A review on regular clocking scheme in quantum dot cellular automata

Abstract

Quantum-dot cellular automata (QCA) is a novel and emerging nanotechnology that explores the potential of using quantum dots as information carriers in computing devices. The information transfer, as well as timing synchronization of the QCA circuit, is controlled by clocks. Despite this, most of the work done in QCA does not consider the proper layout of the underlying clocking circuit required. Hence, it ends up with QCA circuits with irregular clock zones, which is not suitable for fabrication. However, for efficient design and to provide proper routing options within the clock zones, a regular, scalable clocking scheme is needed. Without a well-defined and regular clocking zone, the QCA circuit designs are incomplete and not a standard fabrication candidate. In this regard, several regular clocking schemes in QCA are discussed in the literature. In this survey, a systematic review of those clocking schemes will be investigated. A detailed comparison of these schemes is also discussed based on design architecture and fabrication point of view.