Algorithmic Methods
Testing very-large-scale integrated circuits with a high fault coverage is a difficult task because of complexity. Therefore many different ATPG methods have been developed to address combinational and sequential circuits.
- Early test generation algorithms such as boolean difference and literal proposition were not practical to implement on a computer.
- The D Algorithm was the first practical test generation algorithm in terms of memory requirements. The D Algorithm introduced D Notation which continues to be used in most ATPG algorithms.
- Path-Oriented Decision Making (PODEM) is an improvement over the D Algorithm. PODEM was created in 1981 when shortcomings in D Algorithm became evident when design innovations resulted in circuits that D Algorithm could not realize.
- Fan-Out Oriented (FAN Algorithm) is an improvement over PODEM. It limits the ATPG search space to reduce computation time and accelerates backtracing.
- Methods based on Boolean satisfiability are sometimes used to generate test vectors.
- Pseudorandom test generation is the simplest method of creating tests. It uses a pseudorandom number generator to generate test vectors, and relies on logic simulation to compute good machine results, and fault simulation to calculate the fault coverage of the generated vectors.
Read more about this topic: Automatic Test Pattern Generation
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