Efficient design of parity preserving logic in quantum-dot cellular automata targeting enhanced scalability in testing

Design of parity preserving logic based on emerging nanotechnology is very limited due to present technological limitation in tackling its high error rate. In this work, Quantum-dot cellular automata (QCA), a potential alternative to CMOS, is investigated for designing easily testable logic circuit. A novel self-testable logic structure referred to as the testable-QCA (t-QCA), using parity preserving logic, is proposed. Design flexibility of t-QCA then evaluated through synthesis of standard functions. The programmability feature of t-QCA is utilized to implement an ALU, realizing six important functions. Although the parity preservation property of t-QCA enables concurrent detection of permanent as well as the transient faults, an augmented test logic circuit (TC) using QCA primitives has been introduced to cover the cell defects in nanotechnology. Experimental results establish the efficiency of the proposed design that outperforms the existing technologies in terms of design cost and test overhead. The achievement of 100% stuck-at fault coverage and the 100% fault coverage for single missing/additional cell defects in QCA layout of the t-QCA gate, address the reliability issues of QCA nano-circuit design.     

Parallel pseudorandom number generation in GaAs cellular automata for high speed circuit testing

To facilitate test vector generation for high-speed circuits, we present the design and circuit simulation of parallel pseudorandom number generators in GaAs technology. These PRNGs are based on hybrid cellular automata (CA) in which mixtures of local rules are employed in one dimensional arrays, with minimal delay due to having only local wiring between neighboring cells. HSPICE simulations of these circuits demonstrate that they operate at a clock frequency above 1 GHz. Delay simulations indicate that GaAs PRNGs based upon linear feedback shift registers, in contrast with hybrid CAs, exhibit a degradation in clock frequency due to the effects of global interconnects, and that this degradation increases with the register length.This work was supported by Micronet, by the Canadian Microelectronics Corporation, and by the Natural Sciences and Engineering Research Council of Canada.     

On behavior of two-dimensional cellular automata with an exceptional rule under periodic boundary condition

This article deals with the behavior of two-dimensional(2-D) cellular automata(CA) with a special rule under periodic boundary condition by using matrix algebra.The important characteristics of CA have been studied,such as Garden of Eden(GOE),maximal transient length,maximal cycle length and so forth.Several necessary and sufficient conditions are provided,which guarantee a given configuration of being a GOE in different cases.Besides,algorithms are proposed to obtain the number of GOEs,the maximal transien...     

A structure and technique for pseudorandom-based testing of sequential circuits

Presented is a register structure and generator design which enables non-scan sequential testing using parallel pseudorandom-based patterns applied to the circuit's primary inputs. The proposed register structure and register control strategy uses the circuit under test's (CUT's) natural sequential activity to periodically alter a register's output bias to a value near 0.5 (i.e. alter the spread of 1's in the output stream). Thus, over time, it is possible to introduce a larger spread circuit states than that normally reachable when parallel pseudorandom-based test patterns are applied to the input lines of a CUT. Using the register modification, a simple hardware generation system can be designed and is suitable for both on-chip and external testing. Experiments indicate that high fault coverage is attainable in a relatively short test time.     

Quantitative analysis for linear hybrid cellular automata and LFSR as built-in self-test generators for sequential faults

This paper presents a combinatorial method of evaluating the effectiveness of linear hybrid cellular automata (LHCA) and linear feedback shift registers (LFSR) as generators for stimulating faults requiring a pair of vectors. We provide a theoretical analysis and empirical comparisons to see why the LHCA are better than the LFSRs as generators for sequential-type faults in a built-in self-test environment. Based on the concept of a partner set, the method derives the number of distinctk-cell substate vectors which have 2^2k , 1k[n/2], transition capability for ann-cell LHCA and ann-cell LFSR with maximum length cycles. Simulation studies of the ISCAS85 benchmark circuits provide evidence of the effectiveness of the theoretrical metric.This work was supported in part by Reserach Grants No. 5711 and No. 39409 and a Strategic Grant from the Natural Sciences and Engineering Research Council of Canada and by an equipments loan from the Canadian Microelectronics Corporation.A preliminary version of this paper is partially presented at theIEEE ISCAS'94, May 1994.     

A novel FPGA-programmable switch matrix interconnection element in quantum-dot cellular automata

The Quantum-dot cellular automata (QCA) is a novel nanotechnology, promising extra low-power, extremely dense and very high-speed structure for the construction of logical circuits at a nanoscale. In this paper, initially previous works on QCA-based FPGA’s routing elements are investigated, and then an efficient, symmetric and reliable QCA programmable switch matrix (PSM) interconnection element is introduced. This element has a simple structure and offers a complete routing capability. It is implemented using a bottom-up design approach that starts from a dense and high-speed 2:1 multiplexer and utilise it to build the target PSM interconnection element. In this study, simulations of the proposed circuits are carried out using QCAdesigner, a layout and simulation tool for QCA circuits. The results demonstrate high efficiency of the proposed designs in QCA-based FPGA routing.     

