Data comparison is needed in digital systems while performing arithmetic or logical operations. This comparison determines whether one number is greater than, equal, or less than the other number. A digital comparator is widely used in combinational system and is specially designed to compare the relative magnitudes of binary numbers.
These are also available in IC form with different bit comparing configurations such as 4-bit, 8-bit, etc. More than one comparator can also be connected in cascade arrangement to perform comparison of numbers of longer lengths.Whenever we want to compare the two binary numbers, first we have to compare the most significant bits.
If these MSBs are equal, then only we need to compare the next significant bits. But if the MSBs are not equal, then it would be clear that either A is greater than or less than B and the process of comparison ceases.
4-Bit Comparator:
It can be used to compare two four-bit words. The two 4-bit numbers are A = A3 A2 A1 A0 and B3 B2 B1 B0 where A3 and B3 are the most significant bits.
It compares each of these bits in one number with bits in that of other number and produces one of the following outputs as A = B, A < B>B. The output logic statements of this converter are
If A3 = 1 and B3 = 0, then A is greater than B (A>B). Or
If A3 and B3 are equal, and if A2 = 1 and B2 = 0, then A > B. Or
If A3 and B3 are equal & A2 and B2 are equal, and if A1 = 1, and B1 = 0, then A>B. Or
If A3 and B3 are equal, A2 and B2 are equal and A1 and B1 are equal, and if A0 = 1 and B0 = 0, then A > B.
These are also available in IC form with different bit comparing configurations such as 4-bit, 8-bit, etc. More than one comparator can also be connected in cascade arrangement to perform comparison of numbers of longer lengths.Whenever we want to compare the two binary numbers, first we have to compare the most significant bits.
If these MSBs are equal, then only we need to compare the next significant bits. But if the MSBs are not equal, then it would be clear that either A is greater than or less than B and the process of comparison ceases.
4-Bit Comparator:
It can be used to compare two four-bit words. The two 4-bit numbers are A = A3 A2 A1 A0 and B3 B2 B1 B0 where A3 and B3 are the most significant bits.
It compares each of these bits in one number with bits in that of other number and produces one of the following outputs as A = B, A < B>B. The output logic statements of this converter are
If A3 = 1 and B3 = 0, then A is greater than B (A>B). Or
If A3 and B3 are equal, and if A2 = 1 and B2 = 0, then A > B. Or
If A3 and B3 are equal & A2 and B2 are equal, and if A1 = 1, and B1 = 0, then A>B. Or
If A3 and B3 are equal, A2 and B2 are equal and A1 and B1 are equal, and if A0 = 1 and B0 = 0, then A > B.
