Digital electronics form an integral part of the electronics system. Dealing with this digital data involves performing operations like addition, subtraction, and modulation on digital data. One such operation i.e. addition is performed on digital data using a full adder which will be discussed in this article.
We will discuss the full adder applications and the working Principle of full adder. Later we will discuss the advantages and disadvantages of full adder. The article will conclude with some insights on future trends of full adder. In case of any doubt, Readers are advised to go through the frequently asked questions.
What is a Full Adder?
Full adder is used for performing the addition operation on binary bits. A certain circuit needs to be built to perform this addition operation on numbers, primarily binary numbers. Let us see the formal definition of full adder.
The electronic circuit built for the addition of two or more numbers is known as a full adder. It is capable of producing a carry and a sum bit.
Truth Table
Here is the truth table of full adder given below :
Working Principle of Full Adder
The full adder is used to add the sum of two numbers A and B by storing the carry bit(C) and the sum in the sum bit(S) . S is the least significant bit of the sum.
Let us study the principle of full adder
A full adder takes two or more than two numbers to be added as the input. Note that these numbers to be added have two or more bits otherwise, they could be added using a half adder.
The LSBs(least significant bits) add up and can generate a carry stored in the carry bit of the full adder. This carry is shifted to the next significant column and added to the two bits of that column.
The sum bit therefore stores the sum of the current two bits and the carry generated from the previous calculation is stored in the carry bit.
Applications of Full Adder
Let us study some applications of full adder
Used in CPUs
Full adders form an integral part of CPUs where it is used for arithmetic and logical operations. Computers often have to perform certain standard operations on Data done by the ALU unit of the CPU. The machine-level language is a combination of 0s and 1s so full adders can be used in the ALU unit for mathematical operations.
Used in Calculators
Similar to calculations performed in CPU, the calculators are also designated with the task of performing calculations like addition, subtraction, multiplication, and other scientific operations depending on the type of calculator. Out of these operations, a full adder is used for performing the addition of numbers. This is how full adders installed in the calculator help in performing the calculations.
Used in Multiplexers
Anybody who has worked with multiplexers will have the idea that multiplexers can be used for representing signals and then realizing them through logical circuits. Often these circuits are a combination of many different circuits that need to be added together to obtain the final circuit. Adders are therefore used in Multiplexers to realize the circuits and represent them for different uses.
Used in GPU
Applications that deal with Graphics generally require a lot of computation to deal with designs. Graphical designers make the use of GPUs(graphical processing units) to design these Graphics. The GPU is capable of performing complex computations due to the electrical circuits present in it. The major part of GPU I.e. the ALU(arithmetic and logical unit) performs this computation and has a full adder as one of its components. This adder circuit can perform calculations and give accurate results.
Used to generate memory points
Generation of memory addresses requires the use of full adders that are capable of Generating the sum and carry of numbers. These addresses can be used for storing data in a certain memory. The adders can perform another task of Generating program counterpoint. This is necessary when implementing different instructions that require you to move the pointer from one location to another.
Advantages of Full Adder
Let us study some advantages of full adder
- Full adder has the ability to store the carry generated in the previous step and add it to the current output.
- The Power Consumption of full adder circuits is less than that of half adder circuits making it a more common choice.
- The computations performed in a full adder are faster as compared to the time taken for the computations performed in a half adder circuit.
- Full adder circuit used in a large number of appliances like circuits that make up the multiplexers and ALUs in CPUs.
- Conversion of full adder circuit to half subtractor or half adder circuit is very easy whereas the other way round is a bit difficult.
Disadvantages of Full Adder
let us study some disadvantages of full adder.
- Multiple Full adders can be used for the implementation of circuits. As the number of full adders increase, the complexity of the circuit increases. Realization of such circuits is difficult.
- With an increase in number of full adders, propagation delay is introduced in the circuit. The stages later in the cascade have to wait until the previous input reaches them.
- For each bit in the number fed as the input, the computation power of the circuit increases therefore large power consumption can make these adders less efficient.
- Full adders are designed for performing addition operations on binary numbers. In order to perform arithmetic addition, extra circuitry is needed which further increases the complexity of the circuit.
- The power consumption per bit results in heat generation. This heat generated can be problematic for circuits that are designed for professional use.
Future Trends
With the advancement in technology, it is believed that full adder circuits will develop. This development can be seen in terms of compactness in the size of the full adder circuit leading to small sized full adders that won't occupy much space. Some other advancements can be an improved computation speed which reduces the time taken by full adder to perform computations. This will reduce the propagation delay and make adders advanced. Many ideas can come up that can help to improve the structure or efficiency of full adders.
Conclusion
We have seen that full adder is an important device that finds its application in various fields ranging from education to research. Its ability to perform accurate additions makes it a common installation in circuits used for solving large computations. More improvements can be made in the logic gate implementation by using parallel procession. With further advancements, full adder can be used in many more applications.