Figure 3-3. Exclusive OR gate timing diagram.
THE EXCLUSIVE NOR GATE
The exclusive NOR (X-NOR) gate is nothing more than an X-OR gate with an inverted output. It
produces a HIGH output when the inputs are either all HIGH or all LOW. The standard symbol and the
Truth Table are shown in figure 3-4. The operation function sign is with a vinculum over the entire
Figure 3-4. Exclusive NOR gate and Truth Table.
A timing diagram for the X-NOR gate is shown in figure 3-5. You can see that from T0 to T1, when
both inputs are LOW, the output is HIGH. The output goes LOW when the inputs are opposite; one
HIGH and the other LOW. At time T3, both inputs go HIGH causing the output to go HIGH.