An efficient design of CORDIC in Quantum-dot cellular automata technology

Power dissipation of future-integrated systems, consisting of a numberless of devices, is a challenge that cannot be easily solved by classical technologies. Quantum-dot Cellular Automata (QCA) is a Field-Coupled Nanotechnology (FCN) and a potential alternative to traditional CMOS technologies. It offers various features like extremely low-power dissipation, very high operating frequency and nanoscale feature size. This study presents a novel design of CORDIC circuit based on QCA technology. The proposed circuit is based on several proposed QCA sub-modules as adder and Flip-Flop. To design and verify the proposed architecture, QCADesigner tool is employed and power consumption is estimated using QCAPro software. The proposed QCA CORDIC achieves about 69% reduction in power and area compared to previous existing designs. The outcome of this work can open up a new window of opportunity for the design of the CORDIC module and can be used in low-power signal and image processing systems.     

Design and evaluation of new majority gate-based RAM cell in quantum-dot cellular automata

Quantum-dot cellular automata is one of the candidate technologies used in Nano scale computer design and a promising replacement for conventional CMOS circuits in the near future. Since memory is one of the significant components of any digital system, designing a high speed and well-optimized QCA random access memory (RAM) is a remarkable subject. In this paper, a new robust five-input majority gate is first presented, which is appropriate for implementation of simple and efficient QCA circuits in single layer. By employing this structure, a novel RAM cell architecture with set and reset ability is proposed. This architecture has a simple and robust structure that helps achieving minimal area, as well as reduction in hardware requirements and clocking zone numbers. Functional correctness of the presented structures is proved by using QCADesigner tool. Simulation results confirm efficiency and usefulness of the proposed architectures vis-à-vis state-of-the-art.     

Design and simulation of sequential circuits in quantum-dot cellular automata: Falling edge-triggered flip-flop and counter study

Quantum-dot Cellular Automata (QCA) is an emerging nanotechnology, with extremely small feature size and ultralow power consumption comparing with transistor-based technology. Anteriority, basic level-triggered flip-flop designs based on QCA implementation were examined. In this paper, we utilize the unique QCA characteristics and clock zones to design falling edge-triggered J-K flip-flop that is stable and practical. Simulation with the QCADesigner simulator is performed to verify the functionality of the proposed falling edge-triggered flip-flop. This paper also explores the design of counters. Synchronous counters are designed with several different bit sizes and simulation results demonstrate the validity of them.     

A novel nonnegative decomposition method and its application to 2-D digital filter design

In designing two-dimensional (2-D) digital filters in the frequency domain, an efficient technique is to first decompose the given 2-D frequency domain design specifications into one-dimensional (1-D) ones, and then approximate the resulting 1-D magnitude specifications using the well-developed 1-D filter design techniques. Finally, by interconnecting the designed 1-D filters one can obtain a 2-D digital filter. However, since the magnitude responses of digital filters must be nonnegative, it is required that the decomposition of 2-D magnitude specifications result in nonnegative 1-D magnitude specifications. We call such a decomposition the nonnegative decomposition. This paper proposes a nonnegative decomposition method for decomposing the given 2-D magnitude specifications into 1-D ones, and then transforms the problem of designing a 2-D digital filter into that of designing 1-D filters. Consequently, the original problem of designing a 2-D filter is significantly simplified.     

Modeling and Evaluating Errors Due to Random Clock Shifts in Quantum-Dot Cellular Automata Circuits

This paper analyzes the effect of random phase shifts in the underlying clock signals on the operation of several basic Quantum-dot Cellular Automata (QCA) building blocks. Such phase shifts can result from manufacturing variations or from uneven path lengths in the clocking network. We perform numerical simulations of basic building blocks using two different simulation engines available in the QCADesigner tool. We assume that the phase shifts are characterized by a Gaussian distribution with a mean value of , where i is the clock number and a standard deviation, σ, which is varied in each simulation. Our results indicate that the sensitivity of building blocks to phase shifts depends primarily on the layout while the reliability of all building blocks starts to drop once the standard deviation, σ exceeds 4°. A full adder was simulated to analyze the operation of a circuit featuring a combination of the building blocks considered here. Results are consistent with expectations and demonstrate that the carry output of the full adder is better able to withstand the phase shifts in the clocking network than the Sum output which features a larger combination of the simulated building blocks.

可调谐滤波器在DWDM系统中的应用

可调谐滤波器是实现未来全光网络的重要器件,在DWDM系统中有着广泛应用.文章介绍了几种常用的可调谐滤波器的原理、最新研究及其在可重构光分插复用和光传输性能监测中的应用.     

