What is Full Adder made of?

A full adder is a combinational logic circuit that performs the addition of three bits. It is composed of two half adders and an OR gate. The two half adders are used to add the two input bits, and the OR gate is used to add the carry bit from the previous stage.

The full adder circuit is shown in the figure below.

[Image of a full adder circuit]

The inputs to the full adder are A, B, and Cin, and the outputs are S and Cout. The output S is the sum of the three input bits, and the output Cout is the carry bit that is generated when the sum of the three input bits is greater than or equal to 2.

The full adder circuit works as follows. The two half adders are used to add the two input bits, A and B. The first half adder adds A and B, and the second half adder adds the carry bit from the previous stage, Cin, to the sum of A and B. The OR gate is used to add the carry bits from the two half adders. The output S is the sum of the three input bits, and the output Cout is the carry bit that is generated when the sum of the three input bits is greater than or equal to 2.

Full adders are used in a variety of digital circuits, including arithmetic logic units (ALUs), microprocessors, and microcontrollers.