The Coupling Model for Function and Delay Faults

Abstract

We propose a high-level fault model, the coupling fault (CF) model, that aims to cover both functional and timing faults in an integrated way. The basic properties of CFs and the corresponding tests are analyzed, focusing on their relationship with other fault models and their test requirements. A test generation program COTEGE for CFs is presented. Experiments with COTEGE are described which show that (reduced) coupling test sets can efficiently cover standard stuck-at-0/1 faults in a variety of different realizations. The corresponding coupling delay tests detect all robust path delay faults in any realization of a logic function.

Robust Coupling Delay Test Sets

“…The CDTS concept was proposed in [17] for singlemodule circuits, and its application extended to general modular circuits in [18]. However, the application of coupling delay tests (CDTs) to a multi-module circuit may greatly reduce delay fault coverage compared to testing the circuit as a single module because only single input changes are allowed in a CDT.…”

“…The gross delay fault model [8] requires all adjacent vector pairs as tests, which results in huge test sets (n2 n tests for an n-input module) although it covers all delay faults [17]. The function-robust delay fault model [9] covers all robust path delay faults [11] with smaller test sets.…”

“…The coupling delay test set (CDTS) of a function z is composed of all singleinput-change pattern pairs that have different output values of z. The CDTS of z is necessary and sufficient to detect all robust path delay faults in any realization of z [17].…”

“…In this paper, a small and high-coverage test set called a robust coupling delay test set (RCDTS) is derived from the CDTS proposed in [17]. CDTS size is reduced by exploiting a partial ordering relationship among delay tests in certain implementations called ařrestrictedąś gate networks.…”

Efficient RTL Coverage Metric for Functional Test Selection

“…The coupling fault (CF) model [20] is also defined by an input/output pair. However, detection of a CF requires application of all vectors that satisfy the Boolean difference of the output w.r.t.…”