基于有限状态机模型的光刻版图自动布局系统

采用有限状态机模型设计了集成电路光刻版上各个图形布局的自动系统。将布局的各个阶段定义为不同的状态,布局规则定义为触发条件,组成一个有限状态机。基于此模型的计算机自动布局系统能自动完成图形在光刻版上的布局,充分利用硅圆片面积并给出布局报告。     

Instrumentation for conformable photomask lithography

A vacuum frame and a multiple mask alignment system for conformable photomask lithography are described. These instruments greatly improve the convenience and adaptability of conformable photomask lithography and may permit the advantages of improved resolution, dimensional control, photoresist profile control, and reduced mask damage to be realized in routine photolithographic production.     

光刻版图形处理过程的计算机仿真

采用有限状态机模型来仿真集成电路行业中光刻版图形的处理过程,涵括了层次处理、涨缩处理和反转处理。将不同的处理过程定义为相应的状态,将图形处理要求定义为输入条件触发状态转换。该模型已应用于光刻版数据处理的电子设计自动化软件。     

Improved mapping policy for reducing error coefficient in CPFSK signals

An improved mapping policy is introduced that alternates between standard and inverted bit mapping functions at selected phase states to reduce the error coefficient of continuous phase frequency shift keying (CPFSK) signals. The proposed policy can be applied to many different forms of CPFSK signals. It is demonstrated that the mapping policy can significantly improve performance, particularly at lower to moderate SNR values.     

Optimization of the design and mode of operation of a QD laser for reducing the heat-to-bitrate ratio

Heat dissipation under the high-speed modulation of quantum dot edge-emitting lasers is considered. It is shown that, for a given laser diode, there is a bias current at which the heat-to-bitrate ratio is minimized. Moreover, there exists a certain optimal optical loss of the laser cavity at which the lowest heat-to-bitrate ratio is provided for any design of edge-emitting lasers that can be fabricated from an epitaxial structure. The heat-to-bitrate ratio and the corresponding bitrate are numerically calculated and analytical expressions are derived. It is demonstrated that the heat-to-bitrate ratio of quantum dot edge-emitting lasers can be less than 0.4 pJ/bit at a bitrate exceeding 10 Gbit/s.     

Optimization of WDM lightwave systems (BAC) design using error control coding

In a binary asymmetric channel (BAC) it may be necessary to correct only those errors which result from incorrect transmission of one of the two code elements. In optical fiber multichannel systems, the optical amplifiers are critical components and amplified spontaneous emission noise in the optical amplifiers is the major source of noise in it. The property of erbium doped fiber amplifier is nearly ideal for application in lightwave long haul transmission. We investigate performance of error correcting codes in such systems in presence of stimulated Raman scattering and amplified spontaneous emission noise with asymmetric channel statistics. Performance of some best known concatenated coding schemes is reported.     

用进刀量补偿法减小细长轴车削加工误差

首先分析了细长轴车削加工时造成的位移,理论上分析了误差的大小与位移量的关系,然后运用材料力学公式得出切削点位移量与切削力的关系,又根据径向切削力经验公式获得切削力与进刀量的关系,推出了理论进刀量与实际进刀量的关系,提出了用进刀量补偿法减小细长轴车削加工误差的模型。最后通过试验验证了采用进刀量补偿方法,在不改变机床精度的前提下显著提高细长轴的加工精度。     

Fabrication for metal photomask pattern by using fountain-pen nanolithography

The fabrication of photomask by fountain-pen nanolithography (FPN) with silver nanoparticles ink is studied. The FPN, a kind of pen-type nanolithography technique, enables on-demand patterning of micro-meter size at large area. Firstly preparation of silver nanoparticles ink and patterning condition by FPN were investigated. Then the photomask was fabricated by the FPN with the prepared ink. And photolithography process with the photomask was tried. The result indicates that the pattern made by the FPN behaved as a photomask.     

Optimization of placement by candidate sieving

A new algorithm for standard cell placement problem is presented. It is based on an idea that appropriate step by step reduction of allocatable cells for each component yields a good placement result. This algorithm named candidate sieving is applicable for discrete quadratic assignment problem with some constraint. The results obtained by candidate sieving are compared in terms of wire length and computing time with those obtained by simulated annealing which is considered the most popular method today. In many cases, candidate sieving has yielded shorter wire lengths, which are equal or almost equal to those obtained by simulated annealing, but with much less computing time     

光刻版数据处理中的工艺涨缩问题

介绍了集成电路行业中在光刻版数据处理时的工艺涨缩问题，分别讨论了正涨缩和负涨缩问题，涨缩与反转处理的次序问题，尤其对位于版图边沿图形的涨缩进行了详细的讨论，并且提出了一种电子设计自动化软件的解决方案和实际结果。     

Optimal design and placement of pilot symbols for channel estimation

The problem of designing and placing pilot symbols for the estimation of frequency-selective random channels is considered. The channel is assumed to be a block-fading model with finite impulse response (FIR). For both single-input single-output (SISO) and multiple-input multiple-output (MIMO) channels, under the assumption of independent and identical distributed channel taps, the Cramer-Rao bound (CRB) on the mean square error (MSE) of semi-blind channel estimators is derived and minimized with respect to pilot symbols and their placement. It is shown that the optimal strategy is to place pilot symbols satisfying certain orthogonality condition in such a way that data and pilot symbols with higher power are in the middle of the packet. The results also indicate that the optimal pilot placements are independent of channel probability distribution. For constant modulus symbols, we show that the quasi-periodic placement and its generalization in the multiuser case turn out to be optimal. We further consider estimating channels with correlated taps and show that the previous placement strategy is also optimal among orthogonal pilot sequences.     

