Logic Gates
Logic gates are the basic elements that make up a
digital system. The electronic gate is a circuit that is able to operate
on a number of binary inputs in order to perform a particular logical
function. The types of gates available are the NOT, AND, OR, NAND, NOR,
exclusive-OR, and the exclusive-NOR .
The gate is a digital circuit with one or more input
voltages but only one output voltage. The operation of a logic gate can
be easily understood with the help of Truth Table. A truth table is a
table that shows all the input-output possibilities of a logic circuit.
Logical Operators:
There are three basic logical operators: NOT/INVERT, AND and OR.
Logic Gates:
AND Gate
OR Gate
NAND Gate
NOR Gate
Exclusive-OR Gate
Exclusive-NOR Gate
NOT Gate:
The inverter performs a basic logic function called
inversion or complementation. The inverter changes one logic level to
its opposite level. when a HIGH level is applied to an inverter input, a
LOW level appear on its output. When LOW level is applied to it input, a
HIGH level appear on its output.
Symbol: Truth Table:
The AND Gate may have two or more inputs and a single
output .The opetaions of the AND gate is such that the output is
HIGH only when all of the inputs are HIGH. When any of the inputs are
LOW, the output is LOW.
Symbol: Truth Table:
OR Gate:
The OR Gate has two or more inputs ans one output.
The operations of the OR gate is to determine when one or more of its
inputs are HIGH and to produce a HIGH on its output toindicate this
condition.
Symbol: Truth Table:
NAND Gate:
The term NAND is a contraction of NOT-AND and implies
and AND function with a complemented (inverted) output. The NAND gate
is a universal gate as it can be used to construct an AND gate, an
OR gate an inverter or any combination of these functions. The logical
operation of the NAND gate is such that a LOW output occurs only when
all inputs are HIGH. When any of the inputs is LOW, the output will be
HIGH.
Symbol: Truth Table:
NOR Gate:
The term NOR Gate is the contraction of NOT-OR gate
is a universal gate. The logic operation of the NOR gate is that a LOW
output occurs when any if its inputs is high. Only when all of its
inputs are LOW, the output is HIGH.
Symbol: Truth Table:
The Ex-OR gate is an abbreviation for Exclusive-OR
gate. An Ex-OR gate has two or more inputs and one output. The Logic
operation of the Ex-OR gate is the output is HIGH only when the odd number of its input.
Symbol: Truth Table:
Exclusive-NOR Gate:
The EX-NOR gate is the contraction of
NOR-Exclusive-OR gate.An Ex-Nor gate has two or more inputs and has only
one output. The logic operation of the EX-NOR gate is the output is
HIGH only when the even number of its inputs or inputs having all
zeros.
Symbol: Truth Table:
See also:
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