  Quantum-dot cellular automata (QCA) is a likely candidate for future low
power nano-scale electronic devices. Sequential circuits in QCA attract more
attention due to its numerous application in digital industry. On the other
hand, configurable devices provide low device cost and efficient utilization of
device area. Since the fundamental building block of any sequential logic
circuit is flip flop, hence constructing configurable, multi-purpose QCA
flip-flops are one of the prime importance of current research. This work
proposes a design of configurable flip-flop (CFF) which is the first of its
kind in QCA domain. The proposed flip-flop can be configured to D, T and JK
flip-flop by configuring its control inputs. In addition, to make more
efficient configurable flip-flop, a clock pulse generator (CPG) is designed
which can trigger all types of edges (falling, rising and dual) of a clock. The
same CFF design is used to realize an edge configurable (dual/rising/falling)
flip- flop with the help of CPG. The biggest advantage of using edge
configurable (dual/rising/falling) flip-flop is that it can be used in 9
different ways using the same single circuit. All the proposed designs are
verified using QCADesigner simulator.
