Question

3. Answer the following questions about the flip-flop (F/F).

1) Explain the trigger of F/F.

2) Express the edge trigger condition around clock pulse (CLK).

(D F/F block diagram).

3) Fill out the characteristic table and excitation table for JK F/F and T F/F.

Answer 1

3.
1) When the state of a flip flop is changed by a small change in the input signal is called a trigger. This small change in input can either be clock pulses or an output from a flip flop or output from a circuit, etc. This change in output caused due to the before mentioned factors are applied as input to the flip flop, the output changes to the next state, this is when we say that the flip flop has been triggered.

2) When a flip flop is triggered in the moment when the clock pulses either goes from 0 to 1 (low to high) or from 1 to 0 (high to low), the flip flop is said to be edge triggered flip flop.
There are two types of edges, when the clock pulse goes from 0 to 1, it is called positive edge on the other hand when it goes from 1 to 0, it is called negative edge. When the flip flop gets triggered in either of the cases, it is said to be positive edge triggered and negative edge triggered flip flops respectively.



In a D flip flop, it is denoted as shown in the block diagram:

3) Characteristic table of JK flip flop

Excitation table of JK Flip flip

Characteristic table of T flip flop

Excitation table of T flip flop

In the tables shown in the above images Qn and Qn+1 are nothing but present and next stages repectively.