“To design & verify truth table of XOR & XNOR Gate”
“To design & verify truth table of XOR & XNOR Gate”
1. Objective:
The main objective is to design and verify the truth table of
i.
XOR Gate
ii.
XNOR Gate
2.
Components:
i.
Bread
Board
ii.
Connecting
Wires
iii.
LED
iv.
Battery
v.
3 IC’s
a. IC 7432 for OR Gate
b. IC 7408 for AND Gate
c. IC 7404 for NOT Gate
3. Introduction:
3.1.Bread Board:
A
bread board is an electronic board into which the electrical components like
diodes and resistors are placed. The sockets of bread board are sturdy and
rugged. Diodes or other electrical components should be placed without making
any damage to the board.
3.2.Logic Gates:
Logic gates
are the basic building blocks of any digital system. It is any electronic
system having one or more input and only one output. The relationship between
input and output is based on some logic. At any given moment every terminal is
at one of two binary conditions 0 or 1.
Following are
the logic gates which we are going to design in this experiment:
i.
XOR Gate
ii.
XNOR Gate
3.2.1.
XOR Gate:
XOR gate is a combination of OR AND and NOT 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." Another
way of looking at this circuit is to observe that the output is 1 if the inputs
are different, but 0 if the inputs are the same. The symbol of NOR gate
is shown below:
The truth table for XOR gate which we have observed is shown below:
A
|
B
|
Y
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
0
|
The truth
table of NOR gate indicates that the output signal is one only for the time
when both the inputs are 0.
3.2.2.
XNOR Gate:
XNOR is the combination of AND NOT & OR gate. The XNOR (exclusive-NOR)
gate is a combination XOR
gate followed by an inverter. Its output is "true"(1) if the inputs are the same, and" false"(0)
if the inputs are different.
The truth table for XNOR gate which we have observed is shown below:
A
|
B
|
Y
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
1
|
3.3.Integrated Circuits:
A circuit of transistors, resistors, and capacitors constructed on a single semiconductor wafer or chip, in which the components areinterconnected to perform a given function. IC’s consume very little current, generate comparatively
little heat, and are far more shock-proof and reliable than the older
discrete-component circuits.
An integrated circuit consists of a number of circuit components (e.g. transistors, diodes, resistors
etc.) and them inter connections in a single small package to perform a
complete electronic function. These components are formed and connected within
a small chip of semiconductor material. IC’s can be used as advanced logic
gates. Some IC’s description is given below which can be used for logic gates.
No.
|
Description
|
7400
|
Quad two-input NAND gate (four NAND
gates)
|
7402
|
Quad two-input NOR gate (four NOR
gates)
|
7404
|
Hex inverter (six NOT gates)
|
7408
|
Quad two-input AND gate (four AND
gates)
|
7432
|
Quad two-input OR gate (four OR
gates)
|
7486
|
Quad two-input XOR gate (four XOR
gates)
|
3.4.Light Emitting Diodes:
A light-emitting diode (LED) is a semiconductor device that emits visible
light when an electric current passes through it. LED’s
convert electrical energy to light energy. In electronics, polarity indicates whether a circuit component is symmetric or not.
Being diodes, will only allow current to flow in one direction. And when
there’s no current-flow, there’s no light. The positive side of the LED is
called the “anode” and is marked by having a longer
“lead,” or leg. The other, negative side of the LED is called the “cathode.”
4. Circuit Diagram:
For XOR:
For XNOR:
5. Experimentation:
To design & verify XOR Gate:
1. First of all, suitable IC’s for OR, AND &
NOT gate are chosen, i.e. IC 7432 , 7408 & 7404 respectively.
2. Inserted IC’s on the bread board.
3. As there are 14 pins on IC, 7th
pin is grounded and a positive potential is applied to the 14th pin
via a battery of potential less than 5V.
4. Two AND, two NOT and one OR gate can be
chosen to build XOR gate.
