Name ID
Muhammad Numan Yousaf 13003065009
Qasim Shehzad 13003065028
Waqar-ul-Malik 13003065050
Seharyar Munir 13003065049
Haseeb-ur-Rehman 13003065034
Multiplexer and De-Multiplexer
• A multiplexer is a circuit that accept many input but giveonly one output. A de-multiplexer function exactly in thereverse of a multiplexer, that is a de-multiplexer acceptsonly one input and gives many outputs. Generallymultiplexer and de-multiplexer are used together, becauseof the communication systems are bi directional.
Multiplexer
Multiplexer means manyinto one. A multiplexer is acircuit used to select androute any one of the severalinput signals to a signaloutput. An simple exampleof an non electronic circuitof a multiplexer is a singlepole multi position switch.
Single Pole Multi Position Switch
Uses of Multiplexers
Multi-position switches arewidely used in manyelectronics circuits. Howevercircuits that operate at highspeed require the multiplexerto be automatically selected. Amechanical switch cannotperform this task satisfactorily.Therefore, multiplexer used toperform high speed switchingare constructed of electroniccomponents. Multiplexer
Types of Multiplexer
• Multiplexer handle two type of data that is analogand digital. For analog application, multiplexerare built of relays and transistor switches. Fordigital application, they are built from standardlogic gates.
• The multiplexer used for digital applications, alsocalled digital multiplexer, is a circuit with manyinput but only one output. By applying controlsignals, we can steer any input to the output. Fewtypes of multiplexer are 2-to-1, 4-to-1, 8-to-1, 16-to-1 multiplexer.
4-to-1 Multiplexer
The 4-to-1 multiplexer has 4 input bit, 2 control bits, and 1 output bit. The four input bits are I0,I1,I2 and I3. only one of this is transmitted to the output y. The output depends on the value of S0 and S1 which is the control input. The control input determines which of the input data bit is transmitted to the output.
4-to-1 multiplexer
4-to-1 Multiplexer
• An example of 4-to-1 multiplexer is IC 74153 in which the output is same as the input.
• Another example of 4-to-1 multiplexer is 45352 in which the output is the compliment of the input.
• Example of 16-to-1 line multiplexer is IC74150.
Applications of Multiplexer
• Multiplexer are used in various fields where multiple data need to be transmitted using a single line. Following are some of the applications of multiplexers
• Communication system
• Telephone network
• Computer memory
• Transmission from the computer system of a satellite
De-multiplexer
De-multiplexer means one tomany. A de-multiplexer is acircuit with one input andmany output. By applyingcontrol signal, we can steerany input to the output. Fewtypes of de-multiplexer are 1-to 2, 1-to-4, 1-to-8 and 1-to16 de-multiplexer 1-to-4
De- multiplexer
Applications of De-Multiplexer
• De-multiplexer is used to connect a single source to multiple destinations. The main application area of de-multiplexer is communication system where multiplexer are used.
• Communication System
• ALU (Arithmetic Logic Unit)
• Serial to parallel converter
Decoders
A decoder has N inputs
2N outputs
A decoder selects one of 2N outputs by decoding the binary value on the N inputs.
The decoder generates all of the min-terms of the N input variables.
Exactly one output will be active for each combination of the inputs.
Decoders
•A decoder is a logic circuit that accepts a set of inputs that
represents a binary number and activates only the output that
corresponds to the input number.
•In other words, a decoder circuit looks at its inputs,
determines which binary number is present there, and activates
the one output that corresponds to that number ; all other
outputs remain inactive
General decoder diagram
# There are 2N possible input combinations, from A0 to AN1.
For each of these input combinations only one of the M outputs will be activeHIGH (1), all the other outputs are LOW (0).
Decoders
A B W X Y Z
0 0 1 0 0 0
0 1 0 1 0 0
1 0 0 0 1 0
1 1 0 0 0 1
Active-high outputs
BW
X
Y
Z
I0
I1A
Out0
Out1
Out2
Out3
W = A'.B'
X = A.B'
Y = A'.B
Z = A.Bmsb
2-to-4 Decoder
• A 2-to-4 Decoder▫ 2 inputs (A1, A0)
▫ 22 = 4 outputs (D3, D2, D1, D0)
▫ Truth Table
A1 A0 D0 D1 D2 D3
0 0 1 0 0 0
0 1 0 1 0 0
1 0 0 0 1 0
1 1 0 0 0 1
2-to-4 Decoder with Enable
EN
A1 A0 D0 D1 D2 D3
0 X X 0 0 0 0
1 0 0 1 0 0 0
1 0 1 0 1 0 0
1 1 0 0 0 1 0
1 1 1 0 0 0 1
Truth Table
3-to-8 Decoder
A2
A1 A0
D0
D1
D2
D3
D4
D5
D6
D7
0 0 0 1 0 0 0 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0
0 1 0 0 0 1 0 0 0 0 0
0 1 1 0 0 0 1 0 0 0 0
1 0 0 0 0 0 0 1 0 0 0
1 0 1 0 0 0 0 0 1 0 0
1 1 0 0 0 0 0 0 0 1 0
1 1 1 0 0 0 0 0 0 0 1
3-to-8 Decoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
Encoders An encoder has
2N inputs
N outputs
An encoder outputs the binary value of the selected (or active) input.
An encoder performs the inverse operation of a decoder.
Issues What if more than one input is active?
What if no inputs are active?
Encoders
A B C D Y Z
0 0 0 1 0 0
0 0 1 0 0 1
0 1 0 0 1 0
1 0 0 0 1 1
D
Z
Y
I0
I1C
B I2
I3A
Out0
Out1
Priority Encoders
If more than one input is active, the higher-order input has priority over the lower-order input.
The higher value is encoded on the output
A valid indicator, d, is included to indicate whether or not the output is valid.
Output is invalid when no inputs are active
d = 0
Output is valid when at least one input is active
d = 1
8-to-3 Encoder (truth table)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
8-to-3 Encoder (truth table)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
10000000
000
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
8-to-3 Encoder (truth table)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
01000000
100
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
8-to-3 Encoder (truth table)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
00000100
101
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
8-to-3 Encoder (truth table)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
00000001
111
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
8-to-3 Encoder (equations)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
Note: This truth table is not complete! Why?
Output equations:
A0 = ?A1 = ?A2 = ?
8-to-3 Encoder (equations)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
Output equations:
A0 = D1 + D3 + D5 + D7
A1 = ?A2 = ?
8-to-3 Encoder (equations)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
Output equations:
A0 = D1 + D3 + D5 + D7
A1 = D2 + D3 + D6 + D7
A2 = ?
8-to-3 Encoder (equations)
8-to-3
Encoder
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
inputs outputs
D7 D6
D5 D4
D3
D2
D1 D0
A2 A1 A0
0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 1 0 0 0 1
0 0 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1 1
0 0 0 1 0 0 0 0 1 0 0
0 0 1 0 0 0 0 0 1 0 1
0 1 0 0 0 0 0 0 1 1 0
1 0 0 0 0 0 0 0 1 1 1
Output equations:
A0 = D1 + D3 + D5 + D7
A1 = D2 + D3 + D6 + D7
A2 = D4 + D5 + D6 + D7
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