Timing-independent testing of crosstalk in the presence of delay producing defects using surrogate fault models

All previous approaches for generating tests for crosstalk slow-downs are timing-dependent, i.e., they use the nominal values of gate and wire delays while generating tests. None of these methodologies can be used when a crosstalk slow-down must be considered in the presence of process variations and delay producing defects, since such variations and defects change the delay values from the nominal. We present the first timing-independent approach to generate tests for crosstalk slow-downs. The framework is based upon defining a set of surrogates for each crosstalk slow-down target and generating a test for each surrogate. The timing-independent conditions that a test for each surrogate must satisfy are presented. Under the pin-to-pin delay model, we prove that a set of two-vector sequences that covers every surrogate for a crosstalk slow-down target is guaranteed to detect the target, even in the presence of arbitrary delay variations and delay producing defects. We present a method to identify the crosstalk targets and surrogates for which tests must be generated as well as a test generator that we have implemented. We present extensive experimental results using combinational parts of ISCAS 89 circuits.