# Blog

## Why is it called ripple carry adder? ## How to construct 4-bit ripple carry adder VHDL code?

• The 4-bit Ripple Carry Adder VHDL Code can be Easily Constructed by Port Mapping 4 Full Adder. The following figure represent the 4-bit ripple carry adder. In the above figure, A, B 4-bit input, C0 is Carry in and S 4-bit output , C4 is Carry out. The remaining C1, C2, C3 are intermediate Carry. They are called signals in VHDL Code.

## What is carry adder and carry look ahead adder?

• Ripple carry adder and carry look ahead adder are two different kinds of digital binary adders based on the carry determining technique. Both adders can add the numbers without any problem. We will briefly discuss both adders in this article.

## How to add two 4-bit binary numbers using 4x ripple carry adder?

• 4-bit ripple carry adder is used for the purpose of adding two 4-bit binary numbers. In Mathematics, any two 4-bit binary numbers A 3 A 2 A 1 A 0 and B 3 B 2 B 1 B 0 are added as shown below- Using ripple carry adder, this addition is carried out as shown by the following logic diagram-  