FREEZE: a new approach for testing sequential circuits

The authors present a new approach for testing sequential circuits which extends the classical concept of a test sequence. The classical approach applies only one vector in every state. In contrast, the new approach temporarily disables the sequential behavior of the circuit by holding the clock inactive and applies a group of vectors in every state. In this way many faults can be combinationally detected. A test generation algorithm called FIRST (fault-independent rapid sequential test generator) was developed based on the new approach. FIRST detected a large percentage of the faults that were detected by a conventional fault-oriented sequential test generator in less CPU time and with shorter sequences.<>