Toward Quaternary QCA: Novel Majority and XOR Fuzzy Gates

As an emerging nanotechnology, quantum-dot cellular automata (QCA) has been considered an alternative to CMOS technology that suffers from problems such as leakage current. Moreover, QCA is suitable for multi-valued logic due to the simplicity of implementing fuzzy logic in a way much easier than CMOS technology. This paper uses a quaternary cell with two isolated layers because of requiring three particles to design this quaternary cell. Moreover, due to the instability of the basic gates, the three particles cannot be placed in one layer. The first layer of the proposed two-layer cell includes a ternary cell and the second one includes a binary cell. It is assumed that the overall polarization of the quaternary QCA (QQCA) cell is determined as the combined polarization of the two layers. The proposed QQCA cell can also be implemented in one layer. Simulations of the QQCA cell are performed based on analytical calculations. Moreover, a majority fuzzy gate, an XOR fuzzy gate, and a crossbar structure are simulated.