TFI-FTS: An efficient transient fault injection and fault-tolerant system for asynchronous circuits on FPGA platform

Designing VLSI digital circuits is challenging tasks because of testing the circuits concerning design time. The reliability and productivity of digital integrated circuits are primarily affected by the defects in the manufacturing process or systems. If the defects are more in the systems, which leads the fault in the systems. The fault tolerant systems are necessary to overcome the faults in the VLSI digital circuits. In this research article, an asynchronous circuits based an effective transient fault injection (TFI) and fault tolerant system (FTS) are modelled. The TFI system generates the faults based on BMA based LFSR with faulty logic insertion and one hot encoded register. The BMA based LFSR reduces the hardware complexity with less power consumption on-chip than standard LFSR method. The FTS uses triple mode redundancy (TMR) based majority voter logic (MVL) to tolerant the faults for asynchronous circuits. The benchmarked 74X-series circuits are considered as an asynchronous circuit for TMR logic. The TFI-FTS module is modeled using Verilog-HDL on Xilinx-ISE and synthesized on hardware platform. The Performance parameters are tabulated for TFI-FTS based asynchronous circuits. The performance of TFI-FTS Module is analyzed with 100% fault coverage. The fault coverage is validated using functional simulation of each asynchronous circuit with fault injection in TFI-FTS Module

Delay Measurements and Self Characterisation on FPGAs

This thesis examines new timing measurement methods for self delay characterisation of Field-Programmable Gate Arrays (FPGAs) components and delay measurement of complex circuits on FPGAs. Two novel measurement techniques based on analysis of a circuit's output failure rate and transition probability is proposed for accurate, precise and efficient measurement of propagation delays. The transition probability based method is especially attractive, since it requires no modifications in the circuit-under-test and requires little hardware resources, making it an ideal method for physical delay analysis of FPGA circuits. The relentless advancements in process technology has led to smaller and denser transistors in integrated circuits. While FPGA users benefit from this in terms of increased hardware resources for more complex designs, the actual productivity with FPGA in terms of timing performance (operating frequency, latency and throughput) has lagged behind the potential improvements from the improved technology due to delay variability in FPGA components and the inaccuracy of timing models used in FPGA timing analysis. The ability to measure delay of any arbitrary circuit on FPGA offers many opportunities for on-chip characterisation and physical timing analysis, allowing delay variability to be accurately tracked and variation-aware optimisations to be developed, reducing the productivity gap observed in today's FPGA designs. The measurement techniques are developed into complete self measurement and characterisation platforms in this thesis, demonstrating their practical uses in actual FPGA hardware for cross-chip delay characterisation and accurate delay measurement of both complex combinatorial and sequential circuits, further reinforcing their positions in solving the delay variability problem in FPGAs

The Fifth NASA Symposium on VLSI Design

The fifth annual NASA Symposium on VLSI Design had 13 sessions including Radiation Effects, Architectures, Mixed Signal, Design Techniques, Fault Testing, Synthesis, Signal Processing, and other Featured Presentations. The symposium provides insights into developments in VLSI and digital systems which can be used to increase data systems performance. The presentations share insights into next generation advances that will serve as a basis for future VLSI design

Fault-tolerant computer study

A set of building block circuits is described which can be used with commercially available microprocessors and memories to implement fault tolerant distributed computer systems. Each building block circuit is intended for VLSI implementation as a single chip. Several building blocks and associated processor and memory chips form a self checking computer module with self contained input output and interfaces to redundant communications buses. Fault tolerance is achieved by connecting self checking computer modules into a redundant network in which backup buses and computer modules are provided to circumvent failures. The requirements and design methodology which led to the definition of the building block circuits are discussed

Improving timing verification and delay testing methodologies for IC designs

textThe task of ensuring the correct temporal behavior of IC designs, both before and after fabrication, is extremely important. It is becoming even more imperative as the demand for performance increases and process technology advances into the deep sub-micron region. This dissertation tackles the key issues in the timing verification and delay testing methodologies. An efficient methodology is presented to identify false timing paths in the timing verification methodology which utilizes ATPG technique and timing information from an ordered list of timing paths according to the delay information. This dissertation also presents a speed binning methodology which utilizes structural delay tests successfully instead of functional tests. In addition, it establishes a methodology which quantifies the correlation between the timing verification prediction and actual silicon measurement of timing paths. This quantification methodology lays the foundation for further research to study the impact of deep submicron effects on design performanceElectrical and Computer Engineerin

Reliable Low-Latency and Low-Complexity Viterbi Architectures Benchmarked on ASIC and FPGA

The Viterbi algorithm is commonly applied in a number of sensitive usage models including decoding convolutional codes used in communications such as satellite communication, cellular relay, and wireless local area networks. Moreover, the algorithm has been applied to automatic speech recognition and storage devices. In this thesis, efficient error detection schemes for architectures based on low-latency, low-complexity Viterbi decoders are presented. The merit of the proposed schemes is that reliability requirements, overhead tolerance, and performance degradation limits are embedded in the structures and can be adapted accordingly. We also present three variants of recomputing with encoded operands and its modifications to detect both transient and permanent faults, coupled with signature-based schemes. The instrumented decoder architecture has been subjected to extensive error detection assessments through simulations, and application-specific integrated circuit (ASIC) [32nm library] and field-programmable gate array (FPGA) [Xilinx Virtex-6 family] implementations for benchmark. The proposed fine-grained approaches can be utilized based on reliability objectives and performance/implementation metrics degradation tolerance

Measurements, Models, Systems and Design

531 s.

Empirical timing analysis of CPUs and delay fault tolerant design using partial redundancy

The operating clock frequency is determined by the longest signal propagation delay, setup/hold time, and timing margin. These are becoming less predictable with the increasing design complexity and process miniaturization. The difficult challenge is then to ensure that a device operating at its clock frequency is error-free with quantifiable assurance. Effort at device-level engineering will not suffice for these circuits exhibiting wide process variation and heightened sensitivities to operating condition stress. Logic-level redress of this issue is a necessity and we propose a design-level remedy for this timing-uncertainty problem. The aim of the design and analysis approaches presented in this dissertation is to provide framework, SABRE, wherein an increased operating clock frequency can be achieved. The approach is a combination of analytical modeling, experimental analy- sis, hardware /time-redundancy design, exception handling and recovery techniques. Our proposed design replicates only a necessary part of the original circuit to avoid high hardware overhead as in triple-modular-redundancy (TMR). The timing-critical combinational circuit is path-wise partitioned into two sections. The combinational circuits associated with long paths are laid out without any intrusion except for the fan-out connections from the first section of the circuit to a replicated second section of the combinational circuit. Thus only the second section of the circuit is replicated. The signals fanning out from the first section are latches, and thus are far shorter than the paths spanning the entire combinational circuit. The replicated circuit is timed at a subsequent clock cycle to ascertain relaxed timing paths. This insures that the likelihood of mistiming due to stress or process variation is eliminated. During the subsequent clock cycle, the outcome of the two logically identical, yet time-interleaved, circuit outputs are compared to detect faults. When a fault is detected, the retry sig- nal is triggered and the dynamic frequency-step-down takes place before a pipe flush, and retry is issued. The significant timing overhead associated with the retry is offset by the rarity of the timing violation events. Simulation results on ISCAS Benchmark circuits show that 10% of clock frequency gain is possible with 10 to 20 % of hardware overhead of replicated timing-critical circuit