Full Adder
What is a full adder?
Full adder is a combinational circuit that consists of two EX-OR Gates, two AND gates, and one OR gate.
It has three inputs and gives two outputs
The equation obtained is the sum of the binary digits and the output is the carry obtained by addition.
Truth Table
The truth table for full adder is as follows:
| Input | Output | |||
| A | B | Cin | Sum | Carry |
| 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 1 | 0 |
| 0 | 1 | 0 | 1 | 0 |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 | 0 |
| 1 | 0 | 1 | 0 | 1 |
| 1 | 1 | 0 | 0 | 1 |
| 1 | 1 | 1 | 1 | 1 |
Logical Expression:
SUM = (A XOR B) XOR Cin = (A ⊕ B) ⊕ Cin
CARRY-OUT = A AND B OR Cin(A XOR B) = A.B + Cin(A ⊕ B)
Reference