Designing Bi-directional Counters Using Quantum-dot Cellular Automata Nanotechnology

One of the major problems in designing highly compact integrated circuits is the power consumption of the circuits. Therefore, several technologies have been introduced to overcome the problems facing MOSFET technology. One of these technologies is the Quantum-Dot Cellular Atomata (QCA), which has several advantages. In this paper, we focus on computational logic gates based on the T-Latch circuit. T-latch is the basis of many circuit in arithmetic logic unit (ALU). The proposed structure for T-latch has a lower number of cells, occupied area and lower power consumption than existing methods. In the proposed T-Latch, compared to previous best designs, 6.45% cross section area and 44.49% power consumption were reduced. Also in this paper, for the first time a T-latch with reset terminal and a T-Latch with both set and reset terminals were designed. In addition, using the proposed T-latch, a 3-bit bidirectional up-down counter which consists of 204 quantum cells, 0.26 µm2 cross-sectional area, delay of 5.25 clock cycles, a three-bit up-down counter with a reset pin and a three-bit up-down counter with set and reset terminals were made. The proposed up-down circuits are designed for the first time in QCA technology. All the design and simulation results are done in QCADesigner software.