# Electrical – JK flip-flop timing diagram positive edge triggering

flipfloptiming-analysis

Welcome I would like to ask you for explain this timing diagrams. I got some assignments for reading timing diagrams and solved it but I am not sure if it is good.

I have JK flip-flop which is positive edge triggering (from low to high). Here is task

If I am not wrong the input is only J and K = 0 right?

Here is my solution

Guys, what do you think about it? Is it good?

Firstly, you should not see if it is a 'good' or 'bad' output, it should seem 'correct'.

This is how I see your question: It seems the INPUT port is your 'J' port, which is being given the signal; and you are expected to come out with the output value for the given change in J.

Because it is positive edge triggered, the output value will change only at the positive edge transition with respect to its output value in the previous clock cycle. I'll consider the following JK-flip flop truth table.

Let's analyze it for each clock edge.

CLK edge 1: The output was initially zero (or to be precise, high impedance) and at edge1, INPUT = J = 0. So, the output should be zero in this clock cycle.

CLK edge 2: The output in the previous cycle was zero and INPUT= 0 at edge2. Again, the output in this cycle is zero.

CLK edge 3:
The output in the previous cycle was zero and INPUT =1 at edge3. For J=1, the output is 1, for both K=0 or 1.

CLK edge 4: The output in the previous cycle was one and INPUT= 1 at edge4. For J=1, the output will toggle to 0 if K=1, or it will remain at 1 if K=0.

CLK edge 5: The output in the previous cycle could be 1 or 0, depending on the value of K. If output was 1, similar case of CLK edge 4 applies. If output was 0, for INPUT = J = 1, the output becomes 1, for both K=0 or 1.

I think that cleared enough. I have assumed K is not connected to any control input, hence the output values depend on it in certain clock edges. If the question was supposed to mean that INPUT is given to both J and K simultaneously, then choose the case accordingly. Let me know if you have any confusion.