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PLAs in quantumdot cellular automata
 Proc. of Emerging VLSI Technologies and Architectures (ISVLSI’06
, 2006
"... Abstract — Various implementations of the Quantumdot Cellular Automata (QCA) device architecture may help many performance scaling trends continue as we approach the nanoscale. Experimental success has led to the evolution of a research track that looks at QCAbased design. The work presented in th ..."
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Abstract — Various implementations of the Quantumdot Cellular Automata (QCA) device architecture may help many performance scaling trends continue as we approach the nanoscale. Experimental success has led to the evolution of a research track that looks at QCAbased design. The work presented in this paper follows that track and looks at implementation friendly, programmable QCA circuits. Specifically, we present a novel, QCAbased, Programmable Logic Array (PLA) structure. Our PLA is capable of providing defect tolerance at both the device and architectural level, and limits the amount of determinism required in any fabrication process. The design is compact, exploits properties unique to QCA devices in order to ease programmability, and is relevant to all implementations of QCA. I.
Approximating the Maximum Sharing Problem
"... Abstract. In the maximum sharing problem (MS), we want to compute a set of (nonsimple) paths in an undirected bipartite graph covering as many nodes as possible of the first node layer of the graph, with the constraint that all paths have both endpoints in the second node layer and no node in that ..."
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Abstract. In the maximum sharing problem (MS), we want to compute a set of (nonsimple) paths in an undirected bipartite graph covering as many nodes as possible of the first node layer of the graph, with the constraint that all paths have both endpoints in the second node layer and no node in that layer is covered more than once. MS is equivalent to the nodeduplication based crossing elimination problem (NDCE) that arises in the design of molecular quantumdot cellular automata (QCA) circuits and the physical synthesis of BDD based regular circuit structures in VLSI design. We show that MS is NPhard, present a polynomialtime 1.5approximation algorithm, and show that MS cannot be approximated with a factor better than 740 unless P = NP. 739 1
On approximating the maximum simple sharing problem
 Proc. of the 17th International Symposium on Algorithms and Computation (ISAAC’06). Springer LNCS 4288
, 2006
"... Abstract. In the maximum simple sharing problem (MSS), we want to compute a set of nodedisjoint simple paths in an undirected bipartite graph covering as many nodes as possible of one layer of the graph, with the constraint that all paths have both endpoints in the other layer. This is a variation ..."
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Abstract. In the maximum simple sharing problem (MSS), we want to compute a set of nodedisjoint simple paths in an undirected bipartite graph covering as many nodes as possible of one layer of the graph, with the constraint that all paths have both endpoints in the other layer. This is a variation of the maximum sharing problem (MS) that finds important applications in the design of molecular quantumdot cellular automata (QCA) circuits and physical synthesis in VLSI. It also generalizes the maximum weight nodedisjoint path cover problem. We show that MSS is NPcomplete, present a polynomialtime 5approximation algorithm, 3 and show that it cannot be approximated with a factor better than 740 739 unless P = NP.
Modeling and Evaluating Errors due to Random Clock Shifts in Quantumdot Cellular Automata Circuits
"... This paper analyzes the effect of random phase shifts in the underlying clock signals on the operation of several basic Quantumdot Cellular Automata (QCA) building blocks. Such phase shifts can result from manufacturing variations or from uneven path lengths in the clocking network. We perform nume ..."
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This paper analyzes the effect of random phase shifts in the underlying clock signals on the operation of several basic Quantumdot 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 ipi2, 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 performance of all building blocks starts to drop once the phase shifts in the clocking network are characterized by a standard deviation, σ ≥ 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 Cout 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. Key Words: Quantumdot Cellular Automata (QCA), clocked QCA, emerging nanotechnologies, phase shift.
Using CAD to Shape Experiments in Molecular QCA
"... This paper examines how circuits and systems made from molecular QCA devices might function. Our design constraints are “chemically reasonable ” in that we consider the characteristics and dimensions of devices and scaffoldings (circuit boards to attach devices to) that have actually been fabricated ..."
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This paper examines how circuits and systems made from molecular QCA devices might function. Our design constraints are “chemically reasonable ” in that we consider the characteristics and dimensions of devices and scaffoldings (circuit boards to attach devices to) that have actually been fabricated (currently in isolation). We will show that not only is the work presented here a necessary first step for any work in QCA CAD, but also that by considering issues related to design can actually help shape experiments in the physical sciences for emerging, nanoscale devices. Our work shows that circuits, scaffoldings, substrates, and devices must all be considered simultaneously. Otherwise, there is a very real possibility that the devices and scaffoldings that are eventually manufactured will result in devices that only work in isolation. This work is especially timely as experimentalists are currently working to merge the different experimental tracks – i.e. to selectively place a QCA device. 1.
Nur A. ToubaAdder and Multiplier Design and Analysis
"... December 2006This dissertation is dedicated to my parents, ..."
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PLAs in Quantumdot Cellular Automata
"... Abstract — Research in the fields of physics, chemistry and electronics has demonstrated that Quantumdot Cellular Automata (QCA) is a viable alternative for nanoscale computing. However, little work on QCA has studied designing implementationfriendly programmable QCA circuits. This paper fills t ..."
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Abstract — Research in the fields of physics, chemistry and electronics has demonstrated that Quantumdot Cellular Automata (QCA) is a viable alternative for nanoscale computing. However, little work on QCA has studied designing implementationfriendly programmable QCA circuits. This paper fills this gap by presenting a novel QCAbased Programmable Logic Array (PLA) structure. In addition to being compact, the proposed PLA structure exploits some unique properties of QCA cells to achieve ease of implementation, programming and defect detection. These features are indispensable to the successful adoption of any nanoscale circuits. I.
Using CAD to Shape Experiments in Molecular QCA ABSTRACT
"... This paper examines how circuits and systems made from molecular QCA devices might function. Our design constraints are “chemically reasonable ” in that we consider the characteristics and dimensions of devices and scaffoldings (circuit boards to attach devices to) that have actually been fabricated ..."
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This paper examines how circuits and systems made from molecular QCA devices might function. Our design constraints are “chemically reasonable ” in that we consider the characteristics and dimensions of devices and scaffoldings (circuit boards to attach devices to) that have actually been fabricated (currently in isolation). We will show that not only is the work presented here a necessary first step for any work in QCA CAD, but also that by considering issues related to design can actually help shape experiments in the physical sciences for emerging, nanoscale devices. Our work shows that circuits, scaffoldings, substrates, and devices must all be considered simultaneously. Otherwise, there is a very real possibility that the devices and scaffoldings that are eventually manufactured will result in devices that only work in isolation. This work is especially timely as experimentalists are currently working to merge the different experimental tracks – i.e. to selectively place a QCA device. 1.
Dataflow in molecular QCA: Logic can “sprint”,
"... but the memory wall can still be a “hurdle”. ..."
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"... This Poster Presentation is brought to you for free and open access by the Office of Sponsored and Undergraduate Research at ValpoScholar. It has been accepted for inclusion in Celebration of Undergraduate Scholarship by an authorized administrator of ValpoScholar. For more information, please conta ..."
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This Poster Presentation is brought to you for free and open access by the Office of Sponsored and Undergraduate Research at ValpoScholar. It has been accepted for inclusion in Celebration of Undergraduate Scholarship by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at