A simple mask aligner and printing frame for conformable photomask lithography

Conformable photomask lithography allows submicrometer lines to be replicated by contact printing. Surface acoustic wave devices with 0.4-µm lines have been produced using this technique. A mask aligner and printing frame have been designed which feature micrometer controlledXandYmotion, rotation about the center of the viewing field, and both top and bottom illumination of mask and substrate. The construction and use of the apparatus, which is based on a toolmaker's microscope, is fully described.     

Optimization of the printed circuit boards placement at thermal design of the units with natural air cooling

It is considered an influence of printed circuit boards placement on temperature distribution in electronic equipment units with natural air cooling. Modeling of the temperature distribution in the unit and research of mass-dimension characteristics were carried out by means of CADs and engineering analysis. There are developed simplified geometric and thermal models of the unit. Here we analyze specificities of heat exchange in the units of radio electronic equipment with natural air cooling. It is developed an algorithm for optimization of printed circuit boards placement in radio electronic equipment with natural air cooling taking into account non-uniform power distribution between printed circuit boards. Proposed algorithm can be used as one of the stage of optimization of size, carrying or mass-dimension factors of the unit in case where unit powers are distributed non-uniformly.     

A new design of prefilter for reducing timing synchronization jitter

For high‐precision timing synchronization in feedback Gardner algorithm and different feedforward nonlinear algorithms, timing jitter reduction is the key problem, especially with a small roll‐off factor in high‐order modulation. Through the elaborate analysis about the timing jitter, this paper proposes a new prefilter design method based on finite impulse response structure. Using a suitable Kaiser window for suppressing the sidelobe energy of the proposed prefilter, this method can further decrease the complexity of filter design and eliminate most part of the pattern noise. Compared with the previous prefilter design algorithms, the approach has a better improvement in steady‐state phase jitter reduction without increasing the capture time in Gardner timing error detector. Meanwhile, with such kind of prefilter, the performance of logarithmic nonlinearity is better than that of square law nonlinearity, this is not reported in literature. Simulation results show that the residual timing jitter in both kinds of algorithms is closed to the modified Cramer‐Rao bound when the roll‐off factor is equal to 0.1 in 1024QAM.     

Estimation of the contouring error vector for the cross-coupledcontrol design

In biaxial motion systems, applying the cross-coupled control (CCC) significantly improves contouring accuracy for linear and circular contours. As geometrical and parametric curves become more popular in modern manufacturing, machining processes with multiaxis motion systems are required, however, the available biaxial CCC cannot be directly applied to arbitrary contours with multiaxis machining systems. In this paper, we propose a novel approach for arbitrary contours by estimating the contouring error vector to efficiently determine the variable gains for CCC. Experimental results for a biaxial motion system indicate that the proposed approach efficiently yields variable gains similar to those in traditional CCC. Furthermore, results on a three-axis CNC machining center show that the present approach significantly improves motion accuracy in multiaxis motion systems     

一种降低码构造复杂度的QSTBC设计

本文采用分圆格方法,设计了一种简化型具全分集、满速率特性的四发四收准正交空时分组码。该准正交空时分组码不仅比传统的基于星座调制技术的四发四收准正交空时码具有更大的分集增益上界,而且比已有的八发一收分圆准正交空时码在误码率和信道容量、以及中断概率等方面皆具有显著的优越性。     

Non-unitary precoder design for reducing feedback overhead in MIMO-OFDM systems

The precoder feedback overhead in MIMO-OFDM systems is heavy as the number of subcarriers is usually large. Most of the current limited feedback works focus on unitary precoding schemes. Based on the fact that the channel matrices of neighboring subcarriers in MIMO-OFDM systems are correlated, an alternative transceiver is proposed here. In this paper, non-unitary precoders shared by several adjacent subcarriers, and the corresponding individual equalizers are jointly designed under partial CSI. As the number of precoding matrices is smaller, the feedback overhead can be reduced. The transceivers are designed to minimize the detection mean-squared error (MSE) under the total transmit power constraint. A convergent iterative algorithm based on the Lagrange multipliers method is proposed. The necessary conditions for an optimal transceiver, Karush–Kuhn–Tucker (KKT) conditions, are satisfied in each iteration. Numerical results under the frequency-selective MIMO-OFDM channel, which is generated by the classical Zheng and Xiao's model, prove that the proposed transceiver can significantly reduce the feedback overhead without severe performance degradation.     

一种降低节点能量开销的ZigBee路由算法优化

为解决ZigBee网络由于不合理的路由策略导致节点能量浪费和网络陷入局部死亡的问题,提出一种降低节点能量开销的ZBR路由算法。所提ZBR优化算法在路由发送阶段,利用节点自动维护的邻居表信息,优先实现两跳路由传输;在路由发现过程中,根据最大传输跳数和节点间的父子关系,控制ZigBee网络中RN+节点RREQ分组的洪泛,减少能量浪费;在路由选择时,设计节点能量标志位和能量感知的路由成本函数,减少能量偏低节点的使用概率,降低网络开销和提高节点生存率。通过与原ZBR算法及其他几种改进ZBR算法进行剩余能量和节点生存率对比仿真实验,结果表明:改进的ZBR算法的平均剩余能量提高了7.74%,在网络运行80s时节点生存率提高了20.29%,也高于其他几种改进ZBR算法,该算法可有效减少网络能量消耗,大大提高节点生存率。