Self-Checking Circuits

With the increasing complexity of digital systems, ensuring the reliability of computations has become an important issue. A number of methods have been presented for the design of fault-tolerant systems. The first step in such a design is to detect faults. We would like to detect the faults as soon as they occur in order to prevent data contamination. An important concept which allows us to detect transient as well as permanent faults is the self-checking concept. Since transient faults have begun to play a dominant role in this era of VLSI circuits, they can no longer be ignored. As the name implies, a self-checking circuit is capable of automatically exposing its own faults. Another advantage of self-checking circuits is that software diagnostic programs can be simplified or even eliminated. This concept is becoming more and more attractive because the area overhead on a chip required to implement this concept is going down with the increase in the complexity of the chips.