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101.
Kyung-Hoon Lim Gunhyun Ahn Sungchan Jung Hyun-Chul Park Min-Su Kim Ju-Ho Van Hanjin Cho Jong-Hyuk Jeong Cheon-Seok Park Youngoo Yang 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2009,56(4):265-269
In this brief, we present a 60-W power amplifier that is linearized using an RF predistorter for multicarrier wideband code-division multiple-access (WCDMA) applications. The proposed RF predistorter is fully composed of RF or analog circuits, and it has a moderate memory effect compensation capability using a delayed third-order intermodulation (IM3) component path. It also includes the IM5 generation circuits and a compact IM3 generator that is capable of autocanceling for the fundamental component. The proposed RF predistorter was implemented and applied to a 60-W high-power WCDMA amplifier. For a four-carrier downlink WCDMA signal, the RF predistorter improved the adjacent channel leakage power ratio at a 5-MHz offset by 6.19 dB at an average output power of 48 dBm. The total efficiency of the system is as high as 13.6% at the same output power level. At an output power level of 60 W, the linearized power amplifier complies with the linearity specification of the WCDMA system. 相似文献
102.
In this paper, we present a method for reconstructing a surface mesh animation sequence from point cloud animation data. We mainly focus on the articulated body of a subject — the motion of which can be roughly described by its internal skeletal structure. The point cloud data is assumed to be captured independently without any inter‐frame correspondence information. Using a template model that resembles the given subject, our basic idea for reconstructing the mesh animation is to deform the template model to fit to the point cloud (on a frame‐by‐frame basis) while maintaining inter‐frame coherence. We first estimate the skeletal motion from the point cloud data. After applying the skeletal motion to the template surface, we refine it to fit to the point cloud data. We demonstrate the viability of the method by applying it to reconstruct a fast dancing motion 相似文献
103.
Cu electroplating which emerges as a viable Cu filling technique for damascene processing relies on the presence of a smooth and continuous Cu seed layer. Metal organic chemical vapor deposition (MOCVD) may be the most promising technique to deposit the Cu seed layer. Plasma pretreatment is widely used as a precleaning technique which is essential for the enhancement of Cu nucleation in Cu-MOCVD. New pretreatment techniques which can replace plasma pretreatments are proposed in this paper. Pd sputtering, Pd–HF dipping or Pd-CVD pretreatment will possibly enhance Cu nucleation significantly if it is conducted on barrier metal films prior to Cu-MOCVD. It was found that Pd sputtering is more effective in enhancing Cu nucleation than direct plasma H2 precleaning. Pd sputtering pretreatment is effective for a variety of barrier metals including Ta, TiN, TaN and TaSiN. The mechanism through which Cu nucleation is enhanced may be as follows: a thin Pd buffer layer formed by sputtering shields the barrier metal substrate surface with adsorbed oxygen atoms making Cu nucleation difficult and provides preferred sites for Cu nucleation. 相似文献
104.
105.
Yurou Zhang Dohyung Kim Jung-Ho Yun Jongchul Lim Min-Cherl Jung Xiaoming Wen Jan Seidel Eunyoung Choi Mu Xiao Tengfei Qiu Miaoqiang Lyu EQ Han Mehri Ghasemi Sean Lim Henry J. Snaith Jae Sung Yun Lianzhou Wang 《Advanced functional materials》2021,31(50):2105542
Organometal perovskite single crystals have been recognized as a promising platform for high-performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal-based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet-controlled cuboid MAPbI3 (MA = CH3NH3+) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs-Pb-rich nanoislands is constructed on the surface of the MAPbI3 single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm2 V−1 s−1. As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high-quality perovskite single-crystal surface for optoelectronic applications. 相似文献
106.
