Adders in digital Electronics Notes. A combinational logic circuit that performs the addition of three single bits is called Full Adder. Full Adder Circuit Using Logic Gates A and B which add two input digits and generates a carry and a sum. . A binary adder is something which deals with addition of binary numbers. Carry Skip Adder CSkA Carry Increment Adder CIA Carry Look Ahead Adder CLA Carry Save Adder CSA Carry Select Adder CSlA and Carry Bypass Adder CBA are discussed below. There are two inputs and two outputs in a Half Adder. 8-bit and 16-bit Carry Look-ahead Adder circuits can be designed by cascading the 4-bit adder circuit. Half adder Full adder. The half adder circuit has two inputs. In the full adder the first carry C is always zero when the first add operation starts. There are basically two types of adders. Inputs are named as A and B and the outputs are named as Sum S and Carry C. ...