Fast functional testing of delay-insensitive circuits

Although the advantages of delay-insensitive and self-timed circuits with respect to speed and operation are known, their advantages in terms of testing are not examined. We focus our attention on testing four-phase handshake signalling based circuits designed using Martin's method. Due to the distributed nature of the control part of a delay-insensitive circuit, it is possible to simultaneously test many non-interfering portions of the circuit, thereby substantially reducing the testing time. In order to ensure that the circuit performs in a delay-insensitive manner even during testing, certain OR gates in the synthesized circuit required to be replaced by OR/C blocks. An OR/C block operates as an OR gate during normal operation and as a C-element during testing. Identification of the OR gates to be replaced by OR/C blocks and the generation of test sequences is performed by analyzing the program flow graph of the given circuit.