Demultiplexer MCQ Quiz - Objective Question with Answer for Demultiplexer - Download Free PDF

Explanation:

How many select lines are required for a 1-to-8 Demultiplexer?

 A demultiplexer, or demux, is a combinational logic circuit designed to take a single input line and route it to one of several output lines. The specific output line to which the input is routed is determined by the select lines. A 1-to-8 demultiplexer has one input, eight outputs, and a set of select lines that determine which output line the input is sent to.

8 = 2^m

To find m, we take the logarithm base 2 of both sides:

log₂(8) = m

Since 2³ = 8, we find that:

m = 3

Therefore, 3 select lines are required for a 1-to-8 demultiplexer.

Explanation:

1-to-4 Demultiplexer

Definition: A 1-to-4 demultiplexer is a digital switch that takes a single input and directs it to one of four outputs based on the values of two select lines (S1 and S0). It is used to distribute data from one input to one of several output lines.

Working Principle: The 1-to-4 demultiplexer works by using the values of the select lines to determine which output line will receive the input signal. The select lines (S1 and S0) are binary values that can represent one of four possible combinations (00, 01, 10, 11). Based on these combinations, the input is directed to the corresponding output.

Case Analysis:

• If S1 = 0 and S0 = 0, the input I is directed to Output 0.
• If S1 = 0 and S0 = 1, the input I is directed to Output 1.
• If S1 = 1 and S0 = 0, the input I is directed to Output 2.
• If S1 = 1 and S0 = 1, the input I is directed to Output 3.

Given the input conditions: I = 1, S1 = 1, and S0 = 0, we can analyze which output will be active.

Step-by-Step Solution:

1. Identify the binary combination of the select lines:

S1 = 1 and S0 = 0 corresponds to the binary combination "10".

2. Determine which output corresponds to the binary combination "10":

From the case analysis above, we know that the combination "10" directs the input to Output 2.

3. Apply the input to the determined output:

Since I = 1, Output 2 will receive the input signal and will be set to 1, while all other outputs will remain 0.

Therefore, the output values will be:

• Output 0 = 0
• Output 1 = 0
• Output 2 = 1
• Output 3 = 0

Correct Option: Option 4 (Output 0 = 0, Output 1 = 0, Output 2 = 1, Output 3 = 0)

De-multiplexer:

• The demultiplexer is a combinational logic circuit designed to switch one common input line to one of several separate output lines.
• The data distributor, known as a Demultiplexer or “Demux”, works in just the opposite way to that of the Multiplexer.
• The demultiplexer takes one single input data line and then switches it to any one of a number of individual output lines one at a time.
• A demultiplexer circuit is a decoder circuit with enable input.

The block diagram is as shown:

Application:

The demultiplexer converts a serial data signal at the input to parallel data at its output lines as shown below.

The function of the Demultiplexer is to switch one common data input line to any one of the 4 output data lines A to D.

Important Points

Multiplexer:

The multiplexer is a combinational logic circuit designed to switch one of several input lines to a single common output line.

• The multiplexer or “MUX” is a combinational logic circuit designed to switch one of several input lines through a single common output line by the application of a control signal.
• Multiplexers operate like very fast acting multiple position rotary switches connecting or controlling multiple input lines called “channels” one at a time to the output.
• Multiplexers are used to convert parallel to serial data.

Correct Answer :- n = 2m

Multiplexer: It is a device that combines several inputs and outputs them into a single line.

Demultiplexer: It is a device that reverses the process of multiplexer i.e. it converts data from a single input line to multiple output lines.

There are 2^m possible combinations of select lines, and each combination routes the input to one of the n output lines.

