Sea-Fue
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材料科學與工程學系
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Department of Materials Science and Engineering
Solid solution of Li1-4y-xZry+4xNb1-3xO3 system is anew non-stoichiomettic compound with orthorhombic perovskite structure. In this study, the effects of the calcination and the sintering temperatures on the microstructural evolution and microwave dielectric properties of Li1-4y-xZry+4xNb1-3xO3 ceramics were performed. Dense Li0.774Zr0.057NbO3 ceramics can be obtained at the sintering temperature of 1150 degrees C. Li0.774Zr0.057NbO3 phase exists as the main phase with the existence of a minor LiNb3O8 phase. Typical microwave dielectric properties for dense Li0.774Zr0.057NbO3 ceramics are as followed: epsilon(r) approximate to 39, Q x f approximate to 4500, and tau(f) = -16.6 ppm/degrees C, measured at 6 GHz. (c) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.