Design For Testability of QCA Logic under Stuck-at-value Fault Model

摘要

Quantum Dot Cellular Automata (QCA) has recently attracted interest as an alternate logic paradigm. Though QCA has demonstrated functional enhancement with respect to CMOS logic, its fabrication is yet ill defined and prone to manufacturing defects. In this regard we present a comprehensive Design for Testability of combinational QCA logic irrespective of size and complexity. We show that by adopting the AND-OR design scheme, and introducing a block of 'Test Enable' Majority Voters inserted between inputs to the AND-OR block and the literal outputs of the inverting block with primary inputs, any logic is fully testable with only two test vectors. In hierarchical design, cascading individual modules reduces the observability of the fault. We address this issue and propose a single fault propagation path to detect any fault otherwise masked by the modular nature of the original logic. To verify our approach we use a modular 4-bit adder.