# N-Bit Parallel Subtractor

## N-Bit Parallel Subtractor

The subtraction can be carried out by taking the 1’s or 2’s complement of the number to be subtracted. For example we can perform the subtraction (A-B) by adding either 1’s or 2’s complement of B to A. That means we can use a binary adder to perform the binary subtraction.

### 4 Bit Parallel Subtractor

The number to be subtracted (B) is first passed through inverters to obtain its 1’s complement. The 4-bit adder then adds A and 2’s complement of B to produce the subtraction. S_{3} S_{2} S_{1} S_{0} represent the result of binary subtraction (A-B) and carry output C_{out} represents the polarity of the result. If A > B then Cout =0 and the result of binary form (A-B) then C_{out} = 1 and the result is in the 2’s complement form.