5. First input terminal of one AND gate is
connected to the output pin of one NOT gate, the input terminal of the same NOT
gate is connected with the first input of the second AND gate.
6. The output terminal of the second NOT gate is
connected with the second input pin of the second AND gate and Input pin of the
same NOT gate is connected with the second input of first AND gate.
7. A wire is connected to the first terminal of
first AND gate and another is connected to the second pin of the second AND
gate to give input.
8. Input signal is given to the input pins through
a battery
9. Output terminal ( pin 3) of both AND gate is connected
to the input pins of OR gate
10. LED is inserted on bread board with its
positive terminal connected to the output pin (i.e. 2 in our case) of OR gate and
negative signal is given to the other terminal.
11. Initially negative signal is given to both of
the input terminals i.e. 0 is the input at both terminals.
12. Hence in result output is 0 i.e. LED didn’t light
up.
13. Then 0 (negative signal) is given to one
terminal and 1(positive terminal) to the other. LED lights up.
14. As we are working with XOR Gate, that’s why
LED lights up for only in the case when input pins are different.
15. Truth table is drawn.
To verify XNOR Gate:
6. First of all, suitable IC’s for OR, AND &
NOT gate are chosen, i.e. IC 7432 , 7408 & 7404 respectively.
7. Inserted IC’s on the bread board.
8. As there are 14 pins on IC, 7th
pin is grounded and a positive potential is applied to the 14th pin
via a battery of potential less than 5V.
9. Two AND, two NOT and one OR gate can be
chosen to build XOR gate.
10. First input terminal of one AND gate is
connected to the output pin of one NOT gate, the input terminal of the same NOT
gate is connected with the first input of the second AND gate.
11. The output terminal of the second NOT gate is
connected with the second input pin of the second AND gate and Input pin of the
same NOT gate is connected with the second input of first AND gate.
12. A wire is connected to the first terminal of
first AND gate and another is connected to the second pin of the second AND
gate to give input.
13. Input signal is given to the input pins through
a battery
14. Output terminal (pin 3) of both AND gate is
connected to the input pins of OR gate, Output of OR is connected to the input
of NOT gate.
15. LED is inserted on bread board with its
positive terminal connected to the output pin (i.e. 2 in our case) of NOT gate and
negative signal is given to the other terminal.
16. Initially negative signal is given to both of
the input terminals i.e. 0 is the input at both terminals.
17. Hence in result output is 1 i.e. LED lights
up.
18. Then 0 (negative signal) is given to one
terminal and 1(positive terminal) to the other. LED didn’t light up.
19. As we are working with XNOR Gate, that’s why
LED lights up for only in the case when input pins are same.
20. Truth table is drawn.
6. Observations & Calculations:
The truth table for XOR gate which we have observed is shown below:
A
|
B
|
Y
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
0
|
The truth table for XNOR gate which we have observed is shown below:
A
|
B
|
Y
|
0
|
0
|
1
|
0
|
1
|
0
|
1
|
0
|
0
|
1
|
1
|
1
|
7. Results & Discussion:
We have designed XOR and XNOR gate by using different suitable
combinations of AND OR & NOT gate. As we have also verified the truth
tables of XOR & XNOR gate, we can deduce some main points from this. The
total OR & AND logic gates in IC’s 7432 & 7408 respectively are 4, and
6 NOT logic gates in IC 7404. The logic gate whose output entries are 0 when
inputs are same and 1 for different input, is known to be as XOR gate. The gate
which yields 0 when inputs are different and 1 for same inputs is known to be
as XNOR gate. The output of XNOR gate is opposite to that of the output of XOR gate.
NOT gate simply inverted the input operation.
8. Conclusion:
Through this experiment we have designed XOR and XNOR gate and truth
tables of XOR & XNOR Gate are verified by using IC’s inserted on bread
board along with LED to show OFF or ON status of output.
9. References:
IV.
www.electrical4u.com/exclusive-or-gate/
Comments
Post a Comment