Single Soft Errors Research Articles

Effect of Soft Errors in Iterative Learning Control and Compensation using Cross-layer Approach

In this paper, we study the effects of radiation-induced soft errors in iterative learning control(ILC) and present the compensation techniques to make the ILC systems robust against soft errors. Soft errors are transient faults, which occur temporarily in memories where the energetic particles strike the sensitive region in the transistors mainly under abnormal conditions such as high radiation, high temperature, and high pressure. These soft errors can cause bit value changes without any notification to the controller, affect the stability of the system, and result in catastrophic consequences. First, we investigate and analyze the effects of soft errors in the ILC systems. Our analytical study shows that when a single soft error occurs in the output data from the ILC, the performance of the learning control is significantly degraded. Second, we propose novel learning methods by incorporating the existing techniques across the system abstraction levels in the ILC to compensate for soft-error-induced incorrect output. The occurrence of soft errors is estimated by using a monotonic convergence of the erroneous outputs in a cross-layer manner, and our proposed methods can significantly reduce these negative impacts on the system performance. Under the assumption of soft error occurrence, our analytic study has proved the convergence of the proposed methods in the ILC systems and our simulation results show the effectiveness of the proposed methods to efficiently reduce the impacts of soft-error-induced outputs in the ILC systems.

Self-Repairing Digital System Based on State Attractor Convergence Inspired by the Recovery Process of a Living Cell

Increasing attention is being paid to soft errors due to their high incidence. Although various approaches have been developed to mitigate such soft errors in digital storage components such as latches and flip-flops, most of them can detect only a single soft error and correct it only in limited cases, with a high overhead of hardware resources. In this paper, we propose a new self-repairing digital system based on the state attractor-converging mechanism, inspired by the recovery process of a living cell. To implement the state attractor-converging mechanism, the proposed system introduces additional states other than a working state, such that any abnormal transition to an additional state caused by a soft error can be recovered immediately. Moreover, the proposed system employs a reconfiguration method that enables a system with an erroneous state to be recovered regardless of any working state of the system while having a similar hardware overhead compared with the existing systems. From simulation analysis and experimental verification, we show that the proposed system can detect and correct not only a single soft error without any restriction but also two simultaneous soft errors under a few conditions. Furthermore, the proposed system can recover a soft error occurring in the control hardware used for error detection and correction, which is not possible with any other existing approaches.

An Efficient Technique to Protect Serial Shift Registers Against Soft Errors

This brief presents a technique to efficiently correct single soft errors in serial shift registers. The proposed scheme uses two copies of the shift register. To achieve error correction, data are convolutionally encoded at the input of one of the copies and are decoded at its output. This processing ensures that in that copy, any error affecting a single bit will corrupt its output for multiple cycles. On the other hand, a single-bit error in the original copy will corrupt its output only for one cycle. Therefore, the error patterns can be used to identify the copy that has suffered the error and, consequently, to correct the error. The proposed technique has been implemented in a Hardware Description Language and implemented in a 45-nm library. A fault injection tool has been used to evaluate the effectiveness of the proposed scheme, showing that it can correct all single soft errors. The cost of the proposed approach in terms of circuit area has been compared with a traditional triple-modular redundancy implementation. The results show significant cost reductions, which approach a factor of 33% for large shift registers.

Offset DMR: A Low Overhead Soft Error Detection and Correction Technique for Transform-Based Convolution

A novel concurrent soft error detection and correction scheme is introduced for parallel hardware implementations of transform-based convolution. The proposed technique is based on the structure of radix-2 Fast Fourier Transforms (FFT) of length 2n where n is an integer. The scheme can provide up to 100 percent detection and correction of isolated single soft errors in the convolution at the cost of little more than double the system area, rather than triple, as is required when using conventional Triple Modular Redundancy (TMR).

Structural DMR: A Technique for Implementation of Soft-Error-Tolerant FIR Filters

In this brief, an efficient technique for implementation of soft-error-tolerant finite impulse response (FIR) filters is presented. The proposed technique uses two implementations of the basic filter with different structures operating in parallel. A soft error occurring in either filter causes the outputs of the filters to differ, or mismatch, for at least one sample. The filters are specifically designed so that, when a soft error occurs, they produce distinct error patterns at the filter output. An error detection circuit monitors the basic filter outputs and identifies any mismatches. An error correction circuit determines which filter is in error based on the mismatch pattern and selects the error-free filter result as the output of the overall error-protected system. This technique is referred to as structural dual modular redundancy (DMR) since it enhances traditional DMR to provide error correction, as well as error detection, by means of filter modules with different structures. The proposed technique has been implemented and evaluated. The system achieves a soft error correction rate of close to 100% for isolated single soft errors and has a logic complexity significantly less than that of conventional triple modular redundancy.