M R. K E R I N S

Logic Gates- Electrical Engineering

LOGIC GATES

• Logic gates are primarily implemented using diodes or transistors acting as electronic switches, but can also be constructed using electromagnetic relays (relay logic), fluidic logic, pneumatic logic, optics, molecules, or even mechanical elements.

LOGIC GATES

• Digital systems are said to be constructed by using logic gates. • Examples: • AND, OR, NOT,

NAND, NOR, EXOR and EXNOR gates.

TRUTH TABLES

• A truth table shows how a logic circuit's output responds to various combinations of the inputs, using logic 1 for true and logic 0 for false. All permutations of the inputs are listed on the left, and the output of the circuit is listed on the right.

TYPES OF LOGIC GATES

AND LOGIC GATES

• A HIGH output (1) results only if both the inputs to the AND gate are HIGH (1). If neither or only one input to the AND gate is HIGH, a LOW output results.

AND LOGIC GATES

OR LOGIC GATES

• A HIGH output (1) results if one or both the inputs to the gate are HIGH (1). If neither input is HIGH, a LOW output (0) results

INPUTA B

OUTPUTA + B

0 0 00 1 11 0 11 1 1

OR GATES

NOT LOGIC GATE

• The NOT gate is an electronic circuit that produces an inverted version of the input at its output. It is also known as an inverter. If the input variable is A, the inverted output is known as NOT A. This is also shown as A', or A with a bar over the top.

NOT LOGIC GATE

NOT LOGIC GATES

NAND LOGIC GATES

• This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate. The outputs of all NAND gates are high if any of the inputs are low. The symbol is an AND gate with a small circle on the output. The small circle represents inversion.

NAND LOGIC GATES

IC CHIP WITH LOGIC GATE EXAMPLE

LOGIC GATES

•Logic gate video tutorial

• Quiz – Logic Gates • 5 questions only