Novel design for small-size coplanar waveguide frequency tripler

This letter presents a novel design for a small-size coplanar waveguide frequency tripler. In this study, a new BPF has been replaced the conventional stub lines in the output termination of the multiplier. Not only enhance the performance of the tripler, but also reduce the whole circuit size. to 2.125/spl times/2.275 cm/sup 2/ in the frequency 0.8/2.4 GHz, The spurious suppressions are 37.48, 33.38, and 32.08 dBc for the 1st, 2nd, and 4th harmonics, respectively. It reveals the best output power of -1.92 dBm for a 0 dBm input signal and maximum conversion gain of -1.92 dB. It is very useful for applications in the wireless communication and radar systems.     

Algorithms of halftoning color images with edge enhancement

Printers usually generate a limited number of colors and lack the ability of producing continuous-tone color images. Traditional error-diffusion algorithms are used to solve this problem. Compared with other approaches, the approaches of using error-diffusion in general can generate halftoned images of better quality. However, smeared edges and textures may occur in these halftoned images. To produce halftoned images of higher quality, these artifacts due to unstable images, dot-overlap, and error-diffusion must be eliminated or reduced. In this paper, we show that unstable images can be eliminated or reduced through using a proper color difference formula to select the reproduction colors even vector error-diffusion is performed in the RGB domain. We also present a method of using different filters to halftone different components of a color. This approach may have clearer and sharper edges for halftoned color images. Unexpected colors may be generated due to dot-overlap in the printing process. We have presented a method to eliminate this color distortion in the process of error-diffusion. Halftoning a color image by our proposed error-diffusion algorithm with edge enhancement has the following characteristics: the unstable images do not exist; the color-error caused by dot-overlap is corrected; and the smeared edges are sharpened.     

Current Phase Lead Compensation in Single-Phase PFC Boost Converters With a Reduced Switching Frequency to Line Frequency Ratio

Traditional design of the current loop controller in a single-phase power factor correction boost converter is not suitable for applications with higher line frequencies (up to 800 Hz) because of the zero-crossing distortion and high harmonic content due to the current phase lead effect. Increasing the control bandwidth and switching frequency in order to avoid this effect would reduce converter efficiency and is objectionable. The paper presents the leading-phase admittance cancellation (LPAC) technique, which improves the current-shaping control structure and eliminates the current phase lead without increasing the bandwidth requirement. The LPAC method extends the allowable line frequency range from 1/150 to 1/5 of the current loop bandwidth. The LPAC method is load-invariant and superior to other previously proposed methods. The LPAC network can be added to existing designs, which would require only two passive components in the simplest case     

Growth of CdS Nanoneedles by Pulsed Laser Deposition

CdS nanoneedles have been grown on Ni-coated Si (100) substrates by pulsed laser deposition. Substrate temperature and Ni-catalyst layer thickness were found to have great effects on the density and morphology of the as-grown CdS nanoneedles. Crystalline CdS nanoneedles with middle diameter and length of about 40?nm to 100?nm and 400?nm to 1000?nm, respectively, could be obtained at 350°C to 450°C on Ni-coated silicon (100) substrates, and nanoneedles with good shapes were obtained at 400°C substrate temperature. From the cross-section morphologies, it was found that the CdS nanoneedles grew out of the base CdS crystallite layer with thickness of about 500?nm. Based on the experimental results, vapor?Csolid and vapor?Cliquid?Csolid growth modes describe the CdS nanoneedle growth.     

Characteristic of copper wire and transient analysis on wirebonding process

In the present paper, two major analyses are achieved. In the first, experimental procedures were accomplished to measure tensile mechanical properties of copper (Cu) wire (? = 1 mil) before/after electric flame-off (EFO). Characteristics of free air ball (FAB), heat affected zone (HAZ) and thermal stable zone (TSZ) in as-drawn wire have been carefully investigated by microhardness, self-design pull test fixture, nanoindentation and atomic force microscopy (AFM). A 2nd EFO real-time technique has been conducted to reduce the strength of Cu wire and increase the bonding region. Secondary, with the obtained experimental material data, a comprehensive finite element wirebonding model based on explicit time integration software ANSYS/LS-DYNA is developed to predict the overall strain/stress distributions on the aluminum (Al) bond pad. Finite element analysis (FEA) results demonstrate that plastic deformation on Al bond pad around smashed FAB can be reduced by increasing the surface roughness on FAB. A series of comprehensive parametric studies were conducted in this research.     

Optimization of polymer light emitting devices using TiOx electron transport layers and prism sheets

The internal and external efficiency of polymer light emitting devices were found can be simultaneously improved by insertion a high refractive index material, titanium oxide (TiO_x), to the emission layer and a prism sheet attached to the substrate. The TiO_x layer increased the internal efficiency due to a better electron injection and hole confinement. However, it led a wider angular emission profile with more photons trapped in the substrate. By using the prism sheet, those trapped light was efficiently coupled to the air. The extraction efficiency enhancement was increased from 33.1% to 54.4% and the overall current efficiency was improved up to 86%.     

Integrating PSONN and Boltzmann function for feature selection and classification of lymph nodes in ultrasound images

Lymph nodes (LNs), part of the lymphatic system, are important in the proper functioning of the immune system. LN metastasis is an important index for staging malignant tumors. The present study proposes a system that classifies lymph nodes according to pathological change from ultrasound (US) images. Features are selected and extracted from the US images. A feature selection method that integrates the particle swarm optimization neural network (PSONN) with the Boltzmann function is proposed to select significant features. A multi-class support vector machine (SVM) is adopted to classify diseases of the LN in the region of interests (ROIs) of US images into six categories. The experimental results show that the proposed approach decreases the number of selected features and that its classification is highly accurate.     

带约束的复FIR数字滤波器Chebyshev设计算法

本文主要讨论了复FIR数字滤波器的频域不等式约束Chebyshev设计问题.作者首先把文献[1]中的复交错点组定理扩展到有不等式约束的情况,之后根据扩展定理中对最优解特性的描述,并结合复Remez算法[1]及赖晓平的迭代Remez算法[2][3],提出了一种有效的算法来解决频域带不等式约束的复FIR数字滤波器的Chebyshev设计问题.如果问题的解存在,则算法能保证收敛到最优解.作者用MATLAB语言对上述算法进行了实现并做了仿真分析.     

High-powered thermal gel degradation evaluation on board-level HFCBGA subjected to reliability tests

HFCBGA is a thermally enhanced FCBGA with its heat spreader extending the heat conduction area by connecting itself to the rear side of the silicon die. A thermal interface material plays an important role as a heat conduction path. The thermal performance should not only be checked at time zero, and several reliability tests have to be undertaken to uncover the field conditions faced by end users. A temperature cycling test, highly-accelerated temperature and humidity stress test and multiple reflows are utilized to investigate the thermal resistance of junction to case of a selected thermal gel.     

A fractional-N frequency synthesizer for single-chip UHF RFID reader

A novel fractional-N frequency synthesizer which is based on delta sigma modulator (DSM) and specialized for single-chip UHF 860-to-960 MHz band radio frequency identification (RFID) reader is proposed in this paper. The fractional-N synthesizer is implemented in 0.18 μm CMOS process. The phase noise of the fractional-N synthesizer is approximately ?109 and ?129 dBc/Hz at 200 kHz and 1 MHz offset from 900 MHz operating frequency while drawing 9.6 mA from 1.8 V power supply. The synthesizer is evaluated by implementing it in a direct conversion RF front-end. The front-end features a noise figure of 3.5 dB and an input-referred third-order intercept point of 5 dBm.