Tag: Half Adder and Full Adder Tutorial

Full Adder | Definition | Circuit Diagram | Truth Table

Half Adder-

 

Before you go through this article, make sure that you have gone through the previous article on Half Adder.

 

We have discussed-

  • Half Adder is used for the purpose of adding two single bit numbers.
  • Half adders have no scope of adding the carry bit resulting from the addition of previous bits.
  • To overcome this drawback, full adder comes into play.

 

 

In this article, we will discuss about Full Adder.

 

Full Adder-

 

  • Full Adder is a combinational logic circuit.
  • It is used for the purpose of adding two single bit numbers with a carry.
  • Thus, full adder has the ability to perform the addition of three bits.
  • Full adder contains 3 inputs and 2 outputs (sum and carry) as shown-

 

 

Full Adder Designing-

 

Full adder is designed in the following steps-

 

Step-01:

 

Identify the input and output variables-

  • Input variables = A, B, Cin (either 0 or 1)
  • Output variables = S, Cout where S = Sum and Cout = Carry

 

Step-02:

 

Draw the truth table-

 

Inputs
Outputs
ABCinCout (Carry)S (Sum)
00000
00101
01001
01110
10001
10110
11010
11111

Truth Table

 

Step-03:

 

Draw K-maps using the above truth table and determine the simplified Boolean expressions-

 

 

Also Read- Full Subtractor

 

Step-04:

 

Draw the logic diagram.

The implementation of full adder using 1 XOR gate, 3 AND gates and 1 OR gate is as shown below-

 

 

To gain better understanding about Full Adder,

Watch this Video Lecture

 

Next Article- Half Subtractor

 

Get more notes and other study material of Digital Design.

Watch video lectures by visiting our YouTube channel LearnVidFun.

Half Adder | Definition | Circuit Diagram | Truth Table

Half Adder-

 

  • Half Adder is a combinational logic circuit.
  • It is used for the purpose of adding two single bit numbers.
  • It contains 2 inputs and 2 outputs (sum and carry).

 

 

Half Adder Designing-

 

Half adder is designed in the following steps-

 

Step-01:

 

Identify the input and output variables-

  • Input variables = A, B (either 0 or 1)
  • Output variables = S, C where S = Sum and C = Carry

 

Step-02:

 

Draw the truth table-

 

InputsOutputs
ABC (Carry)S (Sum)
0000
0101
1001
1110

Truth Table

 

Step-03:

 

Draw K-maps using the above truth table and determine the simplified Boolean expressions-

 

 

Also Read- Half Subtractor

 

Step-04:

 

Draw the logic diagram.

The implementation of half adder using 1 XOR gate and 1 AND gate is as shown below-

 

 

Limitation of Half Adder-

 

  • Half adders have no scope of adding the carry bit resulting from the addition of previous bits.
  • This is a major drawback of half adders.
  • This is because real time scenarios involve adding the multiple number of bits which can not be accomplished using half adders.

 

To overcome this drawback, Full Adder comes into play.

 

To gain better understanding about Half Adder,

Watch this Video Lecture

 

Next Article- Full Adder

 

Get more notes and other study material of Digital Design.

Watch video lectures by visiting our YouTube channel LearnVidFun.