n bit parallel adder - mbits-mirafra/digitalDesignCourse GitHub Wiki

What is n-bit parallel adder?

An n-bit parallel adder is a digital circuit that adds two n-bit binary numbers in parallel.
The circuit performs the addition operation bit by bit, and it produces a sum output and a carry output for each bit.
The n-bit parallel adder consists of n full-adder circuits, where each full-adder circuit takes three inputs (A,B,cin to add) and produces two outputs (the sum and cout bit).
These full-adder circuits are connected in a way that allows the addition of the n-bit binary numbers to be performed in parallel.

                  n-bit parallel adder

Speed: An n-bit parallel adder is much faster than a serial adder, as it can process all of the bits of the numbers being added simultaneously. This makes it a crucial building block for applications that require high-speed arithmetic operations, such as computer processors, digital signal processors, and communication systems.
Simplicity: The circuitry of an n-bit parallel adder is relatively simple, consisting of a series of full adders that can be implemented using basic logic gates. This simplicity makes it easier to design and implement, as well as more cost-effective.

4- bit Parallel Adder is designed using 4 Full Adders FA A, FA B, FA C, FA D.
Full Adder FA A adds A0, B0 along with carry Cin to generate Sum S0 and Carry bit C1 and this Carry bit is connected to FA B.
FA A accepts this Carry C1 and adds with its inputs A1 and B1 to generate Sum S1 and Carry C2.
bit C2 is connected to FA B. This process continues till last Full Adder FA D.
FA D accepts the carry bit C3 and adds with its input A4 and B4 to generate S4 along with the last carry bit Cout.
c4 act as MSB bit for the sum
Finally sum = 0 1 1 1 0 which is noting but 14 in decimal where MSB bit c4 = 0

4- bit Parallel Adder is designed using 4 Full Adders FA A, FA B, FA C, FA D.
Full Adder FA A adds A0, B0 along with carry Cin to generate Sum S0 and Carry bit C1 and this Carry bit is connected to FA B.
FA A accepts this Carry C1 and adds with its inputs A1 and B1 to generate Sum S1 and Carry C2.
bit C2 is connected to FA B. This process continues till last Full Adder FA D.
FA D accepts the carry bit C3 and adds with its input A4 and B4 to generate S4 along with the last carry bit Cout.
c4 act as MSB bit for the sum
Finally sum = 1 0 0 0 1 which is noting but 17 in decimal where MSB bit c4 = 1

Arithmetic operations: Parallel adders are commonly used in arithmetic operations in digital circuits and microprocessors, such as in ALUs (Arithmetic Logic Units) or math co-processors.
Cryptography: Parallel adders can be used in cryptographic applications, such as in encryption and decryption algorithms. They can perform binary addition of two n-bit binary numbers as part of the encryption or decryption process.
n-bit parallel adders are used in a variety of real-time applications where fast addition of binary numbers is required. These applications include microprocessors, digital signal processing, cryptography, and control systems.

Low power consumption: The use of parallel adders can result in lower power consumption compared to sequential adders that require multiple clock cycles to perform binary addition of n-bit binary numbers.
Ease of implementation: Parallel adders are relatively easy to implement using digital circuits and microprocessors.

Area: The area required to implement an n-bit parallel adder increases with the number of bits, making it challenging to implement in certain applications with limited space or where area is a critical factor.
Delay: The propagation delay of the carry signal in an n-bit parallel adder can become a significant factor as the number of bits increases. This can result in slower operation and increased power consumption.
Complexity: The design and implementation of n-bit parallel adders can be more complex compared to sequential adders, particularly when using more advanced architectures such as carry-lookahead or carry-select adders.