基于量子元胞自动机的PLA故障分析和检测

量子元胞自动机(quantum-dot cellular automata,QCA)可编程逻辑阵列(programma-ble logic array,PLA)结构可用于实现大规模可编程逻辑电路。分析了4种故障类型发生在PLA单元的8个区域中的影响,得出了具体的影响效果。其中,直接或间接致使隐含线和与门发生逻辑错误的故障均会导致PLA中故障所在行整行失效,其他故障只会影响故障所在的PLA单元的逻辑功能和配置,而对PLA中的其他单元没有影响。此外,基于故障分析,提出了具体的PLA故障检测方法。     

量子元胞自动机器件和电路的研究进展

量子元胞自动机(QCA)是一种新颖的纳米技术,该技术不再通过电流或电压而是基于场相互作用进行信息的计算和传递。首先,综述了两种量子元胞自动机(EQCA和MQCA)器件的计算原理、基本逻辑门和时钟。指出了QCA元胞构成的不同线结构可在相同层交叉传递信号而不受影响。然后,进一步总结了制备QCA器件和功能阵列或电路的实验方法和材料,得出MQCA器件和分子EQCA器件的发展将使该器件逐步达到实际应用水平的结论。详细讨论了目前QCA器件和电路(尤其是存储单元结构)研究取得的重要进展以及面临的问题。提出了QCA器件未来理论和应用研究中的开放课题和方向。     

QCA电路的缺陷研究

针对量子元胞自动机电路中出现的元胞移位等元胞缺陷,介绍了基于QCADesigner的元胞缺陷分析,得出了特定结构的容错范围。对于制造过程出现的单电子故障,分析了不同输入时单电子故障对传输线和反相器的影响。对于制造过程中出现的漂移电荷缺陷,分析了这些缺陷对传输线的影响。通过改变元胞与传输线之间的距离,研究了QCA传输线之间的串扰问题,得出了其容错范围。最后对RS触发器中出现的元胞缺陷采用测试序列进行了分析研究,从而为进一步研究QCA电路的缺陷提供了依据和方向。     

Analysis of TiO2 for microelectronic applications: effect of deposition methods on their electrical properties

Metal oxide semiconductor (MOS) device down-scaling is a powerful driving force for the evolution of microelectronics.The downsizing rate of metal oxide semiconductor field effect transistors (MOSFETs)...     

Origin of Mobile Cellular Network Technologies and Markets in Germany and China

The inventive foundation of mobile cellular technologies was laid about 100 years ago. Wireless voice service was commercialised in the 1940s by AT&T. In Germany, public and non-cellular wireless service was established by Deutsche Bundespost in the late 1950s and the first analogue cellular network called C-Netz emerged in the mid-1980s. In China, the first mobile cellular networks called TACS-A and TACS-B were installed by Ministry of Post and Telecommunication in the late 1980s. While describing the events in Germany and China, this paper concentrates on discussing the related technologies and their impacts in the marketplace. A comparison summarises some important findings. Japan and Europe's Nordic countries were the first nations to commercialise the 1st generation analogous cellular technologies. There existed A- and B-Network in Germany and China, but the network nature of them is quite different. The market development in Germany and China was similar. The enlarged network capacity accommodated gradually more subscribers and prices related to the cellular services fell continuously. However, China's fee system was more complicated and has adopted the RPP regime, while Germany has been using the CPP billing. The article concludes that implications such as the relationship between science and technology, time lag between scientific discovery and technological applications and technology spillover from military to civilian area are the economic lessons learnt from the story of cellular origin.     

激光照射,免疫抑制剂及其配合对免疫细胞的影响

应用３９．７２Ｊ／ｃｍ＾２的Ｈｅ－Ｎｅ激光连续１４天照射健康大鼠脊背正中线皮肤，并同时分别与亚剂量的免疫抑制剂环孢霉素Ａ，硫唑嘌呤相匹配，观察了它们对Ｔ，Ｂ淋巴细胞数，淋巴细胞转化刺激指数（Ｓ，Ｉ），１０＾６个淋巴细胞ＣＰＭ数的影响，结果表明，大剂量Ｈｅ－Ｎｅ激光和Ａｚ唑嘌呤均可降低大鼠Ｂ淋巴细胞数，大剂量Ｈｅ－Ｎｅ激光，环孢霉素Ａ，硫唑嘌呤及激光照射与二者配合，均可使淋巴细胞转化刺激指数（Ｓ，Ｉ     

Imaging one-dimensional and two-dimensional planar photodiode detectors fabricated by ion milling molecular beam epitaxy CdHgTe

Imaging one-dimensional (1-D) and two-dimensional (2-D) arrays of mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) planar photodiodes were fabricated by ion milling of vacancy-doped molecular beam epitaxy Cd_xHg_1−xTe layers. Sixty-four-element 1-D arrays of 26×26 μm² or 26×56 μm² diodes were processed. Zero-bias resistance-area values (R₀A) at 77 K of 4×10⁶ Θcm² at cutoff wavelength λ_CO=4.5 μm were measured, as well as high quantum efficiencies. To avoid creating a leakage current during ball bonding to the 1-D array diodes, a ZnS layer was deposited on top of the CdTe passivation layer, as well as extra electroplated Au on the bonding pads. The best measured noise equivalent temperature difference (NETD) on a LWIR array was 8 mK, with a median of 14 mK for the 42 operable diodes. The best measured NETD on a MWIR array was 18 mK. Two-D arrays showed reasonably good uniformity of R₀A and zero-bias current (I₀) values. The first 64×64 element 2-D array of 16×16 μm² MWIR diodes has been hybridized to read-out electronics and gave median NETD of 60 mK.