1,173 research outputs found

    LOT: Logic Optimization with Testability - new transformations for logic synthesis

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    A new approach to optimize multilevel logic circuits is introduced. Given a multilevel circuit, the synthesis method optimizes its area while simultaneously enhancing its random pattern testability. The method is based on structural transformations at the gate level. New transformations involving EX-OR gates as well as Reed–Muller expansions have been introduced in the synthesis of multilevel circuits. This method is augmented with transformations that specifically enhance random-pattern testability while reducing the area. Testability enhancement is an integral part of our synthesis methodology. Experimental results show that the proposed methodology not only can achieve lower area than other similar tools, but that it achieves better testability compared to available testability enhancement tools such as tstfx. Specifically for ISCAS-85 benchmark circuits, it was observed that EX-OR gate-based transformations successfully contributed toward generating smaller circuits compared to other state-of-the-art logic optimization tools

    A Self-Repairing Execution Unit for Microprogrammed Processors

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    Describes a processor which dynamically reconfigures its internal microcode to execute each instruction using only fault-free blocks from the execution unit. Working without redundant or spare computational blocks, this self-repair approach permits a graceful performance degradatio

    Formation of Low Threshold Voltage Microlasers

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    Vertical cavity surface emitting lasers (VCSELs) with threshold voltages of 1.7V have been fabricated. The resistance-area product in these new vertical cavity lasers is comparable to that of edge-emitting lasers, and threshold currents as low as 3 mA have been measured. Molecular beam epitaxy was used to grow n-type mirrors, a quantum well active region, and a heavily Be-doped p-contact. After contact definition and alloying, passive high-reflectivity mirrors were deposited by reactive sputter deposition of SiO2/Si3N4 to complete the laser cavity

    Effects of Technology Mapping on Fault Detection Coverage in Reprogrammable FPGAs

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    Although Field-Programmable Gate Arrays (FPGAs) are tested by their manufacturers prior to shipment, they are still susceptible to failures in the field. In this paper, test vectors generated for the emulated (i.e., mission) circuit are fault simulated on two different models: the original view of the circuit, and the design as it is mapped to the FPGA\u27s logic cells. Faults in the cells and in the programming logic are considered. Experiments show that this commonly-used approach fails to detect most of the faults in the FPGA

    A Defect-tolerant Cluster in a Mesh SRAM-based FPGA

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    International audienceIn this paper, we propose the implementation of multiple defect-tolerant techniques on an SRAM-based FPGA. These techniques include redundancy at both the logic block and intra-cluster interconnect. In the logic block, redundancy is implemented at the multiplexer level. Its efficiency is analyzed by injecting a single defect at the output of a multiplexer, considering all possible locations and input combinations. While at the interconnect level, fine grain redundancy is introduced which not only bypasses defects but also increases routability. Taking advantage of the sparse intra-cluster interconnect structures, routability is further improved by efficient distribution of feedback paths allowing more flexibility in the connections among logic blocks. Emulation results show a significant improvement of about 15% and 34% in the robustness of logic block and intra-cluster interconnect respectively. Furthermore, the impact of these hardening schemes on the testability of the FPGA cluster for manufacturing defects is also investigated in terms of maximum achievable fault coverage and the respective cost

    Design and test of field programmable gate arrays in space applications

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    Field Programmable Gate Arrays (FPGAU's) offer substantial benefits in terms of flexibility and design integration. In addition to qualifying this device for space applications by establishing its reliability and evaluating its sensitivity to radiation, screening the programmed devices with Automatic Test Equipment (ATE) and functional burn-in presents an interesting challenge. This paper presents a review of the design, qualification, and screening cycle employed for FPGA designs in a space program, and demonstrates the need for close interaction between design and test engineers

    A writable programmable logic array

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    This thesis contains the analysis, design, and implementation of a writable programmable logic array integrated circuit. The WPLA is able to be reprogrammed any number of times as needed. A content addressable scheme is proposed to conduct READ, WRITE, and SEARCH operations in the WPLA. The WPLA is programmed by writing binary data into storage cells associated with each node in the AND/OR planes of the array; the binary data then form the personalities of the PLA. The layout of the WPLA will be implemented using Mentor Graphic\u27s CHIPGRAPH layout editor with 2 µm NMOS technology and MOSIS design rules. The event-driven logic level simulator QUICKSIM, and a MOS circuit level simulator MSIMON, are used to verify the functional and timing behavior of the WPLA
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