Logic Gates
A logic gate is simply an electronic circuit which takes one or more electronic signals as input to give an output signal.
Basic Gates
NOT Gate
- It is an inverter circuit which has only one input signal and one output signal.
- It gives the complement of the input as the output.
- Symbol:
AND Gate
- It can have two or more input signals, but only one output signal.
- If any of the input is 0, output is 0.
- If all the inputs are 1, then the output is 1.
- Symbol:
OR Gate
- It can have two or more input signals, but only one output signal.
- If any of the input is 1, output is 1.
- If all the inputs are 0, then the output is 0.
- Symbol:
Universal Gates
NOR Gate
- It can have two or more input signals, but only one output signal.
- It is an inverted OR gate.
- If any of the input is 1, output is 0.
- If all the inputs are 0, then the output is 1.
- Symbol:
NAND Gate
- It can have two or more input signals, but only one output signal.
- It is an inverted AND gate.
- If any of the input is 0, output is 1.
- If all the inputs are 1, then the output is 0.
- Symbol:
Special Gates
XOR Gate
- The XOR( Exclusive OR ) gate can have two or more input signals, but only one output signal.
- If the input has an odd number of 1’s, output is 1 otherwise the output is 0.
- Its algebraic symbol is ⊕
- Symbol:
Q = A ⊕ B = (A’.B + A.B’)
XNOR Gate
- The XOR( Exclusive NOR ) gate can have two or more input signals, but only one output signal.
- If the input has an even number of 1’s, output is 1 otherwise the output is 0.
- Its algebraic symbol is ⊙
- Symbol:
Y = A ⊙ B = (AB)’ + AB