Full Adder and its Inputs

A full adder is a combinational logic circuit that performs the addition of three bits. The three input bits of a full adder are A, B, and C (where C is the carry bit from the previous addition). The circuit adds the three bits and produces two outputs: Sum and Carry.

Sum Output of a Full Adder

The Sum output of a full adder is the result of adding the three input bits. The sum is calculated using the XOR (exclusive OR) gate. The XOR gate produces a 1 output when the inputs are different, and a 0 output when the inputs are the same. Therefore, the sum output of a full adder is given by:

Sum = A XOR B XOR C

Explanation:

- When A and B are different, the XOR gate produces a 1 output.
- If C is 1, then the XOR gate produces a 0 output because the carry bit is already included in the previous addition.
- If C is 0, then the XOR gate produces a 1 output because there is no carry bit to include in the addition.
- When A and B are the same, the XOR gate produces a 0 output.
- If C is 1, then the XOR gate produces a 1 output because the carry bit needs to be included in the addition.
- If C is 0, then the XOR gate produces a 0 output because there is no carry bit to include in the addition.

Therefore, the sum output of a full adder is given by A XOR B XOR C.

Conclusion

In conclusion, the sum output of a full adder is calculated using the XOR gate. The XOR gate produces a 1 output when the inputs are different, and a 0 output when the inputs are the same. Therefore, the sum output of a full adder is given by A XOR B XOR C.