Qing Yang Alvin Lim Shuang Li Jian Fang Prathima Agrawal 《Mobile Networks and Applications》2010,15(1):36-60
Multi-hop vehicle-to-vehicle communication is useful for supporting many vehicular applications that provide drivers with
safety and convenience. Developing multi-hop communication in vehicular ad hoc networks (VANET) is a challenging problem due
to the rapidly changing topology and frequent network disconnections, which cause failure or inefficiency in traditional ad
hoc routing protocols. We propose an adaptive connectivity aware routing (ACAR) protocol that addresses these problems by
adaptively selecting an optimal route with the best network transmission quality based on statistical and real-time density
data that are gathered through an on-the-fly density collection process. The protocol consists of two parts: 1) select an
optimal route, consisting of road segments, with the best estimated transmission quality, and 2) in each road segment of the
chosen route, select the most efficient multi-hop path that will improve the delivery ratio and throughput. The optimal route
is selected using our transmission quality model that takes into account vehicle densities and traffic light periods to estimate
the probability of network connectivity and data delivery ratio for transmitting packets. Our simulation results show that
the proposed ACAR protocol outperforms existing VANET routing protocols in terms of data delivery ratio, throughput and data
packet delay. Since the proposed model is not constrained by network densities, the ACAR protocol is suitable for both daytime
and nighttime city VANET scenarios. 相似文献
107.
Electrically small spiral ground planes for a monopole and an electrically small antenna have been designed for HF ground wave transmission. Prototype ground planes have been built and tested. For the monopole, the transmission loss of the designed ground plane is 6 dB better than that of the same size ground radials. For the electrically small antenna, the transmission loss of the designed ground plane is 7 dB better than that of the same size solid ground plane at the antenna's operating frequency. 相似文献
108.
Ya Jun Yu Yong Ching Lim 《IEEE transactions on circuits and systems. I, Regular papers》2007,54(10):2330-2338
In this paper, a novel optimization technique is proposed to optimize filter coefficients of linear phase finite-impulse response (FIR) filter to share common subexpressions within and among coefficients. Existing approaches of common subexpression elimination optimize digital filters in two stages: first, an FIR filter is designed in a discrete space such as finite wordlength space or signed power-of-two (SPT) space to meet a given specification; in the second stage, an optimization algorithm is applied on the discrete coefficients to find and eliminate the common subexpressions. Such a two-stage optimization technique suffers from the problem that the search space in the second stage is limited by the finite wordlength or SPT coefficients obtained in the first stage optimization. The new proposed algorithm overcomes this problem by optimizing the filter coefficients directly in subexpression space for a given specification. Numerical examples of benchmark filters show that the required number of adders obtained using the proposed algorithm is much less than those obtained using two-stage optimization approaches. 相似文献
109.
Jae‐Hyung Lee Ji‐Hong Kim Gyu‐Ho Lim Tae‐Hoon Kim Jung‐Hwan Lee Kyung‐Hwan Park Mu‐Hun Park Pan‐Bong Ha Young‐Hee Kim 《ETRI Journal》2008,30(3):347-354
In this paper, the design of a low‐power 512‐bit synchronous EEPROM for a passive UHF RFID tag chip is presented. We apply low‐power schemes, such as dual power supply voltage (VDD=1.5 V and VDDP=2.5 V), clocked inverter sensing, voltage‐up converter, I/O interface, and Dickson charge pump using Schottky diode. An EEPROM is fabricated with the 0.25 μm EEPROM process. Power dissipation is 32.78 μW in the read cycle and 78.05 μW in the write cycle. The layout size is 449.3 μm × 480.67 μm. 相似文献
110.
C.W. Jeong D.H. Kang D.W. Ha Y.J. Song J.H. Oh J.H. Kong J.H. Yoo J.H. Park K.C. Ryoo D.W. Lim S.S. Park J.I. Kim Y.T. Oh J.S. Kim J.M. Shin Jaehyun Park Y. Fai G.H. Koh G.T. Jeong H.S. Jeong Kinam Kim 《Solid-state electronics》2008,52(4):591-595
We evaluated the limit of scaling bottom electrode contact (BEC) heater size and high resistivity heater to reduce writing current. It was found that the resistivity of heater should be increased for reducing writing current below the heater size of about 50 nm without any undesirable increase of resistance of the crystalline state (SET state, Rset). It was shown in the numerical simulations that the dissipated heat loss through BEC during melting GST was decreased in the increase of resistivity of heater. In addition, we analyzed the resistance components contributing to the total set resistance. It was observed that the undesired sharp increase of Rset as the BEC size decreases below 50 nm was attributed to the resistance component of GST–BEC interface. In the case of high resistivity heater, the contributions of both incomplete crystallization and heater itself were enhanced. 相似文献