Logic Circuit

Digital Circuit Elements: Logic Gates A fundamental component of digital circuits, a logic gate serves as a foundational building block. Typically featuring two inputs and one output, each terminal exists in a binary state—either low (0) or high (1) at any given moment. The state of a terminal, and consequently the logic gate, may frequently […]

Digital Circuit Elements: Logic Gates

A fundamental component of digital circuits, a logic gate serves as a foundational building block. Typically featuring two inputs and one output, each terminal exists in a binary state—either low (0) or high (1) at any given moment. The state of a terminal, and consequently the logic gate, may frequently change as the circuit processes data. The logic gate processes input signals in a logical manner, generating an output value of ‘1’ for ON or ‘0’ for OFF based on the input conditions.

There are three primary types of logic gates: AND, OR, and NOT.

 

Binary Coding

Logic gates operate within a binary numbering system, referred to as binary code. This system, consisting solely of 1s and 0s, aligns with the language used by computers.

 

Inputs And Outputs

Logic gates typically have two or more inputs, except for the NOT gate, which has only one input. Regardless of the number of inputs, all gates produce only one output. Inputs and outputs are commonly labeled with letters such as A, B, C, etc.

 

LOGIC SYMBOL OF THE “AND” GATE

AND Gate

OPERATION OF THE AND GATE

The AND gate functions akin to having multiple switches in series. For the output to be ‘ON’ (1), all input switches must be closed (ON or set to 1). If any input is ‘OFF’ (0), the output remains ‘OFF’.

 

TRUTH TABLE FOR “AND” GATE

| INPUT | INPUT | OUTPUT |

|——-|——-|——–|

|   0   |   0   |   0    |

|   0   |   1   |   0    |

|   1   |   0   |   0    |

|   1   |   1   |   1    |

 

All inputs of the AND gate must be ‘1’ for the output to be ‘1’; otherwise, the output is ‘0’.

OR GATE

The OR gate operates like having multiple switches in parallel. Only one closed switch (ON or set to 1) is needed for the output to be ‘ON’ (1).

 

LOGIC SYMBOL FOR “OR” GATE

OR Gate

TRUTH TABLE FOR “OR” GATE

| INPUT | INPUT | OUTPUT |

|——-|——-|——–|

|   0   |   0   |   0    |

|   0   |   1   |   1    |

|   1   |   0   |   1    |

|   1   |   1   |   1    |

 

Applying ‘1’ to either or both inputs of the OR gate results in an output of ‘1’; ‘0’ on both inputs yields an output of ‘0’.

NOT GATE

The NOT gate possesses a single input and output, reversing the input signal value. If the input is ‘1’, the output is ‘0’, and if the input is ‘0’, the output is ‘1’.

 

LOGIC SYMBOL FOR “NOT” GATE

NOT Gate

TRUTH TABLE FOR “NOT” GATE

| INPUT | OUTPUT |

|——-|——–|

|   0   |   1    |

|   1   |   0    |

The NOT gate, also known as an inverter, consistently produces the opposite signal of its input.

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