Digital Electronics Series
XNOR Gate: Equality Logic
Working Principle, Truth Table & Digital Verification
Live XNOR Logic Simulator
Input A
Input B
Equality Y
1
Toggle the inputs: Output is HIGH only when A and B are the same!
The XNOR gate (Exclusive NOR) is a digital logic gate that serves as the logical complement of the XOR gate. It is essentially an Equality Detector—it outputs a HIGH signal if and only if all of its inputs are identical.
01 Truth Table
| Input A | Input B | Output Y |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
Boolean Expression
Y = \overline{A \oplus B}
Practical Applications
Equality Comparators
XNOR gates compare two binary numbers and output 1 if they match exactly.
Digital Verification
Used in Built-In Self-Test (BIST) hardware to verify expected output vs actual output.
Pattern Matching
Essential in search hardware to find specific bit sequences in a data stream.