3-bit Shift Register using QCA Nanotechnology

Quantum-dot Cellular Automata (QCA) is a new emerging nanotechnology that has been proven to be an improved alternative to complementary metal oxide semiconductor (CMOS) technology. It consists of a group of cells that can perform computational functions when combined and arranged in a particular manner. The Flip-Flops are widely affiliated with the circuits of logical and arithmetic unit structures that are used for the processors. Data (D) Flip-Flop is the most important and widely used Flip-Flop among all different types due to its better performance and efficiency. Hence, an efficient D Flip-Flop needs to be developed using QCA nanotechnology. This paper proposes a new design for D Flip-Flop in QCA nanotechnology. The proposed D Flip-Flop has 28 quantum cells and covers an area of 0.03 µm2. Furthermore, the paper presents a new design for a 3-bit Shift Register using the proposed D Flip-Flops in QCA nanotechnology keeping in mind the importance of the same in storing and transferring multiple bits of data. The proposed D Flip-Flop and the 3-bit Shift Register are compared with the existing QCA-based designs. The proposed Shift Register has 100 quantum cells and covers an area of 0.11 µm2. The comparison concludes that the proposed D Flip-Flop and the 3-bit Shift Register have used a lesser number of QCA cells and covered smaller areas than the previous works. The proposed designs have been designed in a single layer without any crossover.