Question

The waveforms below represent the inputs to a negative edge-triggered J-K flip-flop. At which point(s) willits Qoutput go HIGH? clock 5 : 1 : 3 : 4 a 2 point 3 points 1 and 4 points 1.3 and 4 D point 2

Options selected are not correct.

Answer 1

FOR FIRST QUESTION :

at point 3 (first option)

• The negative edge triggered FF changes it’s output only when the clock makes a transition fron high to low i.e at the negative edge (or falling) edge of the clock.
• TRUTH TABLE for negative edge-triggered j-k flip flop :

  

Inputs Outputs JK CLK Q & Comments 0 0 9. 2. No change 0 1 0 1 Reset 10 10 Set 11 O. Q. Toggle

• as we can see from truth table of the a negative edge-triggered j-k flip flop the Q output goes HIGH when input J is HIGH and inpit K is LOW at falling edge of clock. Only at point 3 input J is HIGH and K is LOW at falling edge of clock so output Q will be HIGH.

FOR SECOND QUESTION :

it will RESET (first option)

• The negative edge triggered FF changes it’s output only when the clock makes a transition fron high to low i.e at the negative edge (or falling) edge of the clock.
• TRUTH TABLE for negative edge-triggered j-k flip flop :

  

Inputs Outputs JK CLK Q & Comments 0 0 9. 2. No change 0 1 0 1 Reset 10 10 Set 11 O. Q. Toggle

• when input J is LOW and input K is HIGH at falling edge of the clock the output of the negative edge-triggered j-k flip flop is RESET.

FOR THIRD QUESTION :

the time that input must be stable before the clock transition (second option)

• setup time is defined as the minimum amount of time before the clock's active edge that the data must be stable for it to be latched correctly. This is so that the data can be stored successfully in the storage device.