A full adder combinational circuit hasa)3 inputs and 2 outputsb)2 inpu...
The basic block diagram for a Full Adder is as shown:
A Full adder can be realized using two half adders as shown:
We, therefore, conclude that a full adder combinational circuit has 3 inputs and 2 outputs.
A full adder can be implemented using 2 XOR, 2 AND, 1 OR as shown in figure:
Important PointThe truth table of a full adder logic is:

S = A ⊕ B ⊕ C
The Sum output bit of a full adder is given by:
The carry output bit of a full adder is given by:
X1 = AB + BC + AC
A full adder combinational circuit hasa)3 inputs and 2 outputsb)2 inpu...
Understanding Full Adder Circuits
A full adder is a crucial component in digital electronics, used for binary addition. Let's break down its characteristics:
Inputs of a Full Adder
- A full adder requires three inputs:
- Two inputs represent the bits to be added (let's call them A and B).
- One input is the carry-in (C_in) from a previous less significant bit addition.
Outputs of a Full Adder
- The full adder produces two outputs:
- The sum output (S) results from the addition of the input bits and the carry-in.
- The carry-out (C_out) indicates if there is a carry that needs to be added to the next more significant bit.
Functionality of a Full Adder
- The full adder operates based on the following logic:
- The sum (S) can be calculated as: S = A XOR B XOR C_in.
- The carry-out (C_out) can be calculated as: C_out = (A AND B) OR (C_in AND (A XOR B)).
Conclusion
In summary, a full adder indeed has three inputs and two outputs. It plays a vital role in arithmetic operations within digital circuits, especially in constructing arithmetic logic units (ALUs) and adding circuits. Option 'A' is correct as it accurately reflects the input-output configuration of a full adder.