Full adder

The full adder or a cascade of full adders can be used to add multi-digit binary numbers.

The full adder has the label FA and has three inputs and two outputs. The two inputs A and B represent the bits to be added. With the input CI (carry in), a previous carry can be included in the addition.

The output S (sum) represents the last digit of the sum and the output CO (carry out) represents the carry.

The circuit diagram TP1012_08_3_1.circ shows a 4-bit full adder.

Truth table

A B CI S CO
0 0 0 0 0
0 1 0 1 0
1 0 0 1 0
1 1 0 0 1
0 0 1 1 0
0 1 1 0 1
1 0 1 0 1
1 1 1 1 1

Adjustable parameters

Input
Designation Range Default value
Voltage level (lo) 0.1 ... 24 V 0.8
Voltage level (hi) 0.1 ... 24 V 2
Output
Designation Range Default value
Voltage level (lo) 0 ... 24 V 0
Voltage level (hi) 0.1 ... 24 V 5
Resistance 0.1 ... 1000 Ohm 50

See also