Q. Illustrate Characteristic tables of flip-flops?

Excitation Tables

Characteristic tables of flip-flops present the subsequent state when inputs and present state are known. These tables are helpful for analysis of sequential circuits. However at the time of design process we know the needed transition from present state to subsequent state and wish to find necessary flip-flop inputs. Hence comes need of a table which lists needed input values for given change of state. This kind of table is known as excitation Table. Fig presents excitation tables for all flip-flops.

Figure:  Excitation Tables for flip-flops

Q(t) & Q(t+1) denotes present and subsequent state for a flip flop respectively. Symbol X in table means don't care condition which implies it doesn't matter whether input is 0 or 1.