Using transition test to understand timing behavior of logic circuits on UltraSPARCTM T2 family

Delay test is crucial for finding slow paths and slow ICs, both during bringup and during speed binning. Path delay test has traditionally been considered to be superior in finding slow paths. This paper describes our experiments indicating that this is not always the case. For the UltraSPARC T2 microprocessor series we found that transition delay test often ran slower, was more effective in finding the root cause of the slow path, and correlated well with functional diags also used for speed binning. Transition test does a better job finding delay issues related to the impact of simultaneous switching and coupling noise on chip speed. We used transition test to measure the impact on chip timing of voltage, temperature, and we also used it to confirm the results of improving slow paths.