In jk Flip flop, the output is feedback to the input, and therefore change in the output causes the change in inputs. due to this in the postive half of the clock pulse if j and k both are high then the output toggles simultaneously. this condition is known as Race around condition.
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It will be more beneficial for the students if u explain JK filp flop before explaining this race around condition.
ReplyDeleteA JK flip-flop has two inputs similar to that of RS flip-flop. We can say JK flip-flop is a refinement of RS flip-flop. JK means Jack Kilby, a Texas instrument engineer who invented IC. The two inputs of JK Flip-flop is J (set) and K (reset). A JK flip-flop is nothing but a RS flip-flop along with two AND gates which are augmented to it.
ReplyDeleteThe flip-flop is constructed in such a way that the output Q is ANDed with K and CP. Such an arrangement is made so that the flip-flop is cleared during a clock pulse only if Q was previously 1. Similarly Q’ is ANDed with J and CP, so that the flip-flop is cleared during a clock pulse only if Q’ was previously 1.
When J=K=0
When both J and K are 0, the clock pulse has no effect on the output and the output of flip-flop is same as its previous value. This is because when both the J and K are 0, the output of their respective AND gate becomes 0.
When J=0, K=1
When J=0, the output of the AND gate corresponding to J becomes 0(i.e.) S=0 and R=1. Therefore Q’ becomes 0. This condition will reset the flip-flop. This represents the RESET state of Flip-flop.
When J=1, K=0
In this case, the AND gate corresponding to K becomes 0(i.e.) S=1 and R=0. Therefore Q becomes 0. This condition will set the Flip-flop. This represents the SET state of Flip-flop.
When J=K=1
Consider the condition when CP=1 and J=K=1. This condition will cause the output to complement again and again. This complement operation continues until the Clock pulse goes back to 0. Since this condition is undesirable, we have to find a way to eliminate this condition. This undesirable behaviour can be eliminated by Edge triggering of JK flip-flop or by using master slave JK Flip-flops.
It is always advisable to exlain with visuals
ReplyDeleteIt is always advisable to exlain with visuals
ReplyDelete