A novel delay fault testing methodology using on-chip low-overhead delay measurement hardware at strategic probe points

We propose a delay fault testing methodology using on-chip delay measurement hardware. We have designed a process-tolerant, low-overhead delay measurement hardware and developed an algorithm to judiciously insert the hardware at internal nodes of logic blocks. Experimental results for a set of ISCAS89 benchmarks show up to 16.9% improvement in transition fault coverage and up to 10.5% increase in the number of detected faults for segment delay fault model, with fixed test length. The reduction in test length is up to 59% for transition fault, with fixed target coverage. The delay and area overhead due to additional DFT logic is limited to 2% and 4% respectively.