A Logic Gate is an electronic circuit that performs a specific logic operation based on one or more binary inputs and produces a single binary output. Logic gates are the building blocks of digital electronics and are used in microprocessors, memory devices, and digital systems.
Each logic gate implements a Boolean function and operates with binary inputs, i.e., 0 (Low) and 1 (High). They form the basis of digital computation.
Types of Basic Logic Gates
There are 5 commonly used logic gates:
- AND Gate
- OR Gate
- NOT Gate
- NAND Gate
- NOR Gate
1. AND Gate
The AND Gate is a digital logic gate that outputs HIGH (1) only when all its inputs are HIGH (1). If any input is LOW (0), the output will be LOW (0). It performs a logical multiplication of the inputs.
Boolean Expression: A · B = Q
2. OR Gate
The OR Gate is a digital logic gate that outputs HIGH (1) when at least one input is HIGH (1). It performs logical addition.
Boolean Expression: A + B = Q
3. NOT Gate
The NOT Gate, also known as an Inverter, has only one input and one output. It outputs the inverse of the input. If input is 1, the output is 0, and vice versa.
Boolean Expression: Q = A̅
4. NAND Gate
The NAND Gate is a combination of the AND gate followed by a NOT gate. It outputs LOW only when all inputs are HIGH. It is one of the universal gates, meaning you can implement any logic function using only NAND gates.
Boolean Expression: Q = (A · B)̅
5. NOR Gate
The NOR Gate is a combination of the OR gate followed by a NOT gate. It outputs HIGH only when all inputs are LOW. It is also a universal gate.
Boolean Expression: Q = (A + B)̅
Conclusion
Logic gates are the foundation of modern digital electronics. Understanding the behavior of AND, OR, NOT, NAND, and NOR gates helps in designing complex circuits such as multiplexers, adders, and digital processors.