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This article proposes a methodology for critical path selection and delay sensor insertion for aging monitoring in field-programmable gate arrays (FPGAs). The aging information can be used to reconfigure FPGAs to achieve better performance or wear leveling. To filter out the paths aging less aggressively, our methodology decides based on both physical-level parameters [e.g., path delay, process variation, temperature, static stress (duty cycle), and dynamic stress (switching activity) as well as aging-relevant parameters (e.g., fan-out, and endpoint physical location)]. After selection of an optimal set of paths, age sensors, introduced in our earlier work, are placed in a distributed fashion throughout the FPGA area to provide aging information of its various parts as they are being used. Accurate aging models for FPGAs are required to determine the contribution of the above-mentioned parameters in aging. In this article, ASICs’ aging models are adapted for FPGAs through measurement-based fitting approach. The experimental results using various benchmarks reveal that our algorithm selects paths with a minimum error. [ABSTRACT FROM AUTHOR]

A promising solution to reliability challenges in nano-scale fabrication technologies is self-test and reconfiguration. In this direction, we propose an autonomous test mechanism for online detection of permanent faults in many-core processors. Several hardware test components are incorporated in the many-core architecture. Some of these components distribute software-based self-test routines among the processing cores and make each test routine accessible for a limited amount of time. A processing core that has an idle slot executes the test routine, otherwise it skips it without loss of test continuity. Several components of the proposed test architecture monitor behavior of the processing cores during execution of test routines, detect faulty cores, and make their omission from the system possible. We propose the use of an extended form of Petri NET modeling method to model and analyze the proposed test mechanism and tune our test architecture to preserve quality of test, and at the same time, manage the overall test time. Our experimental results show that test time and hardware overhead of the proposed test mechanism are low and its performance overhead is zero. Furthermore, the proposed test architecture can efficiently scale to a many-core with a large number of processing cores. [ABSTRACT FROM AUTHOR]

This article proposes an efficient and accurate embedded motor imagery-based brain–computer interface (MI-BCI) that meets the requirements for wearable and real-time applications. To achieve a suitable accuracy considering hardware constraints, we explore BCI transducer algorithms, among which Infinite impulse response (IIR) filter, common spatial pattern, and support vector machine are used to preprocess, extract features, and classify data, respectively. With our hardware implementation of these tasks, we have achieved an accuracy of 77%. Our system is designed at register transfer level (RTL) targeting an ASIC implementation, which significantly decreases power consumption, latency, and area compared to the state-of-the-art (SoA) architectures for embedded BCI systems. To this end, we fold IIR filters using time-shared and RAM-based techniques and use hardware-friendly algorithms for the implementation of other tasks. The RTL design is realized on 45 nm CMOS technology consuming 4 mW power and 0.25 mm2 area, which outperforms the SoA platforms for embedded BCI systems. To further illustrate the outperformance of our design, the proposed architecture is implemented on Virtex-7 field program gate array as a prototyping platform consuming 6 μJ energy with 1.52% area utilization. [ABSTRACT FROM AUTHOR]

In this article, we propose a fine-grained FPGA aging mitigation method. Our method focuses on Look Up Tables (LUTs) on which Boolean functions are mapped. Based on our observations, for any configuration, even if it is carefully selected, a number of LUT transistors experience severe stress rates. Therefore, an algorithm is presented to select several alternative configurations for each LUT. Alternative configurations are obtained by LUT input reordering. These alternative configurations are rotationally loaded into the FPGA. Experimental results shows that our method achieves 263 and 14.1 percent Mean Time To Failure (MTTF) improvement for Hot Carrier Injection (HCI) and Bias Temperature Instability (BTI), respectively. Additionally, due to changing only local routings, our method imposes up to 1 percent performance overhead to the systems. [ABSTRACT FROM AUTHOR]

This paper proposes a highly scalable sensor design for late transition detection in FPGA based platforms. Transition delays occur because of aging mechanisms such as Biased Temperature Instability (BTI) and Hot Carrier Injection (HCI). We propose a sensor clock (SCLK) that is a function of minimum slack time of a set of paths selected for age monitoring. There will be one such clock for many sensors as are needed in an entire FPGA. Our proposed sensor architecture makes it possible for a single SCLK to be shared by all sensors. Additionally, the proposed sensor occupies one slice (basic FPGA logic block), which leads to low area, power, and performance overhead. Using Artix-7-based board, experimental results demonstrate that the proposed aging sensor detects aging earlier than existing sensors and provides less power and performance overheads. [ABSTRACT FROM AUTHOR]

In this paper, a 7T SRAM cell with differential write and single ended read operations working in the near-threshold region is proposed. The structure is based on modifying a recently proposed 5T cell which uses high and low V TH transistors to improve the read and write stability. To enhance the read static noise margin (RSNM) while keeping the high write margin and low write time, an extra access transistor is used and the threshold voltages of the SRAM transistors are appropriately set. In addition, to maintain the low leakage power of the cell and increase the I on / I off ratio of its access transistors, a high V TH transistor is used in the pull down path of the cell. To assess the efficacy of the proposed cell, its characteristics are compared with those of 5T, 6T, 8T, and 9T SRAM cells. The characteristics are obtained from HSPICE simulations using 20 nm, 16 nm, 14 nm, 10 nm, and 7 nm FinFET technologies assuming a supply voltage of 500 mV. The results reveal high write and read margins, the highest I on / I off ratio, a fast write, and ultra-low leakage power in the hold “0” state for the cell. Therefore, the suggested 7T cell may be considered as one of the better design choices for both high performance and low power applications. Also, the changes of cell parameters when the temperature rises from −40 °C to 100 °C are investigated. Finally, the write margin as well as the read and hold SNMs of the cell in the presence of the process variations are studied at two supply voltages of 400 mV and 500 mV. The study shows that the proposed cell meets the required cell sigma value (6 σ ) under all conditions. [ABSTRACT FROM AUTHOR]

This paper concentrates on high-level data-flow optimization and synthesis techniques for datapath intensive designs such as those in Digital Signal Processing (DSP), computer graphics and embedded systems applications, which are modeled as polynomial computations over Z2^{n_1 } \times Z2^{n_2 } \times \cdots \times Z2^{n_d } to Z2^m . Our main contribution in this paper is proposing an optimization method based on functional decomposition of multivariate polynomial in the form of f(x) = g(x) \;o \;h(x) + f0 = g(h(x)) + f0 to obtain good building blocks, and vanishing polynomials over Z2^m to add/delete redundancy to/from given polynomial functions to extract further common sub-expressions. Experimental results for combinational implementation of the designs have shown an average saving of 38.85 and 18.85 percent in the number of gates and critical path delay, respectively, compared with the state-of-the-art techniques. Regarding the comparison with our previous works, the area and delay are improved by 10.87 and 11.22 percent, respectively. Furthermore, experimental results of sequential implementations have shown an average saving of 39.26 and 34.70 percent in the area and the latency, respectively, compared with the state-of-the-art techniques. [ABSTRACT FROM PUBLISHER]