Birth, Life, and Death in Microelectronic Systems

In order to exploit the technological promises of microelectronics, electronic system techniques must be developed so that defective portions of a system can be tolerated without system malfunction. Such defects might be introduced during manufacture (at birth), or cause errors during operation (life). The number of permanent failures which could be endured by a system before it fails completely will determine its lifetime (death). In this paper, an adaptive vote-taker is proposed which compares the outputs of paralleled (redundant) system parts in a binary system and determines the most probable answer based on past performance of the separate parts. Initially, the vote-taker assigns equal significance to each redundant part, and (in a binary system) requires that a simple majority of the parts be correct. With experience, the vote-taker continually reduces the weight (significance) of the outputs from those parts that make mistakes, thereby gradually eliminating the defective parts. Thus the vote-takers (which also may be paralleled if they are unreliable) act as automatic repairmen which delete defective parts of a system. System dependability and life expectancy can be made to exceed the dependability and average life expectancy of the component parts. The heart of an adaptive vote-taker is an element providing variable gain with memory. A variable resistor with memory (memistor), which uses electrochemical deposition or removal of copper to achieve the variable memory, has been successfully applied to this function.