What is Half Adder?
Half adder is a combinational circuit that is used to add two 1-bit inputs to generate two outputs sum and carry. The sum in half adder is given by XORing both the inputs. The carry in the half adder is given by the product of both inputs. Half Adders are used in the Various Digital Systems Where Addition of Binary Numbers is Required Such as Arithmetic Circuits, Digital Calculators, Microcontrollers and Processors, Communication systems and Control Systems.
Expression for Sum in Half Adder
From the above truth table, the expression for sum S in half adder is:
S = A ⊕ B
where,
A and B are inputs and ⊕ represents XOR operation
Expression for Carry in Half Adder
From the above truth table, the expression for carry C in half adder is:
C = AB
Logic Diagram for Half Adder
To implement half adder, we require one XOR gate and one AND gate. Below is the logic diagram for half adder.
Half Adder
Block Diagram for Half Adder
Below is the block diagram for half adder.
Block Diagram of half Adder
Implementation of Full Adder Using Half Adders
Implementation of full adder from half adders is possible because the half adders add two 1-bit inputs in full adder we add three 1-bit inputs. To obtain a full adder from a half adder we take the first two inputs and add them and use the sum and carry outputs and the third input to get the final sum and carry output of the full adder. In this article, we will explore half adders, and full adders and implement full adders using half adders.
Table of Content
- What is Half Adder?
- What is Full Adder?
- Implementation
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