Error Correction Coding for Electronic Circuits

Abstract

Digital electronic circuits are subject to many types of error. Considering the effect of such errors on the circuit functionality, they can be classed as permanent, transient or intermittent. Permanent (or “hard”) errors disrupt the functionality of the circuit for its entire lifetime [1]. An example of a hard error is a stuck at one/zero fault in a logical gate, in which the output is fixed to a logical value regardless of the values of the inputs. Permanent errors can be caused, for example, by manufacturing defects, aging, or radiation effects. Transient (or “soft”) errors only affect the functionality of the circuit for a short time. An example of a transient error is a radiation-induced soft error, in which a particle impacts the circuit and changes the logical value of one circuit node [2]. Transient errors can also be caused by noise or crosstalk. The circuit functions correctly after the error event, but if an incorrect value is stored in a register or memory then the system state can be erroneous. Intermittent errors are those which affect a circuit node in such a way as to cause errors frequently but not constantly [3]. These errors are commonly caused by marginal or unstable behavior, which may or may not cause an error, depending on the conditions.