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XNOR gate

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An XNOR gate is a special part used in digital logic. It is also known by names like ENOR or EXNOR. Some people call it an equivalence gate. This name comes from how it works with two inputs. It checks if those two inputs are exactly the same. This gate is the opposite of an XOR gate.

XNOR ANSI Labelled
XNOR ANSI Labelled

How does this gate work? It looks at two signals, which we call inputs. If both inputs are high, the output is high. If both inputs are low, the output is also high. This happens because the inputs match. However, if one input is high and the other is low, the output is low.

3 gate XNOR
3 gate XNOR

The gate only gives a high output when the inputs are identical. This is why it is used to find equality.

Engineers can build these gates in many different ways. One way is to use an XOR gate and then add a NOT gate. You can also use a mix of AND, OR, and NOT gates. Some people use four NOR gates to make one XNOR gate. There are also ways to use only NAND gates.

XNOR from NAND
XNOR from NAND

Some designs are faster than others. Others use fewer parts to save space.

XNOR from NOR
XNOR from NOR

Many companies make these parts for computers. Texas Instruments and NXP are names of such manufacturers. You can find them in different formats like DIP or SOIC. The 4000 series CMOS chip called the 4077 is a common one. It contains four independent XNOR gates inside. Another chip is the 74266, which is a TTL version.

XNOR from NAND 2
XNOR from NAND 2

These gates are part of a much bigger system. They help machines follow rules to make decisions. While a two-input gate checks for equality, you can have more inputs too. For example, a three-input version might work differently. In that case, the output is high if an even number of inputs are high.

XNOR from NOR 2
XNOR from NOR 2

This helps us understand how complex computers can think through many steps.

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🖼️ Images & Media (6)
File:3 gate XNOR.svg
3 gate XNOR.svg
File:XNOR ANSI Labelled.svg
XNOR ANSI Labelled.svg
File:XNOR from NAND.svg
XNOR from NAND.svg
File:XNOR from NOR.svg
XNOR from NOR.svg
File:XNOR from NAND 2.svg
XNOR from NAND 2.svg
File:XNOR from NOR 2.svg
XNOR from NOR 2.svg
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