LOGIC

GATES
 LOGIC GATES
Is device that acts as a building block
of digital circuits. They perform basic
logical functions that are fundamental
to digital circuits.
In a circuit, logic gates will make
decisions based on a combination of
digital signals coming from its input.
 THE SEVEN BASIC LOGIC
GATES
 AND Gate
 OR Gate (or inverter)
 NOT Gate
 XOR Gate (Exclusive-OR Gate)
 NAND Gate
 NOR Gate
 XNOR Gate (Exclusive-NOR Gate)
1. AND
GATE
The “AND” gate is so named because, if 0 is called
“false” and 1 is called “true”, the gate acts in the
same way as the logical “and” operator. The output
is TRUE when both inputs are TRUE. Otherwise, the
output is FALSE. In other words, the output is 1 only
when both inputs one “AND” two are 1.
Input 1 Input 2 Output
0 0 0
0 1 0
1 0 0
1 1 1
AND GATE
2. OR
GATE
The OR gate gets its name from fact that it
behaves after the fashion of the logical inclusive
“or”. The outputs is TRUE if either or both inputs
are TRUE. If both inputs are FALSE, then the output
is FALSE. In other words, for the output to be 1, at
least input one OR two must be 1.
Input 1 Input 2 Output
0 0 0
0 1 1
1 0 1
1 1 1
OR GATE
3. XOR GATE
The XOR (exclusive-OR) gate acts in the
same way as the logical “either/or”. The
output is TRUE if either, but not both, of the
inputs are TRUE. The output is FALSE if both
inputs are FALSE or if both inputs are TRUE.
Input 1 Input 2 Output
0 0 0
0 1 1
1 0 1
1 1 0
XOR GATE
4. NOT OR INVERTER GATE
A logical inverter, sometimes called NOT gate to
differentiate it from other types of electronic
inverter devices, has only one input. It reverses
the logic state. If the input is 1, then the output
is 0. if the input is 0, then the output is 1.

INPUT OUTPUT
1 0
0 1
NOT GATE
5. NAND GATE
The NAND gate operates as an AND gate
followed by a NOT gate. It acts in the manner
of the logical operation “AND” followed by
negation. The output is FALSE if both inputs
are TRUE. Otherwise, the output is TRUE.
Input 1 Input 2 Output
0 0 1
0 1 1
1 0 1
1 1 0
NAND GATE
6. NOR GATE
The NOR gate is a combination OR gate
followed by an inverter. Its output is
TRUE if the both inputs are FALSE.
Otherwise, the output is FALSE.
Input 1 Input 2 Output
0 0 1
0 1 0
1 0 0
1 1 0
NOR GATE
7. XNOR GATE
The XNOR (exclusive-NOR) gate is a
combination of XOR gate followed by an
inverter. Its output is TRUE if the inputs
are the same, and false if the inputs are
different.
Input 1 Input 2 Output
0 0 1
0 1 0
1 0 0
1 1 1
XNOR GATE
USES OF GATESOF GATES
 Use for doorbell
 Use in smoke sensors
 Use in traffic lights
 Use in mobile or calculators
 Use in UPS chips
 INTEGRATED CIRCUITS
Bite-sized circuit which is composed
of THOUSANDS or MILLIONS of
capacitors, diodes, resistors,
transistors and conductive pathways
They are more popularly called as
“MICROCHIP” or “CHIP”.
1. NAND
2. NOR
3. XNOR
4. AND
5. NOT
6. OR
7. XOR
 ADVANTAGES OF USING
IC’S
1. COMPACTNESS
- ICs REDUCE OVERALL SIZE
OF AN ELECTRONIC DEVICE
SINCE THEY ARE VERY SMALL
 ADVANTAGES OF USING
IC’S
2. COST EFFICIENT
- ICs IN APPLIANCES AND
OTHER DEVICES LOWERS
MAINTENACE COST.
 ADVANTAGES OF USING
IC’S
3. ENERGY EFFICIENT
- ICs ARE EXTREMLY SMALL
AND REQUIRES LESS POWER
THAN EQUIVALENT DISCRETE
COMPONENT CIRCUITS.
LIMITATION OF IC
TECHNOLOGY
IC CANNOT ACCOMMODATE VERY LARGE
CURRENT OR VOLTAGES.
HEAT GENERATED IN SMALL SPACE CAUSE
AN INCREASE IN TEMPERATURE BEYOND
LIMIT OF THE DEVICE.
CANNOT IMPLEMENTED IN ELECTRICAL
DEVICES SUCH AS INDUCTORS,
TRANSFORMERS AND LARGE CAPACITORS.