Browsing by Author "Chang, Yu-Chen"

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A Fully-Integrated Ka-Band 4TX/4RX Phased-Array Transceiver IC in 65nm CMOS
(2016)
Chu, Ching-Yun
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Tseng, Shao-Ting
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Gao, Jing-Zhi
;
Chen, Yuan-Pu
;
Chang, Yu-Chen
This paper presents a fully-integrated Ka-band 4RX/4TX phased-array transceiver IC. The four transceiver channels are synchronized by an I/Q standing wave oscillator (SWO). Their signal phases are shifted by hybrid analog IF and LO phase interpolators, and can be controlled digitally and independently. The SWO further composes an on-chip PLL, and is locked to a 1.09 GHz off-chip global reference to scale to a large array at board level. Each receiver channel achieves 66 dB maximum conversion gain and 4.4 dB minimum noise figure. Each transmitter channel achieves 18 dBm maximum output power. The chip is mounted on a high-frequency laminate, inside which embedded cables connect its RF pads to Vivaldi antennas also inside the same PCB. With the PCB, each channel achieves 360 degrees phase shifting capability under a maximum calibrated 3.7 degrees phase errors. The PCB module presents successful beam steering with 23 degrees measured four-channel 3-dB beamwidth. This chip consumes a peak 5 W power at transmit mode, and is fabricated in TSMC 65nm CMOS technology with a 4 x 2.5 mm(2) chip area.
Core-Shell Pd9Ru@Pt on Functionalized Graphene for Methanol Electrooxidation
(2018-01-01)
Kuo, Chih-Chia
;
Chou, Shih-Cheng
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Chang, Yu-Chen
;
Hsieh, Yi-Chieh
;
Wu, Pu-Wei
A simple but effective electrochemical route to functionalize graphene is demonstrated. Cyclic voltammetric sweeps (CV) are performed in a 0.5 M H2SO4 aqueous solution on electrodes consisting of carbon cloth, graphene, and Nafion ionomer. Upon exposure to ambient oxygen, the formation of hydroxyl radicals from the oxygen reduction reaction during the CV cycles initiates the decomposition of the Nafion ionomer, which produces oxygenated functional groups on the graphene surface. Using contact angle measurements and X-ray photoelectron spectroscopy, various amounts of Nafion ionomer are explored to determine the optimum conditions for graphene functionalization. Afterwards, Pd9Ru nanoparticles with an average size of 3-4 nm are synthesized and impregnated on functionalized graphene (FGN). To prepare core-shell electrocatalysts, Pd9Ru/FGN is subjected to Cu underpotential deposition followed by a galvanic displacement reaction to deposit a Pt monolayer on the Pd9Ru surface (Pd9Ru@Pt). The assynthesized sample (Pd9Ru@Pt/FGN) exhibits enhanced performance in methanol electrooxidation, which includes abetter activity and lower susceptibility to poisoning by intermediates. The electrochemically active surface area (ECSA) of Pd9Ru@Pt/FGN shows a value that is 1.5-fold larger than that of Pd9Ru@Pt on untreated graphene (Pd9Ru@Pt/GN). In the durability tests, Pd9Ru@Pt/FGN and Pd9Ru@Pt/GN demonstrate losses in the ECSA of 14.9% and 30.3%, respectively. (C) 2018 The Electrochemical Society.
Geometrical impact on the optical polarization of droplet epitaxial quantum dots
(2012-09-17)
Liao, Yu-Huai
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Liao, Chien-Chih
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Ku, Chih-Hao
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Chang, Yu-Chen
;
Cheng, Shun-Jen
We report on experimental and theoretical investigations of the optical anisotropy of GaAs/AlGaAs quantum dots grown by droplet epitaxy. With in situ annealing in the growth, the shape of quantum dots is systematically controlled from a tall and laterally symmetric shape to a flat and laterally elongated one. Photoluminescence spectroscopy demonstrates an uncommon observation: the more elongated the quantum dots, the lower the degree of linear polarization. Theoretical analysis based on a four-band k center dot p theory reveals a substantial impact of vertical confinement on the valence heavy-hole and light-hole mixing, which leads to the enhancement of polarization anisotropy for taller quantum dots. The influence of Coulomb interactions on polarization anisotropy is studied by using the partial configuration interaction method, and is shown to reduce the polarization anisotropy through the mixing of single-particle configurations with different symmetries.
