Exclusive OR gate (XOR gate)

Shihab Uddin Ahmed | March 12, 2017

Exclusive OR gate is also known as EOR gate or EXOR gate. This logic gate may have two or more inputs and XOR gates always have one output.

Its logic is as simple as previously discussed logic gates. Just think the meaning of the word ‘exclusive’; XOR gate output logic is true (high) when only one of its inputs are true. Please see the truth table below:

Truth table for two input XOR gate photo

Truth table for two input XOR gate

From the truth table above we can notice that output is low even when both inputs are high. For high state in XOR gate output we need exclusive state, which means only one input have to be at high state for high output. From the truth table above there is another interesting point to note, XOR gate output is same as one bit binary addition, hence XOR gate can be used in adder circuit.

Two input XOR gate symbol photo

Two input XOR gate symbol

IEEE XOR symbol photo

IEEE XOR symbol

For three or more inputs

For three or more inputs in XOR gate the principle is, output will be high for odd number of high states in inputs.

Truth table for three input XOR gate photo

Truth table for three input XOR gate

Boolean expression for XOR gate:

Boolean expression for XOR gate photo

XOR gate IC

7486 is a XOR gate IC where four gates are included in a single IC.

XOR gate IC photo

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