This adder is tough to implement than a half-adder. the complete adder could be a very little tougher to implement than an adder. The distinction between a half-adder and a full-adder is that the full-adder has 3 inputs and 2 outputs, whereas adder has solely 2 inputs and 2 outputs. therefore we all know that Half-adder circuit features a major disadvantage that we have a tendency to don’t have the scope to produce ‘Carry in’ bit for addition. just in case of full adder construction, we will truly create a carry in input within the electronic equipment and will add it with different 2 inputs A and B.


              Fig: Full-Adder Symbol


The full-adder is sometimes apart during a cascade of adders, that add eight, 16, 32, etc. binary numbers. Thus, a full adder circuit may be enforced with the assistance of 2 adder circuits. the primary adder circuit is going to be accustomed add A and B to provide a partial total.

The second last half|half adder logic may be accustomed add CIN to the total made by the primary half adder circuit. you’ll be able to see that the output Sum is Associate in Nursing XOR between the input A and therefore the half-adder, total output with B and Cin inputs. we tend to take Cout can solely be true if any of the 2 inputs out of the 3 area unit HIGH.


Fig: Full Adder Diagram

The implementation of larger logic diagrams is feasible with the higher than full adder logic a less complicated image is generally accustomed to represent the operation. within the higher than the diagram, we tend to square measure adding 2 three-bit binary numbers. we square measure able to see 3 full adder circuits are cascaded along. Those 3 full adder circuits turn out the ultimate total result, that is created by those 3 total outputs from 3 separate adder circuits.
Here is that the advantage of the total adder circuit. we will cascade single bit full adder circuits and will add 2 multiple bit binary numbers. this sort of cascaded full adder circuit is named as Ripple Carry Adder circuit. this sort of circuit conjointly has limitations. it’ll turn out unwanted delay after we attempt to add massive numbers.



Fig: Full Adder Truth Table


We add 2 adder circuits with an additional addition of OR circuit and acquire an entire full adder circuit. As per arithmetic, if we tend to add 2 ranges we’d get full number, the identical factor is occurring here fully adder circuit construction.

once each inputs area unit low then add and perform are going to be logic LOW, if input is high then add is going to be logic HIGH and perform are going to be logic LOW, once 2 inputs area unit high then add becomes logic LOW and perform becomes logic HIGH once all inputs area unit HIGH the output add and perform are going to be logic HIGH. 2 input XOR circuit, two input, AND gate, 2 input OR circuit kind the complete adder logic circuit, Input & Output of this multidimensional language will be derived by the subsequent truth table.