Introduction
Automatic test pattern generation (ATPG) systems are tools for generating tests for digital circuits after they are produced.
Testing very-large-scale integrated circuits with a high fault coverage is a difficult task because of complexity. Different ATPG methods have to be applied to combinatorial and sequential circuits.
Psuedorandom test generation is the simplest method of creating tests. It uses a pseudorandom number generator to generate test vectors.
Algorithmic Methods
Several computer generated methods to create test patterns have been created.
- 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) is an improvement over PODEM. It limits the ATPG search space to reduce computation time and accelerates backtracing.
See also
- Design for Test (DFT)
- Fault model
- ASIC
- VHSIC