Using Universal Nand-nor-inverter Gate to Design D-latch and D Flip-flop in Quantum-dot Cellular Automata Nanotechnology

The process of reducing dimensions in CMOS technology and also making digital devices more portable, faces serious challenges such as increasing frequency and reducing power consumption. For this reason, scientists are looking for a solution such as replacing CMOS technology with other technologies including Quantum-dot Cellular Automata (QCA) technology and many researches have designed digital circuits by using QCA technology. Flip-flops are one of the main blocks in most digital circuits. In this paper, a D-type flip-flop (D-FF) is presented in QCA technology that a majority gate has been used in its feedback path to reset. The D-FF is designed by the proposed D Latch which is based on Nand-Nor-Inverter (NNI) and a new inverter gate that the proposed D latch has ۲۴ cells and ۰.۵ clock cycle latency and ۰.۰۲ 〖μm〗^۲ area. The new inverter gate of the D-FF has output signal with high polarization level and lower area than previous inverters and the NNI gate of the D-FF is a universal gate. One of the applications of D-FFs with reset pin is the use in Phase-frequency detector (PFD). In the proposed scheme, a reset feature has been added to D-FF since the PFD structure can be designed. All of the proposed schemes are evaluated by the QCADesigner software and energy consumption simulations are estimated using QCAPro software for all proposed circuits.

Keywords:

Quantum-dot Cellular Automata , QCA , flip-flop , latch , PFD