Browsing by Author "Wang, HW"

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A digital LVDS driver with simultaneous switching noise rejection
(2004)
Wang, HW
;
Lu, HW
;
Su, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a Digitized LVDS Driver with SSN (Simultaneous switching noise) rejection is proposed, which is fabricated by TSMC 0.18um CMOS technology. First, the power consumption and chip area are greatly decreased due to the design of digitized driver but we suffered the SSN noise. Second, the method which modifies the driver's control signal greatly reduces the ground bounce, and simultaneously solved the ground bound problem mentioned above. Third, the driver can calibrate the output differential mode by the control signal outside the chip by way of the controllable driver. According to the simulation results, ground bounce reduced from 175mV to 95mV, 55% diminished, and the measurement output jitter (pk-pk) is less than 48ps @1.25Gbps. The driver area is only 210um x 210um and power consumption is less than 19mW, which are extremely lower then the conventional LVDS Driver. The proposed programmable driver can also be applied to the 1.5Gbps Serial ATA standard or 2.5Gbps PCI-Express.
A two-stage up-convertor made of AgGaSe2 and beta-BBO crystals
(2000-01-01)
Wang, HW
;
Lu, MH
;
光電工程學系
;
Department of Photonics
A two-stage infrared up-convertor made of AgGaSe2 and beta-BBO crystals has been built up, that can up-convert the mid-infrared radiation of 11-16 mu m into the 0.8-mu m range where the sensitive photomultiplier can be used. This up-convertor is pumped with a near-infrared radiation of 1.7-1.8 mu m wavelength range generated by a beta-BBO optical parametric oscillator. In this experiment, we also measured the o-ray refractive index of AgGaSe2 in the 11-16 mu m mid-infrared range and extended the fitting range of the Sellmeier equation to the 16-mu m wavelength range.
Barrier layer effect of titanium-tungsten on the electromigration in sputtered copper films on polyimide
(2000-02-01)
Wang, HW
;
Chiou, BS
;
電子物理學系
;
電子工程學系及電子研究所
;
Department of Electrophysics
Titanium-tungsten is employed as the diffusion barrier in a Cu/barrier/polyimide/Si system. The electromigration damage (EMD) of Cu with a TiW barrier is investigated utilizing an empirical formula. Two activation energies are obtained suggesting a surface electromigration mechanism at low temperature (140-190 degrees C) and a combined migration mechanism at high temperature (190-230 degrees C). The presence of the TiW barrier layer improves the high temperature electromigration resistance. The effects of the TiW barrier on the microstructure and electrical properties of Cu metallization are discussed.
Characterization of BaPbO3 and Ba(Pb1-xBix)O-3 thin films
(2002-02-17)
Sun, CL
;
Wang, HW
;
Chang, MC
;
Lin, MS
;
Chen, SY
BaPbO3 and Ba(Pb1-xBix)O-3 films made from barium 2-ethylhexanoate, lead 2-ethylhexanoate and bismuth acetate were prepared by metal-organic deposition (MOD) method on Pt/Ti/SiO2/Si substrate. The phase transition and the physical properties of these films were studied. The polycrystalline BaPbO3 phase starts to form above 600 degreesC and the Pb-excess addition would enhance the formation of single perovskite BaPbO3 phase. With increasing annealing temperature, the optimum sheet resistance 1.6 Omega sq(-1) (resistivity approximate to 1.07 x 10(-4) Omega cm) could be obtained at 750 degreesC. However, an annealing temperature over 800 degreesC causes reactions between substrate and BaPbO3 phase and results in sharp increase of resistance. On the other hand, the substitution of Pb by Bi in the Ba(Pb1-xBix)O-3 films could stabilize the perovskite phase, though the sheet resistance is raised over 10 Omega sq(-1) at x = 0.3. (C) 2002 Elsevier Science B.V. All rights reserved.
