AND Gate Truth Table – Details, Symbol & Circuit Diagram


This article will teach about the AND Gate, its symbol, complex operation, AND Gate truth table, its timing diagram, multiple input AND logic Gate, and standard package IC 7408. So let’s start with the basic knowledge of AND gate.

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AND Logic Gate

  • AND Gate is one of the Basic logic gates that we are using in Digital Electronics.
  • AND is one of the logic operators. It performs the logical multiplication on its inputs.
  • The output is high (Y=1) if and only if all the inputs to the gate are high (1).
  • The output is low (0) if at least one of the inputs is low (0).
  • AND gate can have two or more inputs and only one output.

Symbol of AND Gate

  • The logical symbol of two inputs AND Gate is shown in the figure below. A and B are the inputs while Y is the output.
symbol of AND gate

Truth Table For AND Gate

  • The truth table of two inputs AND Gate is also shown in the figure.
  • Note that the output is HIGH only when both the inputs are HIGH.
Truth table for and gate

Boolean Expression of AND Gate

  • The expression relating the inputs and output of a logic gate is called the Boolean Expression.
  • The Boolean Expression of AND gate is,

\boxed{\mathbf{Y =\; A\cdot B }}

where the “dot” between A and B represents multiplication.

  • By substituting different values of A and B into the Boolean expression we can get the corresponding state of the output. This is how we can verify the truth table of the gate. 

Multiple Input AND gate and Truth Table

  • The symbol and truth table for the 3-input and 4-input AND gate are shown in the figure below.
multiple input AND gate

Boolean Expression for 3-input and 4-input AND Gate

  • The Boolean expression for a 3-input AND gate is:

\boxed{\mathbf{Y =\; A\cdot B \cdot C}}

  •  The Boolean expression for a 4-input AND gate is:

\boxed{\mathbf{Y =\; A\cdot B \cdot C \cdot D}}

Timing Diagram of AND Gate

  • The operating principle of an AND gate remains the same even for the pulsed inputs. This is evident from the figure shown below.
  • The input and output waveform for the pulsed operation is also shown in the figure.
timing diagram of AND gate

AND Gate IC 7408 Standard Package

  • The AND gate is available in the monolithic integrated circuit form.
  • IC7408 is a 14-pin TTL integrated circuit with four AND gates inside. It is therefore called Quad AND gate IC.
and gate ic 7408
  • The pin configuration of IC 7408 is shown above figure. Pin 14 is connected to the +5v supply and pin number 7 is connected to the ground.
  • The four AND gates inside IC 7408 are completely independent of each other.

Download Datasheet for IC 7408 PDF: IC 7408 Datasheet PDF

Frequently Asked Questions on AND Logic Gate

Answer: An AND gate is an electrical circuit that combines two signals so that the output is on if both signals are present. The output of the AND gate is connected to a base driver which is coupled to the bases of transistors, and alternately switches the transistors at opposite corners of the inverter.

Answer: The AND gate is used for data transmission control in digital electronics. AND gate allows or disallows the transmission of data through a channel.

Answer: The AND gate is a logic gate that gives an output of ‘1’ only when all of its inputs are ‘1’. Thus, its output is ‘0’ whenever at least one of its inputs is ‘0’. Mathematically, Q = A ยท B. The OR gate is a logic gate that gives an output of ‘0’ only when all of its inputs are ‘0’.

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