Optimized implementation of pseudo-random bit generation and shift register structures in QCA technology

• The most important innovations of this article are: • An innovative new design of rising edge sensitive D flip-flop with the minimum number of cells • A new four-bit LFSR design with low power consumption • New eight-bit LFSR design for the first time in QCA technology • New and optimized four-bit shift register design with reset capability Quantum-dot Cellular Automata (QCA) represents a promising direction in nanoscale circuit design, utilizing quantum effects between closely spaced quantum dots to implement digital logic without traditional transistors. This technology facilitates the creation of dense and energy-efficient digital systems. This work proposes four novel QCA-based structures are developed and analyzed, including a rising edge-sensitive D flip-flop, four-bit and eight-bit linear feedback shift registers (LFSRs), and a four-bit shift register equipped with reset functionality. The proposed designs prioritize reductions in cell count, occupied area, propagation delay, and energy consumption. For instance, the D flip-flop includes 28 cells with an area footprint of 0.02 µm². The four-bit and eight-bit LFSRs utilize 145 and 281 cells, respectively, corresponding to areas of 0.16 µm² and 0.2 µm². The reset-enabled four-bit shift register comprises 104 cells and occupies 0.07 µm². These findings suggest that the proposed circuits offer improved design efficiency compared to prior work. Functional validation and energy analysis were performed using QCADesigner version 2.0.3 and QCAPro simulation platforms.