## The easy way to understand What is Logic Gate.

If you are interested in electronics, then you need to know about What is logic gates because everything in electronics is made up of logic gates. Integrated circuits (ICs) are built of logic gates. You will get much information about logic gates on books and the internet but in this post, you will learn basic of logic gate which is more important.

At first, we will learn actually what a Logic Gate is. Logic Gates is the digital electronics circuit. We already have known that every electrical and electronic circuit have input and output. Similarly, logic gates have input and output. Now a question is arise why it is called a digital circuit. Logic gates are called digital circuit because here the signal (input or output) must be one of two discrete levels. Each level is interpreted as one of two different states (example ON/OFF or High/Low).

You can call Logic Gates as an electronic switch. Now an important question is that how Logic gates are made or what inside a logic gate. Logic Gates are primarily implemented using diodes or transistors, but can also be constructed using vacuum tubes, electromagnetic relays even mechanical elements. In modern practice, most gates are made from Field Effect Transistors, particularly MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

Inside the logic gate, the input signals are processed using transistor configurations that implement the desired logic function. The transistor configuration can vary depending on the specific logic gate type. For example, an AND gate would use transistors in series, while an OR gate would use transistors in parallel.

Based on the input signals and the internal circuitry, the logic gate produces an output signal. The output signal is also a binary value, either 0 or 1. It is typically represented by a voltage level, where a LOW output is near 0 volts, and a HIGH output is near the supply voltage (Vdd).

Also, remember that, the transistor configurations and voltage thresholds within the logic gate determine how the input signals are processed to generate the output. For example, in CMOS (Complementary Metal-Oxide-Semiconductor) logic gates, a threshold voltage is set to differentiate between a LOW and HIGH input or output.

There are many devices like Multiplexer, Registers, ALU, Flip-Flops are made of "Logic gates".
Logic Gates are available in form of IC. Like  IC7400, IC7408, IC7404 etc.

Here are the most commonly used logic gates,

AND Gate: The AND gate has two or more inputs and produces a HIGH output only when all of its inputs are HIGH. The output is LOW even if any one of the inputs is LOW.

OR Gate: The OR gate also has two or more inputs and produces a HIGH output if any of its inputs are HIGH. The output is LOW only if all of the inputs are LOW.

NOT Gate (Inverter): The NOT gate has only one input and produces the logical complement of that input. If the input is HIGH, the output is LOW, and vice versa.

XOR Gate (Exclusive OR): The XOR gate has two inputs and produces a HIGH output if the number of HIGH inputs is odd. It produces a LOW output if the number of HIGH inputs is even.

NAND Gate (NOT-AND): The NAND gate is the combination of AND gate and NOT gate. It produces a LOW output only when all of its inputs are HIGH. For any other input combination, it produces a HIGH output.

NOR Gate (NOT-OR): The NOR gate is the combination of OR gate and NOT gate. It produces a HIGH output only when all of its inputs are LOW. For any other input combination, it produces a LOW output.

XNOR Gate (Exclusive NOR): The XNOR gate is the combination of XOR gate and NOT gate. It produces a HIGH output if the number of HIGH inputs is even. It produces a LOW output if the number of HIGH inputs is odd.

Easy way to understand What is Logic Gate. Reviewed by Author on October 14, 2018 Rating: 5