Class notes ECO3101 (ECO3130),

URK23CS8015
23.11.2023 FULL ADDER AFRIN BANU.S


FULL ADDER
It is a combinational logic circuit that can add two binary digits (bits) and a carry bit, and produces
a sum bit and a carry bit as output is known as a full-adder.
In other words, a combinational circuit which is designed to add three binary digits and produces two
outputs (sum and carry) is known as a full adder. Thus, a full adder circuit adds three binary digits,
where two are the inputs and one is the carry forwarded from the previous addition.
BLOCK DIAGRAM:




CIRCUIT DIAGRAM:




Logical Expression:
SUM = A’ B’ C-IN + A’ B C-IN’ + A B’ C-IN’ + A B C-IN = C-IN (A’ B’ + A B) + C-IN’ (A’ B + A B’) = C-IN XOR (A XOR B) = (1,2,4,7)
C-OUT = A’ B C-IN + A B’ C-IN + A B C-IN’ + A B C-IN = A B + B C-IN + A C-IN = (3,5,6,7)



K-MAP:




Advantages of Full Adder
● Full adder provides facility to add the carry from the previous stage.
● The power consumed by the full adder is relatively less as compared to half adder.
Applications of Full Adder
● Full adders are used in ALUs (arithmetic logic units) of CPUs of computers.
● Full adders are used in calculators.
● Full adders are used to generate memory addresses.