Quantum Cellular Automata (QCA) is an alternative promising nanotechnology for semiconductor transistor based technology. QCA benefits from several features such as high speed, low power consumption and can be used for extremely dense structures. One of the important issues in arithmetic circuits is design of FULL ADDER/FULL subtractor (FA/FS respectively). Our main contribution in this paper is proposing a one-bit FA/FS which benefits from less cell counts compared to the state-of-the-art technologies. The proposed QCA FA/FS ameliorate the number of cells in comparison with the best FA/FS studied in the literature. As well as the mentioned feature, temperature analysis of suggested circuit shows that our design is more tough compared to the previous works.

Nowadays, the portable multimedia electronic devices, which employ signal-processing modules, require power aware structures more than ever. For the applications associating with human senses, approximate arithmetic circuits can be considered to improve performance and power efficiency. On the other hand, scaling has led to some limitations in performance of nanoscale circuits. Accordingly, Carbon Nanotube Field Effect Transistors have gotten a widespread attention as the most appropriate replacement for MOSFETs. In this paper, an imprecise FULL ADDER cell based on CNFET minority gates is introduced. Evaluation and comparison of the minority-based and the-state-of-the-art imprecise FULL ADDERs in terms of average power dissipation, delay and power delay product (PDP) are done. The error distance (ED), normalized error distance (NED) and PDP-NED product metrics are also considered for assessing the accuracy of the reviewed circuits. The HSPICE simulations, conducted using Stanford 32nm CNFET model, indicate that the minority-based design outperforms the other designs in terms of performance and error tolerance.

This study introduces a reversible optical FULL ADDER. Also optical NOT and NOR gates are implemented through Electro-Absorption-Modulator / Photo Detector (EAM/PD) pairs, were utilized for fulfilling reversible R gate. Then, reversible FULL ADDER was designed based on the proposed reversible optical R gate. The operation of the suggested FULL ADDER was simulated using Optispice and it was found that the delay time in comparison with VLSI implemented circuit has remarkably improved.

Quantum-dot cellular automata (QCA) are an emerging technology and a possible alternative for semiconductor transistor based technologies. A novel fault-tolerant QCA FULL-ADDER cell is proposed: This component is simple in structure and suitable for designing fault-tolerant QCA circuits. The redundant version of QCA FULL-ADDER cell is powerful in terms of implementing robust digital functions. By considering two-dimensional arrays of QCA cells, fault tolerance properties of such block FULL-ADDER cell can be analyzed with misalignment, missing and dislocation cells. To verify the functionality of the proposed device, some physical proofs and computer simulations using QCADesigner are provided. Both simulation results and physical relations confirm our claims and its usefulness in designing fault-tolerant digital circuits.