Summary
The QCA technology is a promising emerging technology at nano‐scale for replacing CMOS technology. Shift register has a vital role in communication networks and digital electronic circuits that are the main components of integrated circuits and memory. In this study, novel and efficient delay circuit (pseudo‐D‐Latch) is designed. Then, 3‐, 4‐, and 5‐bit SISO QCA shift register architectures are developed and evaluated in single layer, 3‐layer and 5‐layer using the designed delay circuit. The designed architectures are evaluated using QCADesigner‐E tool version 2.2. The results demonstrate that the pseudo‐D‐Latch circuit contains 17 cells and 0.01 μm2 area. The 3‐, 4‐, and 5‐bit single layer SISO QCA shift register architecture contains 63 (0.05 μm2), 85 (0.66 μm2), and 107 (0.08 μm2) cells (area), respectively. The 3‐ and 4‐bit 3‐layer SISO QCA shift register architecture contains 63 (0.03 μm2) and 84 (0.03 μm2) cells (area), respectively. The 3‐ and 5‐bit 5‐layer SISO QCA shift register architecture contains 62 (0.02 μm2) and 105 (0.032 μm2) cells (area), respectively. These results show that the designed QCA architectures provide improvements compared with other SISO QCA architectures.