The EXCLUSIVE-OR gate

This is a gate where the output is high only if one or other inputs is high but not both. The Boolean algebra equation for such a circuit is:

Output = A.B' + A'.B
You should see that this of NOT and AND gates shown in Figure 1.


The NAND gate version of this Figure 2. is therefore simply two sets followed by an OR gate, as

The EXCLUSIVE-NOR gate

This gate gives a high output when its two inputs are equal, that is, both 0 or both 1. It is therefore known as the parity or equivalence gate.

This circuit may be realised with two NOT gates, two AND gates and an OR gate, as shown in Figure 3.