JK Flip-Flop

JK Flip-Flop

A storage element with two control inputs, J and K, defined by the input relation: D = JQ’ + K’Q

D = JQ’ + K’Q

The Boolean equation of the JK flip flop

JK Flip Flop’s Characteristic Behavior

• J = 0, K = 0 → Hold State (Q(t+1) = Q(t))

• J = 1, K = 0 → Set (Q = 1)

• J = 0, K = 1 → Reset (Q = 0)

• J = 1, K = 1 → Toggle

J input

The input inside the JK flip-flop that behaves like the S (Set) input.

K input

The input inside the JK flip-flop that behaves like the R (Reset) input.

Unlike SR, the case of J = K = 1 is valid in the JK flip-flop.

Advantage of the JK flip-flop over the SR flip-flop

When J = K = 1, the JK flip-flop toggles like a T flip-flop

The relationship between the JK flip-flop and T flip-flop

SR flip-flop

Unlike the SR latch, it has a controlled timing, it is synchronous, it’s edge based. However, just like the SR latch, it suffers from the invalid case when S = R = 1.

Versatility of a JK flip-flop

Can be used as:

• SR flip-flop (when J and K act like Set/Reset)

• T flip-flop (when J = K)

• General-purpose storage like D flip-flop