XNOR Truth Table

Input		Output
A	B
0	0	1
0	1	0
1	0	0
1	1	1

The XNOR gate (sometimes spelled "exnor" or "enor") is a digital logic gate

Logic gate

A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...

 whose function is the inverse of the exclusive OR (XOR

XOR gate

The XOR gate is a digital logic gate that implements an exclusive or; that is, a true output results if one, and only one, of the inputs to the gate is true . If both inputs are false or both are true , a false output results. Its behavior is summarized in the truth table shown on the right...

) gate. The two-input version implements logical equality

Logical equality

Logical equality is a logical operator that corresponds to equality in Boolean algebra and to the logical biconditional in propositional calculus...

, behaving according to the truth table to the right. A HIGH output (1) results if both of the inputs to the gate are the same. If one but not both inputs are HIGH (1), a LOW output (0) results.

Symbols

There are two symbols for XNOR gates: the 'professional' symbol and the 'rectangular' symbol. For more information see Logic Gate Symbols.

The XNOR gate with inputs A and B implements the logical expression .

Hardware description and pinout

XNOR Gates are basic logic gates, and as such they are recognised in TTL

Transistor-transistor logic

Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...

 and CMOS

CMOS

Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

 IC

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

s. The standard, 4000 series

4000 series

The 4000 series is a family of industry standard integrated circuits which implement a variety of logic functions using Complementary Metal–Oxide–Semiconductor technology, and are still in use today. They were introduced by RCA as CD4000 COS/MOS series in 1968, as a lower power and more versatile...

, CMOS IC is the 4077 or the 74266, which includes four independent, two-input, XNOR gates. The pinout diagram is as follows:

1 Input A1 2 Input B1 3 Output Q1 4 Output Q2 5 Input B2 6 Input A2 7 Vss 8 Input A3 9 Input B3 10 Output Q3 11 Output Q4 12 Input B4 13 Input A4 14 Vdd

This device is available from most semiconductor manufacturers such as NXP. It is usually available in both through-hole DIP

Dual in-line package

In microelectronics, a dual in-line package is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board or inserted in a socket.A DIP is usually referred to as a DIPn, where n is...

 and SOIC

Small-Outline Integrated Circuit

A small-outline integrated circuit is a surface-mounted integrated circuit package which occupies an area about 30–50% less than an equivalent DIP, with a typical thickness that is 70% less. They are generally available in the same pinouts as their counterpart DIP ICs...

 format. Datasheets are readily available in most datasheet databases. DIL

Dual in-line package

In microelectronics, a dual in-line package is an electronic device package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board or inserted in a socket.A DIP is usually referred to as a DIPn, where n is...

 is a Dual In Line package, and SIL

Single in-line package

A single in-line package is an electronic device package which has one row of connecting pins. It is not as popular as the dual in-line package which contain two rows of pins, but has been used for packaging RAM chips and multiple resistors with a common pin. SIPs group RAM chips together on a...

 is a Single In Line package.

Alternatives

If no specific XNOR gates are available, one can be made from four NOR gates or five NAND gates in the configurations shown below. In fact, any logic gate can be made from combinations of only NAND gates

NAND logic

NAND gates are one of the two basic logic gates from which any other logic gates can be built. Due to this property, NAND and NOR gates are sometimes called "universal gates". However, modern integrated circuits are not constructed exclusively from a single type of gate...

 or only NOR gates

NOR logic

Like NAND gates, NOR gates are so-called "universal gates" that can be combined to form any other kind of logic gate. For example, the first embedded system, Apollo Guidance Computer, was built exclusively from NOR gates, about 5,600 in total for the later versions. Today, integrated circuits are...

.

See also

• Kronecker delta function
• Logical biconditional
  Logical biconditional
  In logic and mathematics, the logical biconditional is the logical connective of two statements asserting "p if and only if q", where q is a hypothesis and p is a conclusion...