. These are elementary building blocks of digital circuit.
. Made by transistors.
. It has one or more inputs and only one output.
. Output is active only for certain input combinations.
. Common logic gates are:
- AND gate
- OR gate
- NAND gate
- NOR gate
Applications of Logic gates:
. Used as building blocks in every digital product.
. Used in multiplexers, Arithmetic and Logic Unit, Computer memory and Registers.
. Also found in mobiles, calculators, tablets and digital watches etc.
1. AND gate
. It has two inputs and one output.
. Output is active only when both the inputs are active.
. It can be observed in many home appliances.
. Example: Washing Machine works only when both power supply and Power ON button turned on.
Water flows into bucket only when wall on tank and water tap is open.
. It can be observed in many home appliances.
. Example: Washing Machine works only when both power supply and Power ON button turned on.
Water flows into bucket only when wall on tank and water tap is open.
. Symbol and Truth table of AND gate:
2. OR gate
. It has two inputs and one output.
. Output is active when either of inputs is active.
. Example: We can operate TV channels either from remote or buttons on TV.
Entering into home from either of doors opened.
. Example: We can operate TV channels either from remote or buttons on TV.
Entering into home from either of doors opened.
. Symbol and Truth table of OR gate:
3. NAND gate
. It has two inputs and one output.
. Works in the opposite function of AND gate.
. NAND and NOR gates are called Universal gates because we can achieve any other logic gate function using these two.
. NAND and NOR gates are called Universal gates because we can achieve any other logic gate function using these two.
. Output is inactive only when both the inputs are active.
. Symbol and Truth table of NAND gate:
4. NOR gate
. It has two inputs and one output.
. Works in the opposite function of OR gate
. Output is active only when both the inputs are inactive.