Fault detection in multiple controlled Fredkin circuits

Testing is an essential process to validate the truthful functionality of logic circuits, devices, and systems. It accounts a large overhead in terms of additional hardware, time, and manpower which dramatically enhance overall cost of manufacturing. The efficacy of multiple control Fredkin (MCF) gates towards both online and offline testing paradigms is demonstrated here by exploiting their parity preserving and conservative properties. The authors introduce (i) a method of testing MCF circuits for the detection of bit-flip faults online; (ii) deterministic approaches for the identification of stuck-at, bridging, missing gate, and cross-point faults; and (iii) three test sets of size 2, n, and $2\lpar n - 2\rpar $2(n−2) for the detection of these faults off-line. Experiments are performed on a set of benchmarking circuits to demonstrate the effectiveness of the proposed methods in terms of test overhead and fault coverage. Online testable circuits are formulated on account of 0.5% of overhead in terms of considered cost metrics and an average reduction up to 61% is calculated with respect to existing work in the area. The test sets show completeness for the detection of all considered fault models. Fault simulations for both the presented testing methodologies are carried out which shows 100% coverage.