Parallel Subtracter

A parallel subtracter is a digital circuit that can find the arithmetic difference of two binary numbers whose length size is greater than one bit, it does so by operating on corresponding bits in parallel. 

Working of a parallel subtracter:

1. A parallel subtracter is formed by a combination of full adders with a subtrahend complement input. 
2. It considers that the subtraction is equal to the addition of minuend along with the 2’s complement of the subtrahend. 
3. The 1s complement of B is obtained by the NOT Gate and the 2s complement is found by adding the carry. 
4. The process is repeated till the last full adder FAn uses the carry bit Cn to add with its input An and 2’s complement of Bn to generate the last bit of the output along with the last carry bit Cout. 

Reference

Parallel Subtracter