19,652 research outputs found
Majority Logic Synthesis for Spin Wave Technology
Spin Wave Devices (SWDs) are promising beyond-CMOS candidates. Unlike traditional charge-based technologies, SWDs use spin as information carrier that propagates in waves. In this scenario, the logic primitive for computation is the majority gate. The majority gate has a greater expressive power than standard NAND/NOR gates, allowing SWD circuits to be more compact than CMOS, already at the logic level. Also, because there is not charge carrier transport, SWDs are estimated to have ultra-low power consumption. However, in order to exploit this opportunity, a native majority synthesis methodology is needed to fit the SWD technology needs. In this paper, we employ Majority-Inverter Graphs (MIGs) to naturally represent and synthesize SWD circuits. Thanks to the correspondence between the functionality of SWD primitive gates and MIG elements, MIG optimization intrinsically aims at minimum cost SWD implementations. Experimental results over MCNC benchmarks validate the efficiency of MIGs in SWD synthesis. As compared to traditional AND-Inverter Graph (AIG) synthesis, MIGs generate, on average, SWD circuits with 1.30Ă— smaller area-delay-power product (ADP), improving their delay performance by 18%
A Sound and Complete Axiomatization of Majority-n Logic
Manipulating logic functions via majority operators recently drew the
attention of researchers in computer science. For example, circuit optimization
based on majority operators enables superior results as compared to traditional
logic systems. Also, the Boolean satisfiability problem finds new solving
approaches when described in terms of majority decisions. To support computer
logic applications based on majority a sound and complete set of axioms is
required. Most of the recent advances in majority logic deal only with ternary
majority (MAJ- 3) operators because the axiomatization with solely MAJ-3 and
complementation operators is well understood. However, it is of interest
extending such axiomatization to n-ary majority operators (MAJ-n) from both the
theoretical and practical perspective. In this work, we address this issue by
introducing a sound and complete axiomatization of MAJ-n logic. Our
axiomatization naturally includes existing majority logic systems. Based on
this general set of axioms, computer applications can now fully exploit the
expressive power of majority logic.Comment: Accepted by the IEEE Transactions on Computer
Mathematical Estimation of Logical Masking Capability of Majority/Minority Gates Used in Nanoelectronic Circuits
In nanoelectronic circuit synthesis, the majority gate and the inverter form
the basic combinational logic primitives. This paper deduces the mathematical
formulae to estimate the logical masking capability of majority gates, which
are used extensively in nanoelectronic digital circuit synthesis. The
mathematical formulae derived to evaluate the logical masking capability of
majority gates holds well for minority gates, and a comparison with the logical
masking capability of conventional gates such as NOT, AND/NAND, OR/NOR, and
XOR/XNOR is provided. It is inferred from this research work that the logical
masking capability of majority/minority gates is similar to that of XOR/XNOR
gates, and with an increase of fan-in the logical masking capability of
majority/minority gates also increases
Non-volatile spin wave majority gate at the nanoscale
A spin wave majority fork-like structure with feature size of 40\,nm, is
presented and investigated, through micromagnetic simulations. The structure
consists of three merging out-of-plane magnetization spin wave buses and four
magneto-electric cells serving as three inputs and an output. The information
of the logic signals is encoded in the phase of the transmitted spin waves and
subsequently stored as direction of magnetization of the magneto-electric cells
upon detection. The minimum dimensions of the structure that produce an
operational majority gate are identified. For all input combinations, the
detection scheme employed manages to capture the majority phase result of the
spin wave interference and ignore all reflection effects induced by the
geometry of the structure
Inversion optimization in majority-inverter graphs
Many emerging nanotechnologies realize majority gates as primitive building blocks and they benefit from a majority-based synthesis. Recently, Majority-Inverter Graphs (MIGs) have been introduced to abstract these new technologies. We present optimization techniques for MIGs that aim at rewriting the complemented edges of the graph without changing its shape. We demonstrate the performance of our optimization techniques by considering three cases of emerging technology design: semi-custom digital design using Spin Wave Devices (SWDs) and Quantum-Dot Cellular Automata (QCA); and logic in-memory operation within Resistive Random Access Memories (RRAMs). Our experimental results show that SWD and QCA technologies benefit from complemented edges minimization. Area, delay, and power of SWD-based circuits are improved by 13.8%, 21.1%, and 9.2% respectively, while the number of QCA cells in QCA-based circuits can be decreased by 4.9% on average. Reductions of 14.4% and 12.4% in the number of devices and sequential steps respectively can be achieved for RRAMs when the number of nodes with exactly one complemented input is increased during MIG optimization
Elastic transport through dangling-bond silicon wires on H passivated Si(100)
We evaluate the electron transmission through a dangling-bond wire on
Si(100)-H (2x1). Finite wires are modelled by decoupling semi-infinite Si
electrodes from the dangling-bond wire with passivating H atoms. The
calculations are performed using density functional theory in a non-periodic
geometry along the conduction direction. We also use Wannier functions to
analyze our results and to build an effective tight-binding Hamiltonian that
gives us enhanced insight in the electron scattering processes. We evaluate the
transmission to the different solutions that are possible for the dangling-bond
wires: Jahn-Teller distorted ones, as well as antiferromagnetic and
ferromagnetic ones. The discretization of the electronic structure of the wires
due to their finite size leads to interesting transmission properties that are
fingerprints of the wire nature
Towards Logic Functions as the Device using Spin Wave Functions Nanofabric
As CMOS technology scaling is fast approaching its fundamental limits, several new nano-electronic devices have been proposed as possible alternatives to MOSFETs. Research on emerging devices mainly focusses on improving the intrinsic characteristics of these single devices keeping the overall integration approach fairly conventional. However, due to high logic complexity and wiring requirements, the overall system-level power, performance and area do not scale proportional to that of individual devices.
Thereby, we propose a fundamental shift in mindset, to make the devices themselves more functional than simple switches. Our goal in this thesis is to develop a new nanoscale fabric paradigm that enables realization of arbitrary logic functions (with high fan-in/fan-out) more efficiently. We leverage on non-equilibrium spin wave physical phenomenon and wave interference to realize these elementary functions called Spin Wave Functions (SPWFs).
In the proposed fabric, computation is based on the principle of wave superposition. Information is encoded both in the phase and amplitude of spin waves; thereby providing an opportunity for compressed data representation. Moreover, spin wave propagation does not involve any physical movement of charge particles. This provides a fundamental advantage over conventional charge based electronics and opens new horizons for novel nano-scale architectures.
We show several variants of the SPWFs based on topology, signal weights, control inputs and wave frequencies. SPWF based designs of arithmetic circuits like adders and parallel counters are presented. Our efforts towards developing new architectures using SPWFs places strong emphasis on integrated fabric-circuit exploration methodology. With different topologies and circuit styles we have explored how capabilities at individual fabric components level can affect design and vice versa. Our estimates on benefits vs. 45nm CMOS implementation show that, for a 1-bit adder, up to 40x reduction in area and 228x reduction in power is possible. For the 2-bit adder, results show that up to 33x area reduction and 222x reduction in power may be possible.
Building large scale SPWF-based systems, requires mechanisms for synchronization and data streaming. In this thesis, we present data streaming approaches based on Asynchronous SPWFs (A-SPWFs). As an example, a 32-bit Carry Completion Sensing Adder (CCSA) is shown based on the A-SPWF approach with preliminary power, performance and area evaluations
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