A 3.3-V single power supply 16-Mb nonvolatile virtual DRAM using aNAND flash memory technology

A 3.3-V 16-Mb nonvolatile memory having operation virtually identical to DRAM with package pin compatibility has been developed. Read and write operations are fully DRAM compatible except for a longer RAS precharge time after write. Fast random access time of 63 ns with the NAND flash memory cell is achieved by using a hierarchical row decoder scheme and a unique folded bit-line architecture which also allows bit-by-bit program verify and inhibit operation. Fast page mode with a column address access time of 21 ns is achieved by sensing and latching 4 k cells simultaneously. To allow byte alterability, nonvolatile restore operation with self-contained erase is developed. Self-contained erase is word-line based, and increased cell disturb due to the word-line based erase is relaxed by adding a boosted bit-line scheme to a conventional self-boosting technique. The device is fabricated in a 0.5-μm triple-well, p-substrate CMOS process using two-metal and three-poly interconnect layers. A resulting die size is 86.6 mm², and the effective cell size including the overhead of string select transistors is 2.0 μm²     

Quantitative Evaluation Method for Etch Sidewall Profile of Through‐Silicon Vias (TSVs)

Through‐silicon via (TSV) technology provides much of the benefits seen in advanced packaging, such as threedimensional integrated circuits and 3D packaging, with shorter interconnection paths for homo‐ and heterogeneous device integration. In TSV, a destructive cross‐sectional analysis of an image from a scanning electron microscope is the most frequently used method for quality control purposes. We propose a quantitative evaluation method for TSV etch profiles whereby we consider sidewall angle, curvature profile, undercut, and scallop. A weighted sum of the four evaluated parameters, nominally total score (TS), is suggested for the numerical evaluation of an individual TSV profile. Uniformity, defined by the ratio of the standard deviation and average of the parameters that comprise TS, is suggested for the evaluation of wafer‐to‐wafer variation in volume manufacturing.     

Performance evaluation and application of channel offset schemes inindoor channel assignments

We deal with channel offset schemes and their application in three-dimensional (3-D) frequency reuse environments with ideal cubic microcells. Formulas are derived to calculate channel reuse distances (CRDs) and interchannel usage distances (IUDs) for a given offset degree. For an indoor personal communication network (PCN), an algorithm is proposed for fixed channel assignment with channel offset. The spectral efficiency of channel offset schemes is discussed and the results show that compared to the channel offsetless scheme, channel offset schemes make more efficient use of limited spectrum resources     

Power generation characteristics of a sandwich‐type self‐heating thermoelectric generator with spatially varying embedded heat source

Power generation characteristics of a sandwich‐type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device. Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Modeling and simulation of 2D lithium‐ion solid state battery

The goal of the work presented here was to develop a simulation approach for studying the effects of materials and geometry on the performance of Li‐ion Solid State Batteries (SSB). Simulation provides the opportunity to explore, with ease, different material properties and cell geometries to optimize a Li‐ion SSB's performance. Simulations shown in this paper are time‐dependent and consider electrochemical reaction, heat transfer, the diffusion of Li‐ions and electrons in the electrolyte, and solid Li diffusion in the positive electrode. A 2D model was simulated and the results shown. The simulations were able to show discharge curves, heat flux, the concentration of Li‐ions, electrons, and solid Li at any time in the discharge cycle. Copyright © 2015 John Wiley & Sons, Ltd.     

Ultra fast symmetry and SIMD-based projection-backprojection (SSP) algorithm for 3-D PET image reconstruction

Remarkable progress in positron emission tomography (PET) development has occurred in recent years, in hardware, software, and computer implementation of image reconstruction. Recent development in PET scanners such as the high-resolution research tomograph (HRRT) developed by CTI (now Siemens) represents such a case and is capable of greatly enhanced resolution as well as sensitivity. In these PET scanners, the amount of coincidence line data collected contains more than 4.5 x 10(9) coincidence lines of response generated by as many nuclear detectors as 120 000. This formidable amount of data and the reconstruction of this data set pose a real problem in HRRT and have also been of the major bottle neck in further developments of high resolution PET scanners as well as their applications. In these classes of PET scanners, therefore, obtaining one set of reconstructed images often requires many hours of image reconstruction. For example, in HRRT with full data collection in a normal brain scan (using SPAN 3), the image reconstruction time is close to 80 min, making it practically impossible to attempt any list-mode-based dynamic imaging since the image reconstruction time would take many days (as much as 43 h or more for 32-frame dynamic image reconstruction). To remedy this data-handling problem in image reconstruction, we developed a new algorithm based on the symmetry properties of the projection and backprojection processes, especially in the 3-D OSEM algorithm where multiples of projection and back-projection are required. In addition, the single-instruction multiple-data (SIMD) technique also allowed us to successfully incorporate the symmetry properties mentioned above, thereby effectively reducing the total image reconstruction time to a few minutes. We refer to this technique as the symmetry and SIMD-based projection-backprojection (SSP) technique or algorithm and the details of the technique will be discussed and an example of the application of the technique to the HRRT's OSEM algorithm will be presented as a demonstration.     

一种适用于高数据速率和高速移动环境的新型信道估计方法——双正交通道信道估计方法

本文给出了一种适用于高数据速率和高速移动环境下的新型有效的信道估计方法-双正交通道信道估计方法(CETOC,Channel Estimation by using Two Orthogonal Channels),这种信道估计方法通过采用两个独立通道的联合估计,可以有效的克服快衰落的影响,从而使得在快衰落信道下应用多维状态调制成为可能.     

红外无源定位技术研究

传统的无源定位方法大都采用多个接收机测向 ,交叉定位 ,但其测向精度低 ,难以满足实际需求。基于最小二乘法原理提出的极小化误差法 ,其定位精度大大提高 ,仿真结果表明 ,将此方法用于红外探测阵列具有良好的定位性能。     

恒偏向棱镜的光线变换矩阵和传输特性分析

恒偏向棱镜是指能恒定改变光束传输方向的转向元件。本文分析了恒偏向棱镜,导出了它的光线变换矩阵及失调矩阵,进一步导出了棱镜存在制造公差情况下的变换矩阵,并指出它只是二维失调不灵敏元件。最后分析了它对一般离轴像离散高斯光束的传输变换特性,给出了复曲率和离轴参数的张量变换规律。     

传导型电源干扰的抑制

本文以开关电源为例,分析了电源EMI滤波器的等效电路,并介绍了用于抑制电源线电磁干扰的滤波器的插入损耗的计算方法,为电源EMI滤波器的设计提供了参考.