This document discusses half adders and full adders used in digital circuits. A half adder accepts two binary digits as input and produces a sum and carry bit as output using one XOR and one AND gate. A full adder accepts three inputs - two bits to be added and a carry in bit - and produces a sum and carry out bit using two half adders and an OR gate. The main difference between them is that a full adder can add three bits while a half adder can only add two bits.

1. Moeez Ahmad
1421-316267

2. Adder
 In an electronic circuit that preforms addition
of numbers. In modern computer adder
resides in Arithmetic logic Unit(ALU).
 Types of Adder:
Half Adder
Full Adder

3. Half Adder
 The half adder accepts two binary digits on its
inputs and produces two binary digits output,
a sum bit and carry bit.
 Half Adder is formed with one Exclusive OR
gate and one AND gate.

5. Block Diagram of Half Adder
HALF ADDER
SUM(S)
Carry(C)
A
B

6. Half Adder Logic Circuit
B
A
SUM(S)
Carry(C)

7. Half Adder Truth Table
A B SUM Carry
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1

8. Full Adder
 The full adder accepts two input bits and an
input carry and generates a sum output and
an output carry.
 We can implement full adder circuit with the
help of two half adder circuit.

9. 2 INPUT OR GATE:

10. Block Diagram of Full Adder
FULL ADDER
SUM(S)
Cout
A
B
Cin

11. Full Adder Logic Circuit
B
A
Cin
SUM(S)
Cout

12. Full Adder Truth Table
A B Cin SUM Cout
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

13. What is main difference between Half
and Full adder?
 Main difference is that Full adder receives
three inputs and half adder receives two
inputs.
 Full Adder is formed by combination of two
half Adders.