Universal college of engineering &

technology

.By Harsh Patel)130460111012

What is Adder?

Adder : In electronics an

adder is digital circuit that perform addition of numbers.In modern computer adder reside in the arithmetic logic unit (ALU).

Adders :Adders are important

not only in the computer but also in many types of digital systems in which the numeric data are processed.

Types of adder:

1. Half adder2. Full adder

Half adder :The half adder

accepts two binary digits on its inputs and produce two binary digits outputs, a sum bit and a carry bit.

Carrycoutinput

input Sum

Full adder :The full adder

accepts two inputs bits and an input carry and generates a sum output and an output carry.

input

input

A Sum

Carry

B

Cout Cin

input

Truth Table of AdderA B Cin Cout ∑

0 0 0 0 0

0 0 1 0 1

0 1 0 0 1

0 1 1 1 0

1 0 0 0 1

1 0 1 1 0

1 1 0 1 0

1 1 1 1 1

A

B

Cin

∑

Cout

Cout= (A B). Cin + A.B

Circuit of Adder

4-Bit Adder A single full –adder is capable of

adding two 1-bit numbers and input carry.

What happens if we want to add binary numbers with more than 1-bit?

The concept of additional full-adders must be used i.e. to add 2-bit numbers two adders must be needed and to add 4-bit numbers four adders must be needed.

4-Bit Adder

Thanks!