Late-news student poster: Wide viewing angle 3D depth-fused display (DFD) system
(2008)
Hsu, Ching-Yi
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Huang, Yi-Pai
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Chang, Yu-Chen
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Ding, Zhi-Hong
;
Su, Chih-Ping
Viewing angle caused by images shift is the most serious issue for depth-fused display (DFD). A wide viewing angle 3D-DFD system utilized high collimated backlight with wide viewing angle micro-lens array was proposed to avoid the images shift From the experiment results, the viewing angle was demonstrated to be increased to 0 = 30 degrees similar to +/- 40 degrees, which is much wider than that of conventional DFD (theta <+/- 10 degrees). Consequently. the proposed 3D-DFD system will be glasses-less, fatigue-less, and wide viewing.
Novel depth-fused display (DFD) system with wide viewing 3D images
(2008)
Hsu, Ching-Yi
;
Huang, Yi-Pai
;
Chang, Yu-Chen
;
Su, Chih-Ping
;
光電工程學系
Viewing angle caused by images shift is the most serious issue for depth-fused display (DFD). A wide viewing angle 3D-DFD system utilized high collimated backlight with wide viewing angle micro-lens array was proposed to avoid the images shift. From the experiment results, the viewing angle was demonstrated to be increased to theta = +/-30 degrees similar to +/-40 degrees, which is much wider than that of conventional DFD (theta<+/-10 degrees). Consequently, the proposed 3D-DFD system will be glasses-less, fatigue-less, and wide viewing.
Rapid Galvanostatic Determination on Levelers for Superfilling in Cu Electroplating
(2010)
Tsai, Ho-Cheng
;
Chang, Yu-Chen
;
Wu, Pu-Wei
;
材料科學與工程學系
;
Department of Materials Science and Engineering
4-Amino-2,1,3-benzothiadiazole and 6-aminobenzo-thiazole were studied as potential levelers for Cu plating in submicrometer trenches. We conducted galvanostatic measurements on rotating disk electrodes at various concentrations and recorded their respective voltages at 200 and 430 rpm. A profile of voltage difference between them at various concentrations revealed a volcano curve in which superfilling was expected to occur for 4-amino-2,1,3-benzothiadiazole but not for 6-aminobenzo-thiazole. Direct scanning electron microscopy observations on the plated Cu confirmed predictions from the volcano curves. A diffusion-adsorption mechanism was proposed for these two compounds to explain their leveling abilities on Cu superfilling. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3265971] All rights reserved.
Synthesis and Characterization of Poly(n-undecyl isocyanate)/Polyaniline Polyblend
(2010-07-05)
Li, Yu-Jen
;
Ho, Ko-Shan
;
Lo, Wan-Ting
;
Yang, Shin-Shiao
;
Chao, Liang
Poly(n-undecyl isocyanate) (PUDIC)/n-dodecylbenzenesulfonic acid (DBSA)-doped polyaniline (PANIDBSA) polyblend was prepared and the effect of the H-bonding between these two polymers on the compatibility, conjugation chain length of PANIDBSA, and helixity of PUDIC in the polyblend system were studied. The monomer and polymer were characterized by NMR spectra and the polyblend was analyzed by FTIR, UV-vis spectra, and wide-angle X-ray diffraction. It was found when the blend composition of the PUDIC was higher than 10%, the WAXD patterns demonstrated lower angle shifting for the peaks at around 2 theta = 2-2.5 degrees, referring to the distance between the layers of the layered structure of PANIDBSA crystalline with increasing PUDIC, indicating the expansion of the layered structure of PANIDBSA. The FTIR spectra illustrated the presence of an absorption peak at 1700 cm(-1) shift to higher wave number with PUDIC due to its H-bonding with PANIDBSA. The UV-vis spectra of PANIDBSA described a blue-shift of the lambda(max) with PUDIC, indicating that the presence of PUDIC in the polyblend system can interrupt and decrease the conjugation chain length of PANIDBSA. The optical activity of the helical PUDIC decreased notably with the presence of PANIDBSA, resulting from the reversed helical effect (de-nature) of H-bonding. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1-7, 2010