Service manual

STP 11-25R13-SM-TG
Q - 25
Figure Q-20. XOR Gate
(1) Looking at the truth table, you can derive a Boolean expression for the XOR gate:
_ _
AB + AB = C
(2) The gates required to perform these expressions can now be established. Figure Q-21 shows
the XOR construction. This configuration satisfies the definition of an XOR gate.
Figure Q-21. XOR Gate
h. Exclusive NOR (XNOR)
. A XNOR is the complement of the XOR gate. By inverting the outputs
of the XOR, the circuit is changed into an XNOR. The Boolean expression and truth table are listed in
Table Q-15.
Table Q-15. XNOR Boolean Expression and Truth Table
_ _
AB + AB
_ _ _ _ _ _ _ _
AB + AB A A B B AB AB AB+AB
1 0 1 0 1 0 0 0
0 0 1 1 0 1 0 1
0 1 0 0 1 0 1 1
1 1 0 1 0 0 0 0