Cascade of two-input nonlinear logic in designing space compression networks in VLSI

Realizing aliasing-free space compressor for built-in self-testing of very large scale integration circuits and systems is of immense practical significance, especially due to the design paradigm shift in recent years from system-on-board to system-on-chip. This paper explores and provides new results on extending the scope of a recently developed approach to synthesizing aliasing-free space compaction hardware targeting particularly embedded cores-based system-on-chips for single stuck-line faults, utilizing well known concept from conventional switching theory, viz. that of compatibility relation as used in the minimization of incompletely specified sequential machines. For a pair of response outputs of the circuit under test, the method uses the notion of fault detection compatibility and conditional fault detection compatibility (conditional upon some other response output pair being simultaneously fault detection compatible) with respect to two-input AND/NAND nonlinear logic. The process is illustrated with development details of space compressors for the International Symposium on Circuits and Systems or ISCAS 85 combinational and ISCAS 89 full-scan sequential benchmark circuits (results on full-scan sequential circuits though not included in the paper) using simulation programs ATALANTA and FSIM, showing the relevance of the technique from the viewpoint of simplicity, resultant low area overhead and full fault coverage for single stuck-line faults, thereby making it an ideal choice in actual design environments.