Scan flip-flop, scan chain circuit including the same, and control method of the scan flip-flop

A scan flip-flop comprising:

• a multiplexer configured to provide an internal signal through an input switch;
• a first latch circuit configured to latch the internal signal, wherein the first latch circuit comprises a first inverter, a second inverter, a first switch connected in parallel with the first inverter, and a second switch connected in series with the second inverter, wherein one terminal of the first switch, one terminal of the second switch, and an input terminal of the first inverter are connected to each other, and another terminal of the first switch, an output terminal of the first inverter, and an input terminal of the second inverter are connected to each other;
• a second latch circuit configured to latch an output of the first latch circuit and output a latched value, wherein the second latch circuit comprises a third inverter, a fourth inverter, an output inverter connected in series with the third inverter, and a fourth switch connected in series with the fourth inverter, wherein one terminal of the fourth switch and an input terminal of the third inverter are connected to each other, and an output terminal of the third inverter, an input terminal of the fourth inverter, and an input terminal of the output inverter are connected to each other;
• and
• a third switch configured to switch between the first latch circuit and the second latch circuit.