Testing and defect tolerance: a Rent's rule based analysis and implications on nanoelectronics

Defect tolerant architectures will be essential for building economical gigascale nanoelectronic computing systems to permit functionality in the presence of a significant number of defects. The central idea underlying a defect tolerant configurable system is to build the system out of partially perfect components, detect the defects and configure the available good resources using software. In this paper we discuss implications of defect tolerance on power area, delay and other relevant parameters for computing architectures. We present a Rent's rule based abstraction of testing for VLSI systems and evaluate the redundancy requirements for observability. It is shown that for a very high interconnect defect density, a prohibitively large number of redundant components are necessary for observability and this has adverse affect on the system performance. Through a unified framework based on a priori wire length estimation and Rent's rule we illustrate the hidden cost of supporting such an architecture.