Therefore, the demultiplexer has n output lines and 2^m select lines.

correct option is 3

Concept:

A demultiplexer is a circuit that can distribute and deliver multiple outputs from a single input. (option 2 is the correct statement)

A 1-line to 8-line demultiplexer consists of 3 selection lines, eight and gates, all of which are connected to a single input data line. (option 1 is the correct statement)​                             ​

From the above figure, demultiplexer takes one input data source and selectively distributes it to 1-of-N output channels just like a multi-position switch. (option 4 is the correct statement) 

It is not used as anti-clock demultiplexers in synchronous data transmission systems in the receivers and security monitoring systems etc. (option 3 is an incorrect statement) Additional Informationsynchronous data transmission is a data transfer method in which a continuous stream of data signals is accompanied by a timing signal to ensure that the transmitter and the receiver are in step (synchronized) with each other.

correct option is 3

Concept:

A demultiplexer is a circuit that can distribute and deliver multiple outputs from a single input. (option 2 is the correct statement)

A 1-line to 8-line demultiplexer consists of 3 selection lines, eight and gates, all of which are connected to a single input data line. (option 1 is the correct statement)​                             ​

From the above figure, demultiplexer takes one input data source and selectively distributes it to 1-of-N output channels just like a multi-position switch. (option 4 is the correct statement) 

It is not used as anti-clock demultiplexers in synchronous data transmission systems in the receivers and security monitoring systems etc. (option 3 is an incorrect statement) Additional Informationsynchronous data transmission is a data transfer method in which a continuous stream of data signals is accompanied by a timing signal to ensure that the transmitter and the receiver are in step (synchronized) with each other.

• The IC 74LS138 is a 3 to 8 line decoder integrated circuit from the 74xx family. 
• The main function of this IC is to decode otherwise demultiplex the applications.
• The decoder 74LS138 IC uses advanced technology like silicon (Si) gate TTL technology.
• 74LS138 IC has 3 binary select inputs like A, B & C. If the IC is activated, then these input pins will decide which of the 8 usually HIGH outputs will go LOW.
• As this IC includes three enable pins (where two pins are active low and one is active high) the necessity of outside gates is not there. 
• These are suitable for applications like memory address decoding, data routing, etc. 

Important Points

• Two IC 74LS83 is required to design an 8-bit adder/8-bit subtractor
• IC 74152 is an 8:1 Multiplexer.

De-multiplexer:

• The demultiplexer is a combinational logic circuit designed to switch one common input line to one of several separate output lines.
• The data distributor, known as a Demultiplexer or “Demux”, works in just the opposite way to that of the Multiplexer.
• The demultiplexer takes one single input data line and then switches it to any one of a number of individual output lines one at a time.
• A demultiplexer circuit is a decoder circuit with enable input.

The block diagram is as shown:

Application:

The demultiplexer converts a serial data signal at the input to parallel data at its output lines as shown below.

The function of the Demultiplexer is to switch one common data input line to any one of the 4 output data lines A to D.

Important Points

Multiplexer:

The multiplexer is a combinational logic circuit designed to switch one of several input lines to a single common output line.

• The multiplexer or “MUX” is a combinational logic circuit designed to switch one of several input lines through a single common output line by the application of a control signal.
• Multiplexers operate like very fast acting multiple position rotary switches connecting or controlling multiple input lines called “channels” one at a time to the output.
• Multiplexers are used to convert parallel to serial data.

Explanation:

1-to-4 Demultiplexer

Definition: A 1-to-4 demultiplexer is a digital switch that takes a single input and directs it to one of four outputs based on the values of two select lines (S1 and S0). It is used to distribute data from one input to one of several output lines.

Working Principle: The 1-to-4 demultiplexer works by using the values of the select lines to determine which output line will receive the input signal. The select lines (S1 and S0) are binary values that can represent one of four possible combinations (00, 01, 10, 11). Based on these combinations, the input is directed to the corresponding output.

Case Analysis:

• If S1 = 0 and S0 = 0, the input I is directed to Output 0.
• If S1 = 0 and S0 = 1, the input I is directed to Output 1.
• If S1 = 1 and S0 = 0, the input I is directed to Output 2.
• If S1 = 1 and S0 = 1, the input I is directed to Output 3.

Given the input conditions: I = 1, S1 = 1, and S0 = 0, we can analyze which output will be active.

Step-by-Step Solution:

1. Identify the binary combination of the select lines:

S1 = 1 and S0 = 0 corresponds to the binary combination "10".

2. Determine which output corresponds to the binary combination "10":

From the case analysis above, we know that the combination "10" directs the input to Output 2.

3. Apply the input to the determined output:

Since I = 1, Output 2 will receive the input signal and will be set to 1, while all other outputs will remain 0.