Characterization of BaPbO3 and Ba(Pb1-xBix)O-3 thin films
(2003-02-17)
Sun, CL
;
Wang, HW
;
Chang, MC
;
Lin, MS
;
Chen, SY
BaPbO3 and Ba(Pb1-xBix)O-3 films made from barium 2-ethylhexanoate, lead 2-ethylhexanoate and bismuth acetate were prepared by metal-organic deposition (MOD) method on Pt/Ti/SiO2/Si substrate. The phase transition and the physical properties of these films were studied. The polycrystalline BaPbO3 phase starts to form above 600 degreesC and the Pb-excess addition would enhance the formation of single perovskite BaPbO3 phase. With increasing annealing temperature, the optimum sheet resistance 1.6 Omega sq(-1) (resistivity approximate to 1.07 x 10(-4) Omega cm) could be obtained at 750 degreesC. However, an annealing temperature over 800 degreesC causes reactions between substrate and BaPbO3 phase and results in sharp increase of resistance. On the other hand, the substitution of Pb by Bi in the Ba(Pb1-xBix)O-3 films could stabilize the perovskite phase, though the sheet resistance is raised over 10 Omega sq(-1) at x = 0.3. (C) 2002 Elsevier Science B.V. All rights reserved.
Electrical properties of Mg/La, Mg/Nb co-doped (Ba0.7Sr0.3)TiO3 thin films prepared by metallo-organic deposition method
(2001-08-01)
Chen, SY
;
Wang, HW
;
Huang, LC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba0.7Sr0.3)TiO3 (BST) thin films doped with La, Nb and Mg ions along with an Mg/La, Mg/Nb codopant were prepared on Pt/Ti/SiO2/Si substrates by the metal-organic deposition method. A decrease of grain size, dielectric constant, and leakage current with increasing doping levels was observed for all studied cases. The grain size, dielectric constant and leakage current increased with increasing annealing temperatures for specimens doped with a single dopant. However, the leakage current was reduced to a minimum for the codoped materials at the donor/acceptor compensated concentration and decreased with increasing annealing temperatures. The decreased leakage current of the codoped materials could be explained by the additional barrier height and width of the insulating layer caused by the defect dipoles around grain boundaries.
Electromagnetic wave absorption behavior of NiZn-ferrite prepared via hydrothermal method
(2005)
Peng, CH
;
Wang, HW
;
Kan, SW
;
Chen, SY
;
材料科學與工程學系
Ni0.5Zn0.5Fe2O4 ferrite powders were synthesized by a hydrothermal method. The nanoparticles of these materials were mixed with a thermal-plastic polyurethane (TPU) polymer in order to form a suitable composite for electromagnetic wave absorber in a frequency range from 2.0 to 15.0 GHz. The effect of particle size on the reflection loss was investigated by comparing nanosized and microsized powders. The reflection loss as a function of frequency (f), thickness of the absorber(d), the real and imaginary part of permittivity (epsilon' / epsilon") and the real and imaginary part of permeability (mu'/mu") were obtained by calculation using the Bruggeman effective medium theory. The effect of Co2+, Cu2+, and Mg2+ on the reflection loss was also studied.
Electromigration in sputtered copper films on polyimide
(1999-06-01)
Wang, HW
;
Chiou, BS
;
Jiang, JS
;
電子物理學系
;
電子工程學系及電子研究所
Electromigration damage (EMD) is one of the major causes for the failures of interconnects. In this study, the electromigration of Cu on polyimide is investigated. An empirical formula is used to evaluate the EMD of Cu film. The activation energy (Q) obtained is significantly less than those of lattice and grain boundary diffusion. This suggests that the electromigration in copper proceeds via an interfacial diffusion path. The geometry of the metallization also affects the activation energy. Any abrupt change in the interconnect direction and metal width causes current crowding and should be avoided. The current exponents (n), calculated from EMD data, are 3.58 and 3.35 for straight and zig-zag Cu films, respectively.
