PPA Optimization of Test Points in Automotive Designs

Automotive designs demand the highest possible test coverage for safety and reliability. One approach is to add as many test points as possible to the circuit. To avoid increasing the die size, test point sharing can be used to maximize the number of test point nodes while using fewer test point flops. While test point sharing reduces area overhead, extra wiring is needed leading to congestion which again limits the number of test points that can be added. This paper presents a method to reduce wiring congestion when sharing a large number of test points. Our method also reduces the impact sharing can have on fault coverage. Test point sharing is optimized in the physical implementation tool to reduce wiring and congestion leading to improvements in PPA. Results from five automotive designs show up to a 67% reduction in wiring for test point logic, an average 24% reduction in congestion, and improvements in PPA. Alternatively, one can increase the number of test points and achieve a 1.62% improvement in LBIST coverage without introducing additional congestion or impacting PPA.