Therefore, the output values will be:

• Output 0 = 0
• Output 1 = 0
• Output 2 = 1
• Output 3 = 0

Correct Option: Option 4 (Output 0 = 0, Output 1 = 0, Output 2 = 1, Output 3 = 0)

Explanation:

How many select lines are required for a 1-to-8 Demultiplexer?

 A demultiplexer, or demux, is a combinational logic circuit designed to take a single input line and route it to one of several output lines. The specific output line to which the input is routed is determined by the select lines. A 1-to-8 demultiplexer has one input, eight outputs, and a set of select lines that determine which output line the input is sent to.

8 = 2^m

To find m, we take the logarithm base 2 of both sides:

log₂(8) = m

Since 2³ = 8, we find that:

m = 3

Therefore, 3 select lines are required for a 1-to-8 demultiplexer.

DEMUX:

A demultiplexer (or demux) is a device that takes a single input line and routes it to one of several digital output lines.

It consists of 2ⁿ outputs and has n selection lines, which are used to select which output line to send the input. It is also called as a data distributor.

Additional Information

For 1:4 DEMUX

Select lines: A, B

Output: D₀, D₁, D₂, D₃

Truth table:-

correct option is 3

Concept:

A demultiplexer is a circuit that can distribute and deliver multiple outputs from a single input. (option 2 is the correct statement)

A 1-line to 8-line demultiplexer consists of 3 selection lines, eight and gates, all of which are connected to a single input data line. (option 1 is the correct statement)​                             ​

From the above figure, demultiplexer takes one input data source and selectively distributes it to 1-of-N output channels just like a multi-position switch. (option 4 is the correct statement) 

It is not used as anti-clock demultiplexers in synchronous data transmission systems in the receivers and security monitoring systems etc. (option 3 is an incorrect statement) Additional Informationsynchronous data transmission is a data transfer method in which a continuous stream of data signals is accompanied by a timing signal to ensure that the transmitter and the receiver are in step (synchronized) with each other.

• The IC 74LS138 is a 3 to 8 line decoder integrated circuit from the 74xx family. 
• The main function of this IC is to decode otherwise demultiplex the applications.
• The decoder 74LS138 IC uses advanced technology like silicon (Si) gate TTL technology.
• 74LS138 IC has 3 binary select inputs like A, B & C. If the IC is activated, then these input pins will decide which of the 8 usually HIGH outputs will go LOW.
• As this IC includes three enable pins (where two pins are active low and one is active high) the necessity of outside gates is not there. 
• These are suitable for applications like memory address decoding, data routing, etc. 

Important Points

• Two IC 74LS83 is required to design an 8-bit adder/8-bit subtractor
• IC 74152 is an 8:1 Multiplexer.

De-multiplexer:

• The demultiplexer is a combinational logic circuit designed to switch one common input line to one of several separate output lines.
• The data distributor, known as a Demultiplexer or “Demux”, works in just the opposite way to that of the Multiplexer.
• The demultiplexer takes one single input data line and then switches it to any one of a number of individual output lines one at a time.
• A demultiplexer circuit is a decoder circuit with enable input.

The block diagram is as shown:

Application:

The demultiplexer converts a serial data signal at the input to parallel data at its output lines as shown below.

The function of the Demultiplexer is to switch one common data input line to any one of the 4 output data lines A to D.

Important Points

Multiplexer:

The multiplexer is a combinational logic circuit designed to switch one of several input lines to a single common output line.

• The multiplexer or “MUX” is a combinational logic circuit designed to switch one of several input lines through a single common output line by the application of a control signal.
• Multiplexers operate like very fast acting multiple position rotary switches connecting or controlling multiple input lines called “channels” one at a time to the output.
• Multiplexers are used to convert parallel to serial data.

Multiplexer: Multiplexer is a device that has multiple inputs and single line output.

De-multiplexer: De-multiplexer is a device that has a signal inputs line and multiple line outputs.

The given figure has one input and two outputs. Hence it is De-multiplexer.

Combinational circuit:

• Combinational and sequential circuits are the digital circuits made using logic gates
• Present output depends on the present input only
• No feedback is present
• No memory is present

Encoder: Encoder is used to converter other codes to binary