Testability of SPP Three-Level Logic Networks in Static Fault Models

Full testability is a desirable property for a minimal logic network. The classical minimal two-level sum of products (SOP) networks are fully testable in some standard fault models. In this paper, the authors investigate the testability of recently introduced three-level logic forms sum of pseudoproducts (SPP), which allow the representation of Boolean functions with much shorter expressions than two-level forms. The authors study their testability under static fault models (FMs), i.e., the stuck-at-fault model (SAFM) and the cellular fault model (CFM). For SPP networks, several minimal forms can be considered. While full testability can be proven in the SAFM for some forms, SPP networks in the CFM are shown to contain redundancies. Finally, the authors propose a method for transforming nontestable networks into testable ones. In the SAFM, the resulting irredundant networks are still minimal. The experimental results are given to demonstrate the efficiency of the approach.