Online Testable Efficient Latches for Molecular QCA Based on Reversible Logic

Abstract

Quantum computer is very advanced technology in upcoming era and can capable to solve any complex problem with very fast computation power. The proposed models for quantum computation are quantum dot cellular automata (QCA). The molecular QCA has the tendency to high error rates. In case of molecular quantum dot cellular automata, the main objective of circuit design is the reduction of circuit area with wanted functional behavior. In this article, we propose the efficient design of online testable latches based on reversible logic for molecular QCA that is very much cost-effective respect to circuit area and other parameters. We use reversible gates having conservative property; i.e., capability for producing the equal number of 1s in output bits as input bits. So, conservative logic gates are subset of parity preserving reversible gate. Fault patterns of used conservative logic gate are analyzed for single stuck-at faults in molecular QCA circuit. Our proposed latches are able to examine single stuck-at fault, missing/additional QCA cell defect online, including permanent or transient fault in molecular QCA and efficient respect to circuit area. The designs of QCA layouts for various latches are presented and verified using QCA Designer and the Verilog HDL library of QCA devices is used to present HDLQ design tool.