A built-in self-test (BIST) method and apparatus for digital integrated circuits (ICs) and for systems including multiple ICs, measures signal propagation delays in combinational and sequential logic, set-up and hold times, and tri-state enable/disable times, from any circuit node to any other circuit...http://www.google.com.au/patents/US5923676?utm_source=gb-gplus-sharePatent US5923676 - Bist architecture for measurement of integrated circuit delays
