A pipelined architecture is proposed in this work to speed up the point multiplication in elliptic curve cryptography (ECC). This is achieved, at first; by pipelining the arithmetic unit to reduce the critical path delay. Second, by reducing the number of clock cycles (latency), which is achieved through careful scheduling of computations involved in point addition and point doubling. These two factors thus, help in reducing the time for one point multiplication computation. On the other hand, the small area overhead for this design gives a higher throughput/area ratio. Consequently, the proposed architecture is synthesised on different FPGAs to compare with the state-of-the-art. The synthesis results over GF(2 ^m ) show that the proposed design can work up to a frequency of 369, 357 and 337 MHz when implemented for m = 163, 233 and 283 bit key lengths, respectively, on Virtex-7 FPGA. The corresponding throughput/slice figures are 42.22, 12.37 and 9.45, which outperform existing implementations.

A comprehensive test set targets the detection of several fault models. As an example, in this study, stuck-at faults, transition faults and four-way bridging faults are targeted. Bridging faults represent a fault model where it is necessary to select a subset of target faults from all the possible faults. After test generation for single stuck-at faults, undetectable single stuck-at faults can be used for identifying undetectable transition and four-way bridging faults. These faults can be removed from the sets of target faults to reduce the test generation effort. The new contribution of the study is related to the possibility of updating the set of target bridging faults again after test generation for transition faults. The analysis performed in the study leads to the premise that the presence of an undetectable or aborted transition fault on a line g makes bridging faults that are associated with line g less likely to be detected. As a result, line g may be covered by fewer bridging faults than selected for it, creating a test hole. To address this issue, the study suggests that more bridging faults should be selected for line g in this case. Experimental results are presented to support the discussion.

Multicore processors are widely used in today's real-time embedded systems to satisfy the performance and predictability requirements as well as reduce cost. A vast majority of multicore embedded systems are running several tasks with mixed-criticality, in which the non-functional requirements of the tasks are different or even conflicting. A major challenge in mixed-criticality systems is to maximise the efficiency of shared resources while satisfying the criticality requirements. Shared memory is a key component that should be well managed and memory controller plays the main role in this case. Several memory controllers have been introduced in the literature for multicore processors. In this article, the authors performed a deep investigation on three state-of-the-art memory controllers using gem5 full-system simulator and Xilinx ISE Design Suite, and compared them in terms of predictability and performance. Then, the authors proposed a memory controller that provides the same predictability as the most predictable existing controller while improving the performance by 12.3%.

The interconnect between the cores of System-on-Chip (SOC) degrades the circuit performance by contributing to circuit delay and power consumption. To reduce this problem, SOC-based three-dimensional (3D) integrated circuit (IC) technology as a promising solution where multiple layers are stacked together decreasing the length of interconnect. However, 3D IC invites some new problems including more complexity in test generation. Testing of 3D IC requires test access architecture called Test Access Mechanism (TAM) for the purpose of transport of test stimuli to the cores placed in different layers. During testing due to increasing switching activity, any circuit demands higher power consumption and it becomes more acute for 3D IC. Moreover, testing of 3D ICs has other constraints. In this study, the authors address the issue of 3D IC testing using genetic algorithm-based approach to decrease test time. At first, available TAM width is partitioned into some fixed groups and they have to find partitioning of TAM and distribution of cores among layers with a goal to decrease test time. Next, they do the same considering, variable partitions with or without certain power limits. Experimental results establish the efficacy of the authors’ method.

In this study, reduced precision operations are investigated in order to improve the speed and energy efficiency of SNN implementation. Instead of using the 32-bit single-precision floating-point format, small floating-point format and fixed-point format are used to represent SNN parameters and to perform SNN operations. The analyses are performed on the training and inference of a leaky integrate-and-fire model-based SNN that is trained and used to classify the handwritten digits in MNIST database. The analysis results show that for SNN inference, the floating-point format with 4-bit exponent and 3-bit mantissa or the fixed-point format with 6-bit integer and 7-bit fraction can be used without any accuracy degradation. For training, a floating-point format with 5-bit exponent and 3-bit mantissa or a fixed-point format with 6-bit integer and 10-bit fraction can be used to obtain full accuracy. The proposed reduced precision formats can be used in SNN hardware accelerator design and the selection between floating-point and fixed-point can be determined by design requirements. A case study of SNN implementation on field-programmable gate array device is performed. With reduced precision numerical formats, memory footprint, computing speed, and resource utilisation are improved. As a result, the energy efficiency of SNN implementation is also improved.

Thermal issues are rapidly evolving in the field-programmable gate arrays (FPGAs) and are being intensely studied as these issues appear to significantly affect the delay performance of FGPAs. A ring oscillator has been widely used as a digital temperature sensor to sense this thermal effect on FPGAs. The delay generated by the ring oscillator will vary depending on the temperature environment due to negative bias temperature instability, hot carrier injection and electromigration. It is therefore critical to adopt an accurate ring oscillator design to effectively measure the delay in FGPAs. In this study, a digital temperature sensor with a stable ring oscillator is proposed. Measurement periods of 512 and 4096 clock cycles have been implemented and the relationship between temperature, delay and total count has been established. The results show that as the temperature increases to 100°C, the delay decreases by 3.99 and 33.98% for 512 and 4096 clock cycles, respectively. It has been found that in order to reduce the degradation effect on the Virtex-6 FPGA, adopting a measurement period of 512 clock cycles is the best method. The measured data is successfully validated through a set of simulations. Thus, it may benefit a system designer and industrial player, especially in designing temperature-based FPGAs.