Testable MUXED-D Scan Cell in Quantum-dot Cellular Technology

Document Type : Original Article


1 Department of Electrical Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran

2 Department of Computer Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran


Quantum-dot Cellular Automata (QCA) is one of the new nanoscale technologies which proposed for future circuits. This  technology has been remarkable due to its faster speed, lower size and reduction in power consumption compared to CMOS technology. Many circuits have been implemented in this technology including shift registers, they are one of the most important digital circuits for many applications. With the development of QCA technology, it is important to provide testing methods for testing these circuits.4-Bit serial shift registers designed in previous research were not capable of testing their output. In this paper,  MUXED-D scan cell concept helps to detect the errors before fabrication and reduce time and cost. The MUXED-D scan consists of a D flip-flop and a 2 to 1 multiplexer. Compared to the latest scan cell, we have seen a 25 % decrease in occupied area and 15.62 % decrease in the number of cells and latency from 1 to 0.75 clock cycle. In general, this scan cell circuit is made of 27 cells with an area of 0.03 µm2 and a latency of 3 clock cycles. The proposed shift register includes four scan cells with two inputs which includes main and test signals. In fact, the number of cells used for the last 4-bit serial testable shift register in this design is 324, 0.39µm2 occupied area and the corresponding delay is 6.75 clock cycles. In order to verify this performance, QCA simulator is used.


  1. Lim, L.A., Ghazali, A., Yan, S.C.T. and Fat, C.C., "Sequential circuit design using quantum-dot cellular automata (QCA)", in 2012 IEEE International Conference on Circuits and Systems (ICCAS), IEEE. (2012), 162-167.
  2. Lent, C.S., Tougaw, P.D., Porod, W. and Bernstein, G.H., "Quantum cellular automata", Nanotechnology, Vol. 4, No. 1, (1993), 49, doi: 10.1088/0957-4484/4/1/004.
  3. Sabbaghi-Nadooshan, R. and Kianpour, M., "A novel qca implementation of mux-based universal shift register", Journal of Computational Electronics, Vol. 13, No. 1, (2014), 198-210, doi: 10.1007/s10825-013-0500-9.
  4. Wang, L.-T., Wu, C.-W. and Wen, X., "Vlsi test principles and architectures: Design for testability, Elsevier, (2006).
  5. Harshitha, S., Dhanush, T. and Premananda, B., "A novel qca based compact scan flip-flop for digital design testing", International Journal of Engineering and Advanced Technology, Vol. 9, No. 1, (2019), 6681-6686, doi: 10.35940/ijeat.A1973.109119.
  6. Pooja, M., Shetty, G.S., Datta, V.S. and Suchitra, M., Design of set d flip-flop and scannable set d flip-flop with optimized area, in Advances in communication, signal processing, vlsi, and embedded systems. 2020, Springer.239-245.
  7. Goswami, M., Kumar, B., Tibrewal, H. and Mazumdar, S., "Efficient realization of digital logic circuit using qca multiplexer", in 2014 2nd International Conference on Business and Information Management (ICBIM), IEEE., (2014), 165-170.
  8. Shantala, G. and Karthik, P., "Design and implementation of scan flip-flop for processor using qca technology", International Journal of Control and Automation, Vol. 10, No. 8, (2017), 41-52, doi: 10.14257/ijca.2017.10.8.04.
  9. Lent, C.S., Liu, M. and Lu, Y., "Bennett clocking of quantum-dot cellular automata and the limits to binary logic scaling", Nanotechnology, Vol. 17, No. 16, (2006), 4240, doi: 10.1088/0957-4484/18/29/298001.
  10. Ahmad, F. and Bhat, G., "Novel code converters based on quantum-dot cellular automata (QCA)", International Journal of Science and Research, Vol. 3, No. 5, (2014), doi.
  11. Kong, K., Shang, Y. and Lu, R., "An optimized majority logic synthesis methodology for quantum-dot cellular automata", IEEE Transactions on Nanotechnology, Vol. 9, No. 2, (2009), 170-183, doi: 10.1109/TNANO.2009.2028609.
  12. Wang, W., Walus, K. and Jullien, G.A., "Quantum-dot cellular automata adders", in 2003 Third IEEE Conference on Nanotechnology, 2003. IEEE-NANO 2003., IEEE. Vol. 1, (2003), 461-464.
  13. Tougaw, P.D. and Lent, C.S., "Logical devices implemented using quantum cellular automata", Journal of Applied Physics, Vol. 75, No. 3, (1994), 1818-1825, doi: 10.1063/1.356375.
  14. Abutaleb, M., "Robust and efficient quantum-dot cellular automata synchronous counters", Microelectronics Journal, Vol. 61, (2017), 6-14, doi: 10.1016/j.mejo.2016.12.013.
  15. Vetteth, A., Walus, K., Dimitrov, V.S. and Jullien, G.A., "Quantum-dot cellular automata of flip-flops", ATIPS Laboratory, Vol. 2500, (2003), 1-5, doi.
  16. AlKaldy, E., Majeed, A.H., Zainal, M.S. and Nor, D.M., "Optimum multiplexer design in quantum-dot cellular automata", arXiv preprint arXiv:2002.00360, (2020), doi: 10.48550/arXiv.2002.00360.
  17. Asfestani, M.N. and Heikalabad, S.R., "A unique structure for the multiplexer in quantum-dot cellular automata to create a revolution in design of nanostructures", Physica B: Condensed Matter, Vol. 512, (2017), 91-99, doi: 10.1016/j.physb.2017.02.028.
  18. Ahmad, F., Mustafa, M., Wani, N.A. and Mir, F.A., "A novel idea of pseudo-code generator in quantum-dot cellular automata (QCA)", International Journal for Simulation and Multidisciplinary Design Optimization, Vol. 5, No., (2014), A04, doi: 10.1051/smdo/2013012.
  19. Yaqoob, S., Ahmed, S., Naz, S.F., Bashir, S. and Sharma, S., "Design of efficient n‐bit shift register using optimized d flip flop in quantum dot cellular automata technology", IET Quantum Communication, Vol. 2, No. 2, (2021), 32-41, doi: 10.1049/qtc2.12008.
  20. Roshan, M.G. and Gholami, M., "4-bit serial shift register with reset ability and 4-bit lfsr in qca technology using minimum number of cells and delay", Computers & Electrical Engineering, Vol. 78, (2019), 449-462, doi: 10.1016/j.compeleceng.2019.08.002.
  21. Hashemi, S. and Navi, K., "New robust qca d flip flop and memory structures", Microelectronics Journal, Vol. 43, No. 12, (2012), 929-940, doi: 10.1016/j.mejo.2012.10.007.
  22. Gholamnia Roshan, M. and Gholami, M., "Novel d latches and d flip-flops with set and reset ability in qca nanotechnology using minimum cells and area", International Journal of Theoretical Physics, Vol. 57, No. 10, (2018), 3223-3241, doi: 10.1007/s10773-018-3840-1.
  23. Shamsabadi, A.S., Ghahfarokhi, B.S., Zamanifar, K. and Movahedinia, N., "Applying inherent capabilities of quantum-dot cellular automata to design: D flip-flop case study", Journal of Systems Architecture, Vol. 55, No. 3, (2009), 180-187, doi: 10.1016/j.sysarc.2008.11.001.
  24. Srivastava, S., Asthana, A., Bhanja, S. and Sarkar, S., "Qcapro-an error-power estimation tool for qca circuit design", in 2011 IEEE international symposium of circuits and systems (ISCAS), IEEE. (2011), 2377-2380.