Variability-Aware Design of Multilevel Logic Decoders for Nanoscale Crossbar Memories

The fabrication of crossbar memories with sublithographic features is expected to be feasible within several emerging technologies; in all of them, the nanowire (NW) decoder is a critical part since it bridges the sublithographic wires to the outer circuitry that is defined on the lithography scale. In this paper, we evaluate the addressing scheme of the decoder circuit for NW crossbar arrays, based on the existing technological solutions for threshold voltage differentiation of NW devices. This is equivalent to using a multivalued logic addressing scheme. With this approach, it is possible to reduce the decoder size and keep it defect tolerant. We formally define two types of multivalued codes (i.e., hot and reflexive codes), and we estimate their yield under high variability conditions. Multivalued hot decoders yield better area saving than n-ary reflexive codes, and under severe conditions, reflexive codes enable a nonvanishing part of the code space to randomly recover. The choice of the optimal combination of decoder type and logic level saves area up to 24%. We also show that the precision of the addressing voltages when a high variability affects the threshold voltages is a crucial parameter for the decoder design and permits large savings in memory area. Moreover, a precise knowledge about the variability level improves the design of memory decoders by giving the right optimal code

Design and Implementation 4-Bit Quaternary MVL Arithmetic and Logic Unit

In the recent years, there were major importance to Multiple Valued Logic (MVL), where the most common reasons for considering the implementation of MVL circuits better then binary valued circuits are that reducing wiring congestion as compared to binary circuits, using a single conductor to transmit three or more discrete voltage or current values allows for greater information content per wire and the circuit cost models would be more economical. Therefore, in this paper the MVL concepts have been used to design 4-bit quaternary MVL Arithmetic and Logic Unit, which is considered a basic unit of a MVL microprocessor. It is the "heart" of a microprocessor and we could say that everything else in the microprocessor is there to support the ALU. The proposed Arithmetic and Logic Unit will do the operations as Addition, Subtraction, Maximum, Minimum and Invert. Simulation Program with Integrated Circuit Emphasis (SPICE) tool in Cadence simulator used in simulation the proposed Arithmetic and Logic Unit. The simulation results tells that the design is more efficient compared with the binary ALU and the circuit will be less area and less number of transistors

NASA SERC 1990 Symposium on VLSI Design

This document contains papers presented at the first annual NASA Symposium on VLSI Design. NASA's involvement in this event demonstrates a need for research and development in high performance computing. High performance computing addresses problems faced by the scientific and industrial communities. High performance computing is needed in: (1) real-time manipulation of large data sets; (2) advanced systems control of spacecraft; (3) digital data transmission, error correction, and image compression; and (4) expert system control of spacecraft. Clearly, a valuable technology in meeting these needs is Very Large Scale Integration (VLSI). This conference addresses the following issues in VLSI design: (1) system architectures; (2) electronics; (3) algorithms; and (4) CAD tools

Enhancement of Exon Regions Recognition in Gene Sequences Using a Radix -4 Multi-valued Logic with DSP Approach

Numerous levels of concepts perform logical designand logical representations in an efficient manner. In typical and quantum theories of computation, Binary logic and Boolean algebra occupies an imperative place. But they havethe limitation of representing signals or sequences by using either binary ‘1’ or ‘0’. This has major drawbacks that the neutralities or any intermediate values are ignored which are essential in most of the applications. Because of the occurrence of such situations it is the need of the hour to look into other alternative logics in order to fulfill the necessities of the user in their respective applications. The binary logic can be replaced by Multi-Valued Logic (MVL), which grabs the positions of the major applications because of the ability to provide representation by using more than two values.As most of the significant applications are based on the logical sequences, the multi-valued logic shines because of its thriving feature. Genomic signal processing, a novel research area in bioinformatics,is one of the foremost applications which involve the operations of logical sequences. It is concerned with the digital signal representations and analysis of genomic data.Determination of the coding region in DNA sequence is one of the genomic operations.This leads to the identification of the characteristics of the gene which in turn finds out an individual’s behavior. In order to extract the coding regions on the basis of logical sequences a number of techniques have been proposed by researchers. But most of the works utilized binary logic, which lead to the problem of losing some of the coding regions and incorrectly recognizing non-coding regions as the coding regions. Hereby,we are proposing an approach for recognizing the exon regions from a gene sequence based on the multi-valued logic. In this approach, we have utilized fourlevel logical system, termed as quaternary logic for the representation of gene sequences and so that we recognize theexon regions from the DNA sequence

Multiple-Input Common-Gate FGUVMOS Transistor and Its Application in Multiple-Valued Logic Circuits

The demand for reduced area and power consumption have usually been met with improvements in processing techniques, allowing for increased integration and a reduction in the power supply voltage. Some technology improvements have also occurred, such as strained silicon and silicon-on-insulator. But some design techniques also feature a significant reduction in area and power consumption, such the asynchronous design approach. Reducing the amount of interconnects is another approach, for which multiple-valued logic might be an ideal candidate. This thesis explores the multiple-input common-gate FGUVMOS transistor and the design of multiple-valued logic circuits using this transistor. We examine in detail a UV-programming technique for initializing the floating-gate. There is no need for any extra programming circuitry with this programming method, since it utilizes the supply rail of the nMOS transistor to place a charge on the floating-gate. An important benefit of the floating-gate initialization is a matching of the pMOS and nMOS transistor at a predetermined current level. We also look closer at some of the layout issues concerning FGUVMOS circuits. We also explore a new area of application for the FGUVMOS transistor, namely multiple-valued logic. The main design parameter of the FGUVMOS transistor--the capacitive division ratios of the coupling capacitors to the floating-gate--is well suited for designing voltage-mode multiple-valued logic circuits. Several multiple-valued logic circuits are examined in detail and several design issues are addressed. Measurements on a fabricated chip are supplied, as well as simulations of the various circuits. And the voltage output functions for the presented circuits are also developed