What is meant by 'edge triggered'? Differentiate SR-FF and JK-FF with their functional operation and excitation tables.

Edge Triggered:

In digital electronics, an edge-triggered flip-flop (FF) is a type of flip-flop that changes state only on the rising or falling edge of the clock signal. This means that the output of the flip-flop is not affected by the level of the clock signal, but only by its transition. This behavior is in contrast to level-triggered flip-flops, which change state when the clock signal is at a specific level (high or low).

Edge-triggered flip-flops are used in a variety of digital circuits, including registers, counters, and state machines. They are often preferred over level-triggered flip-flops because they are less susceptible to noise and are easier to design.

SR-FF (Set-Reset Flip-Flop):

The SR-FF is a basic edge-triggered flip-flop with two inputs, S (Set) and R (Reset), and two outputs, Q and Q'. The functional operation of the SR-FF is as follows:

• When the S input is high and the R input is low, the Q output is set to high and the Q' output is set to low.
• When the S input is low and the R input is high, the Q output is set to low and the Q' output is set to high.
• When both the S and R inputs are low, the state of the flip-flop does not change.
• When both the S and R inputs are high, the flip-flop is said to be in an undefined state.

The excitation table for the SR-FF is as follows:

S	R	Q	Q'
0	0	Q	Q'
1	0	1	0
0	1	0	1
1	1	X	X

JK-FF (J-K Flip-Flop):

The JK-FF is an edge-triggered flip-flop with two inputs, J (Set) and K (Reset), and two outputs, Q and Q'. The functional operation of the JK-FF is as follows:

• When the J input is high and the K input is low, the Q output is set to high and the Q' output is set to low.
• When the J input is low and the K input is high, the Q output is set to low and the Q' output is set to high.
• When both the J and K inputs are low, the state of the flip-flop does not change.
• When both the J and K inputs are high, the Q output toggles (changes from high to low or low to high) and the Q' output also toggles.

The excitation table for the JK-FF is as follows:

J	K	Q	Q'
0	0	Q	Q'
1	0	1	0
0	1	0	1
1	1	Q'	Q

Differences between SR-FF and JK-FF:

• The SR-FF has two inputs, S and R, while the JK-FF has two inputs, J and K.
• The SR-FF has an undefined state when both the S and R inputs are high, while the JK-FF toggles its output when both the J and K inputs are high.
• The JK-FF is more versatile than the SR-FF because it can be used to implement both S-R and T (Toggle) flip-flops.