Electromigration in sputtered copper interconnection with polyimide as interlevel dielectric or passivation
(2000)
Chiou, BS
;
Jiang, JS
;
Wang, HW
;
Hung, HY
;
電子工程學系及電子研究所
Electromigration damage (EMD) is one of the major causes for the failures of interconnection. The use of copper and low dielectric constant dielectric has been proposed to reduce the RC time delay and to improve EMD. In this study, the Electromigration of Cu with polyimide is investigated with an empirical formula dR/dt.1/R-0 = AJ(n) exp(-Q/RT). Secondary ion mass spectrometry (SIMS) reveals the interdiffusion between Cu and polyimide during curing of the polyimide and/or annealing of Cu metallization. Thin layers of TiW is deposited between polyimide and Cu as a barrier to reduce the interdiffusion. The activation energy Q for the electromigration of Cu on polyimide is 0.77eV from 120 degrees C to 230 degrees C, while activation energies for samples with titanium tungsten as an interlayer are 0.79eV (140 degrees C to 190 degrees C) and 1.73eV (190 degrees C to 230"C). The presence of TiW barrier enhances the high temperature electromigration resistance and promotes the adhesion between Cu and polyimide interface. However, films with TiW are found to be more sensitive to current stressing than those without. Polyimide is also employed as a passivated layer on top of Cu metallization. Resistance of the passivated samples decrease in the initial stage of the electromigration experiment. Possible causes are discussed on the decrease in R. The geometry of the metallization also affects the electromigration, the current exponent (n), calculated from EMD data, are different for interconnection with different geometries.
Low-temperature synthesis of transition metal nanoparticles from metal complexes and organopolysilane oligomers
(2002-10-01)
Chang, YH
;
Wang, HW
;
Chiu, CW
;
Cheng, DS
;
Yen, MY
Mo, W, and Cu nanoparticles (5-50 nm) are synthesized from reactions employing a metal complex, such as MoO2Cl2(DME), MoCl5, WCl6, ((CuOBu)-Bu-t)(4), or CuCl2, and a organopolysilane oligomer Si(SiMe3)(4) or (SiMe2)(6) either in a hexane solution (343 K) or in a sealed tube (473-673 K). Oxo- and chlorophilicities of the silyl groups provide for an energetically favored reaction route to reduce the metal complexes. The reaction byproducts are removed easily either by evaporation or dissolution into hydrocarbon solvents. It is proposed that the homogeneous mixing of the reactants in vapor and solution phases allows the association and growth of molecules into small clusters, then into nanosized metal particles.
Microwave absorbing materials using Ag-NiZn ferrite core-shell nanopowders as fillers
(2004-12-01)
Peng, CH
;
Wang, HW
;
Kan, SW
;
Shen, MZ
;
Wei, YM
Silver nanoparticles coated with Ni0.5Zn0.5Fe2O4 spinel ferrites, forming a core-shell structure, were synthesized by utilizing hydrothermal method at different ferrite/silver ratio (ferrite/silver = 6/1, 4/1, 2/1, 1/1, 1/6) and introduced into polyurethane matrix to be a microwave absorber. The complex permittivity (epsilon', epsilon") and permeability (mu', mu") of absorbing composite materials consisted of ferrite/silver core-shell nanopowders and polyurethane were measured in the frequency range of 2-15 GHz. The reflection loss and matching frequency were calculated from measured data using theory of the absorbing wall for different ferrite/silver ratios. It was found that the matching frequency for reflection loss exceeded a satisfactory -25dB at 9.0 GHz for using NiZn ferrite as a filler shifts to higher frequencies (10.9-13.7 GHz) as the ferrite/silver ratio of core-shell nano-filler decreased from 6/1 to 2/1. The present result demonstrates that microwave absorbers using ferrite/silver core-shell filler can be fabricated for the applications over 9 GHz, with reflection loss more than-25 dB for specific frequencies, by controlling the ferrite/silver ratio of the core-shell nano-fillers in the composites. (C) 2004 Elsevier B.V. All rights reserved.
Pilot-symbol assisted channel estimation for coherent DS-CDMA communications
(2000)
Wang, HW
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Coherent uplink detection of an asynchronous CDMA terrestrial radio system is feasible with a pilot-assisted channel estimation. In this paper, we present an interpolated M-slot averaging scheme for pilot-symbol assisted channel estimation. The M-slot averaging samples are input to a Lagrange interpolator to obtain the desired channel estimates. The hardware of this new scheme is simpler than the modified weighted multi-slot averaging (WMSA) estimation filter [6] with comparable tracking ability.
