*. We are starting a new tutorial that is a full piece of information about a logic Circuit. The circuit that we are learning today is Full Adder. In our previous tutorial, we have seen 2-Bit Full Adder using Logic Gates in Proteus software today we are going to design & simulate 4-Bit Full Adder using Logic Gates in Proteus. We will discuss following topics in today's lecture:*

**The Engineering Projects**- What are the Adders?
- How can we define Full Adder and its types?
- What is the working mechanism of Four bits Full Adder ?
- What is the Procedure to simulate four bit full Adder in Proteus ISIS?
- What is the example of the Solving the addition process?

## Adders

In Computer system, computation is an important procedure. The adders play a vital role in this Process. First of all, Let's define the Adders:In the world of electronics, adders are used to add the bits. The computer system depends upon the flow of bits and the computation of bits. Adders take the input in the form of bits and perform the addition according to the type of Adder used. Basically, we divide the adders into"TheAddersare the Logical Circuits that are specially designed to add the two or more numbers in a system."

**two**types:

- Half Adder.
- Full Adder.

"we further classify the Full Adder into two main types:Full Addersare the Circuits that have a ability to to add two inputs bit along with a carry bit, hence it contain a carry input,twobits inputs andtwo outputsfor the result and the resultant carry."

- Two bits Full Adder.
- Four bits Full Adder.

## 4-bit Full Adder

As the name implies, a four bit full adder can add four input bits. The definition of Four bits Full adder is given next:"AThe Circuit of Four bit Full Adder consists of the XOR Gate, AND Gate and OR Gate. We have Learnt about them in detail. Lets have a quick recap of these Gates.four bitfull Adders is a Logical Circuit that takes Carry and two expressions withfour bitsas its inputs and as a result shows theFour bitsoutput along with thecarryat output terminals."

### XOR Gate

A XOR Gate, is a two input Logical Circuit that give the output HIGH only when the inputs have the values alternating of each other. Or else, it is LOW.### AND Gate

**AND**

**Gate**is the a logical Circuit that gives the Output HIGH only when its both inputs are

**HIGH**, otherwise the output is LOW.

### OR Gate

The OR Gate is a logical Circuit with the working such that when on of the Input is**HIGH**, the value of the Output is also

**HIGH**.

## DID YOU KNOW????????????????

You can make the Full Adder by simply merging two Half Adders in a specialized manner.

## Working Mechanism of 4-bit Full Adders

The Four bit Full Adders works in interesting manner. The XOR Gates are responsible for the addition of input bits. In order to get the full addition circuit we attach two AND gates with the circuit in such a way that the result of addition connects the OR Gate and we get the carry. In the designing of circuit, we simply make a small circuit of AND Gate and XOR Gate. Then we design a Circuit of**two**

**bits Full Adder**. The cynosure of the circuit is, we'll copy the block and arrange four blocks in a way that the output carry of the block becomes the input carry of the next. This cycle will continue and at the fourth block we get the resultant carry of whole calculation. we can input only one carry of our will at the Block A.

## Practical performance of 4-Bit Full Adder

If you wish to stimulate the Four bits full adder in Proteus then follow the simple steps given below. We'll make our circuit according to the Functional Diagram given before.- Begin Your Proteus Software.
- Get the required material.

### Required Devices

- XOR Gate
- AND Gate
- OR Gate
- Logic Toggle
- LED
- Ground Terminal

- Push the "P" button presented at left area of the screen.
- Select first four elements from the Library by mere writing there names one after the other.
- Get a XOR Gate and one AND Gate.
- Connect the Logic Toggles with each input of XOR Gate.
- Connect an LED with the end of the XOR Gate.
- Go to Terminal Mode and get the ground terminal to attach the Ground Terminal with LED.
- Drag and drop two XOR Gates, two AND Gates and one OR Gate and arrange them at the working area one after the other according to the image given below:
- Attach Logic Toggle with each input of switch 1.
- Get the LED and join it with the output of switch 3.
- Click the left button of mouse> go to Terminals> Ground Terminal.
- Place the ground Terminal just below the LED.
- Join all the components according to the images given below;

- Select the whole block left click>drag and drop the required area. It will create a doted square around the circuit.
- Right Click> copy block.
- Right click the mouse and paste the block with the same procedure.

- Repeat the Pasting Process one time more and paste the circuit copy just one below the other.
- Connect the each output carry switch with the input of the next.
- Grab the Logic Toggle from the Pick Library and join it with the input carry wire of the first block.

- Change the input values by the mean of Logic Toggles and check the working.

## Working Example of 4-bit Full Adder in Proteus

You can test the circuit with an example.**Question**: We have two numbers

**1100**and

**1010**. Find the resultant through four bits Full Adder. Answer: Let A=1100 B=1010

### Logic about For bit Full Adder

The 1st Logic Toggle of each XOR 1 switch is called A bit. The 2nd Logic Toggle of each XOR 1 represents the B bit. Turning of LED means the HIGH (1) and vise versa. We start to input from down to up and the output as well. Hence start the observation from block D to A. For the Question, the circuit should be set as: Hence we got the answer that is:A | 1 | 1 | 0 | 0 |

B | 1 | 0 | 1 | 0 |

Result | (1 carry)0 | 1 | 1 | 0 |