High-Level Test Synthesis for Delay Fault Testability

A high-level test synthesis (HUTS) method targeted for delay fault testability is presented. The proposed method, when combined with hierarchical test pattern generation for embedded modules, guarantees 100% delay test coverage for detectable faults in modules. A study on the delay testability problem in behavior level shows that low delay fault coverage is usually attributed to the fact that two-pattern test for delay testing cannot be delivered to modules under test in consecutive cycles. To solve the problem, the paper proposed an HUTS method that ensures valid test pairs can be sent to each module through synthesized circuit hierarchy. Experimental results show that this method achieves 100% fault coverage for transition faults in functional units, while the fault coverage in circuits synthesized by LEA-based allocation algorithm is rather poor. The area overhead due to this method ranges from 2% to 10% for 16-bit datapaths