Role of an intermediate phase (Ba,Sr)(2)Ti2O5CO3 in doped (Ba0.7Sr0.3)TiO3 thin films
(2003-01-30)
Chen, SY
;
Wang, HW
;
Huang, LC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba0.7Sr0.3)TiO3 (BST) thin films doped with La, Nb, and Mg ions were prepared by metal-organic deposition method (MOD) on Pt/Ti/SiO2/Si substrates. An intermediate phase formed under an annealing temperature of 550-650 degreesC, and disappeared at higher temperatures during the formation of BST. The intermediate phase was analyzed by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and Raman spectra and found to be an oxycarbonate with a chemical formula of (Ba,Sr)(2)TiO5CO3. The stability of this intermediate phase increased with the addition of dopants, irrespective of doping types. It is proposed that distortion of crystal structure, physical constraint in the two-dimensions and small grain size favor the existence of poor crystallized (Ba,Sr)(2)Ti2O5CO3. (C) 2002 Elsevier Science B.V. All rights reserved.
Self-generated NAF nano template assisted formation of porous carbon nanotube arrays.
(2004-03-28)
Chiu, HT
;
Huang, CH
;
Chang, YH
;
Lee, CY
;
Cheng, SF
The electromagnetic wave absorbing characteristics of MnZn ferrite-TPU composite materials
(2005)
Peng, CH
;
Wang, HW
;
La, YT
;
Chen, SY
;
材料科學與工程學系
The complex permeability and permittivity (mu(r)*and epsilon(r)*) were investigated for MnZn ferrite-TPU (thermal-plastic polyurethane) composite with ferrite weight percentage varying from 66.7%-88.9%. Fine ferrite powders doped with Mg, Co, and Cu prepared by the citrate gel route were used as fillers. The effective complex permeability and permittivity specta in composites with various ferrite weight percentage were calculated using the Bruggeman effective medium theory. It was found that the dopant content and ferrite/TPU ratio influences the microwave-absorbing characteristics. The results show that the absorbers with (Mg, Co, Cu) doped ferrite have excellent electromagnetic absorption. The reflection loss more than 20dB at the frequencies below 3 GHz can be achieved by controlling the ferrite content and doped elements in the ferrite-TPU composites.
The observation of the competition and suppression for stimulated Raman scattering near the potassium 4S-5P resonance
(2000-11-28)
Wang, HW
;
Lu, MH
;
光電工程學系
;
Department of Photonics
The competition of stimulated Raman scattering (SRS) between 4S-(5P)-5S and 4S-(3D)-5S channels has been observed as a laser is tuned near the 4S-5P resonance in potassium vapour. The experimental results show that SRS only occurs in the 4S-(5P)-5S channel. In this Raman scattering, suppression of the amplified spontaneous emission (ASE) (5S-4P) has been observed, The influence of the four-wave mixing (FWM) processes on the SRS is discussed. In the 4S-(5P)-3D channel, in the backward direction no detectable emission corresponding to SRS (4S-(5P)-3D) has been observed, so the forward (5P)-3D emission should be FWM, not SRS. The ASE (3D-4P) arises from the ASE (5P-3D), which can be observed in the backward direction.
The refractive index of extraordinary ray for AgGaSe2 crystal in 11-16 mu m range
(2001-06-01)
Wang, HW
;
Lu, MH
;
光電工程學系
;
Department of Photonics
The refractive index of AgGaSe2 for extraordinary ray in the 11-16 mum mid-infrared range was measured and an improved Sellmeier equation from 0.85 to the 16 mum wavelength range is proposed. In this experiment, the mid-infrared radiations of the 11-16 mum wavelength range were mixed with a near-infrared radiation of the 1.7-1.8 mum wavelength range in AgCaSe2 crystal in type II. With the measurement of phase-matching angles the refractive index for extraordinary ray was calculated. The near-infrared radiation was produced by a beta -BBO optical parametric oscillator. (C) 2001 Elsevier Science B.V. All rights reserved.