A D flip-flop can be implemented using NAND logic gates by performing the following steps:

  1. Connect two NAND gates in a cross-coupled arrangement, with the output of each gate connected to the input of the other gate.
  2. Connect the D input to one of the NAND gates' inputs.
  3. Connect a clock input to both NAND gates' inputs, with the clock signal flipped by an inverter to one of the inputs.
  4. Connect an enable input to both NAND gates' inputs, with the enable signal flipped by an inverter to one of the inputs.

The resulting circuit will be a D flip-flop made up of NAND gates, and the output states will be as follows:

  • When Enable=0, the output of each NAND gate will be 1, and the flip-flop will retain its previous state.
  • When Enable=1 and Clock transitions from low to high, the input D is latched at the output Q of the flip-flop.
  • When Enable=1 and Clock transitions from high to low, the output Q of the flip-flop remains at the last latched D input.

The implemented D flip-flop using NAND gates can be used as a basic memory element in digital systems, such as data registers, timing generators, state machines, and other logic circuits.