Summary Logic gates chapter 1 notes

Logic Gates - Definition, Types
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Logic gates are the fundamental building blocks in digital electronics.
 Used to perform logical operations based on the inputs provided to it and
gives a logical output that can be either high(1) or low(0).
 The operation of logic gates is based on Boolean algebra, or
mathematics.
 There are basically seven main types of logic gates that are used to
perform various logical operations in digital systems.
 By combining different logic gates, complex operations are performed,
and circuits like flip-flops, counters, and processors are designed. In this
article, we will see various types of logic gates in detail.
 Logic gates find their uses in our day-to-day lives, such as in the
architecture of our telephones, laptops, tablets and memory devices.




Types of Logic Gates
Logic gates can be broadly classified into three main categories :
AND GATE
An AND gate is used to perform logical Multiplication of binary input. The Output
state of the AND gate will be high (1) if both the input is high (1), else the output
state will be low(0) if any of the input is low (0).
The Boolean Expression or logic for the AND gate is the logical multiplication of
inputs denoted by a full stop or single dot as :
A. B=X
The value of X will be True when both the inputs will be True.

,Two Input AND Gate
Properties of AND Gate
The following are two main properties of the AND gate:
1. AND gate can accept two or more than two input values at a time.
2. When all of the inputs are logic 1, the output of this gate is logic 1.
OR GATE
OR GATE is most widely used digital logic circuit. The output state of OR gate will
be high i.e., (1) if any of the input state is high or 1, else output state will be low i.e.,
0.
The Boolean Expression for the OR gate is the logical addition of inputs denoted
by plus sign (+) as
X= A+B
The value of X will be high(true) when one of the inputs is set to high (true).




Two Input OR Gate
Properties of OR Gate

, An OR gate have the following two properties:
1. It can have two or more input lines at a time.
2. When all of the inputs to the OR gate are low or logic 0, the output of it
is low or logic 0.
NOT GATE
In digital electronics, the NOT gate is one of the basic Logic Gate having only a
single input and a single output. It is also known as inverter or inverting buffer.
When the input signal is "low" the output signal is "high" and vice-versa.
The Boolean expression of NOT Gate is as follows
Y = Ā or
Y = A’
the value of Y will be high when A will be low.




NOT Gate
Properties of NOT Gate
 The output of a NOT gate is complemented or inverse of the input
applied to it.
 NOT gate takes only one output.
NOR GATE
The NOR gate is the type of universal logic gate. It takes two or more inputs and
gives only one output. The output state of the NOR gate will be high (1) when all
the inputs are low (0). NOR gate returns the complement result of the OR gate. It is
basically a combination of two basic logic gates i.e., OR gate and NOT gate.
The Boolean expression of NOR gate is as follows:
If A and B are considered as two inputs, and O as output, then the expression for a
two input NOR gate will be
O = (A + B)’
The value of O will be true when all of its inputs are set to 0.