Fault-tolerant carry look-ahead adder architectures robust to multiple simultaneous errors

Abstract

Currently, the demand for reliable and high performance computing is increasing due to the enlarging susceptibility of computing circuits to different environmental effects, and the advent of diverse computation-based applications. Arithmetic operators, as the main building blocks of the processing units in computing systems, are exposed to different types of single or multiple errors incurred by different faults which can seriously damage the whole system. In this paper, a new approach is presented to achieve fault-tolerant carry look-ahead adder architectures, much more efficient than the conventional methods, with the characteristic of robustness against multiple simultaneous errors. The proposed method is based on revising the carry generation block to achieve multiple error correction capability, and utilizing a modified parity prediction-based method that in combination with the proposed error correction scheme leads to multiple error detection capability. Verified by simulations, analytical assessments show that, as well as correcting or detecting all single permanent or transient errors, multiple simultaneous errors in the new carry look-ahead adders are corrected or at least detected with a high probability independent of the number of errors. Apart from having more reliability against multiple errors, these adders require lower area overheads compared to the state of the art designs as well as conventional fault-tolerant methods.