An Ultra-Low Cost Multilayer RAM in Quantum-Dot Cellular Automata

Quantum-dot cellular automata (QCA) is an alternative nanotechnology to traditional CMOS technology. In theory, circuits in QCA have the advantages of lower power consumption, higher integration density and switching frequency than circuits based on CMOS. Random access memory (RAM) circuits that are critical in designing large memory circuits have been explored. In this brief, a novel loop-based RAM cell with asynchronous set and reset, by using a new 2-1 multiplexer and D-latch, is proposed. Efficient 1 x 4 RAM and 4 x 4 RAM with three-layer structure are constructed. The proposed RAM cell has 35% improvement in both circuit footprint and cost, compared with an existing best scheme. The 1 x 4 RAM has less cells, delay and area than the previous designs with the same circuit scheme. The 4 x 4 RAM and m x n RAM show that the proposed RAM cell has excellent scalability for designing complex circuits. Functional correctness of the proposed designs has been proved by using QCADesigner 2.0.3.