Master Slave JK Flip Flop

Race Around Condition in JK Flip flop

When both J and K input of a JK Flip flop is set to 1, the output of the JK flip-flop will toggle between 1 and 0, which make the output of the flip-flop unstable. This is called the race-around condition in a JK Flipflop. to avoid this problem, we use the concept of a master-slave JK flip flop.

Design of Master Slave JK Flip flop

A Master-Slave JK Flip-Flop is designed by connecting two JK flip-flops in a series configuration. In these one flip-flop act as the master and the other as a slave. The output of the master flip-flop is connected to both the inputs of the slave flip-flop. Also, the outputs of the slave flip-flop are fed back to inputs of the master flip-flop. Block diagram of a master-slave JK flipflop is shown in the figure.

master slave jk flip flop

The circuit also includes an inverter and is connected. It passes the inverted clock pulse to the slave flip-flop. If the clock pulse is set to 0 for the master, then the clock pulse will become 1 for the slave and if Clk=1 for the master flipflop, it will become 0 for the slave flipflop. The circuit diagram of a master-slave Jk Flip flop is given below.

Master Slave JK FlipFlop circuit Diagram

Working of Master Slave JK Flip flop

The slave flip-flop is isolated until the Clk goes to 0. When the Clk goes to 0, values are passed from the master flip-flop to the slave and output is obtained.

If J=0 and K=1, \overline Q output of the master becomes 1 which is then transferred to the K input of the slave and the clock forces the slave to RESET, thus the slave flip-flop copies the master flip-flop.

If J=1 and K=0, Q output of the master becomes 1 and goes to the J input of the slave and the clock sets the slave, copying the master.

If both J=1 and K=1, the master toggles on the positive transition of the clock and the slave toggles on the negative transition of the clock.

If J=0 and K=0, Q remains unchanged.

Timing Diagram of Master Slave JK Flip flop

master slave jk flip flop timing diagram

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