An Overview on RAM Memories in QCA Technology
AbstractQuantum-dot Cellular Automata (QCA) is a computational technology that can be used to construct nanoscale circuits. Nowadays, this technology is a good alternative for CMOS technology due to features such as high speed, low occupied area and low power consumption. Mmemory is utilized as one of the basic elements in digital circuit design hence the design and optimization of high-speed RAM memory cells have become one of the most attractive research areas; in the realm of QCA. In this paper, we present a comprehensive investigation on RAM memories. For this purpose, the proposed schemes in terms of functionality, the number of cell consumption, and latency are implemented and compared using QCA Designer software. The results show that some of the proposed schemes show better performance in terms of parameters such as occupied area and delay. Nevertheless, they are still suffering from less stability; hence introducing an optimum scheme is infeasible.
Tougaw P. D. and C. S. Lent, (1994). “Logical Devices Implemented Using Quantum Cellular Automata,” Journal of Applied Physics, Vol. 75, No. 3, pp. 1818–1825.
 A. Shahini Shamsabadi, B. Shahgholi Ghahfarokhi, K. Zamanifar, A. Vafaei, Applying inherent capabilities of quantum-dot cellular automata to design: D ﬂip-ﬂop case study, J. Syst. Archit. 55 (2009) 180–187 (Elsevier).
 K. Walus, A. Vetteth, G.A. Jullien, V.S. Dimitrov, RAM design using quantum- dot cellular automata, in: Technical Proceedings of the Nanotechnology Conference and Trade Show, 2, 2003, pp. 160–163.
 X. Yang, L. Cai, X. Zhao, Low power dual-edge triggered ﬂip-ﬂop structure in quantum dot cellular automata, Electron. Lett. 46 (2010) 825 (–626).
 A. Vetteth, K. Walus, V.S. Dimitrov, G.A. Jullien, Quantum-Dot Cellular Auto- mata of Flip-Flops, ATIPS Laboratory 2500 University Drive, N.W., Calgary, Alberta, Canada T2N 1N4, 2003.
 V. Vankamamidi, M. Ottavi, F. Lombardi, A serial memory by quantum-dot cellular automata (QCA), IEEE Trans. Comput. 57 (2008) 606–618.
 D. Berzon, T.J. Fountain, A memory design in QCAs using the squares m, in: Proceedings of the Great Lakes Symposium, VLSI, 1999,pp. 166–169.
M.A. Dehkordi, A. Shahini Shamsabadi, B. Shahgholi Ghahfarokhi, A. Vafaei, RAM novel cell designs based on inherent capabilities of quantum-dot cellular automata, Microelectron. J. 42 (2011) 701–708 (Elsevier).
[10 X. Yang, L. Cai, X. Zhaho, N. Zhang, Design and simulation of sequential circuits in quantum-dot cellular automata: falling edge-triggered ﬂip-ﬂop and counter study, Microelectron. J. 41 (2010) 56–63 (Elsevier).
 S. Hashemi, K. Navi, New robust QCA D ﬂip ﬂop and memory structures, Microelectron. J. 43 (2012) 929–940 (Elsevier)
 Shaahin Angizi a, Soheil Sarmadi a, SamiraSayedsalehi a, KeivanNavi, Design and evaluation of new majority gate-based RAM cell in quantum-dot cellular automata,Microelectronics Journal 46(2015)43–51.