🔹 What is a Demultiplexer?

Digital Circuit for Data Distribution

Definition

A Demultiplexer (DeMUX) is the opposite of a Multiplexer (MUX).

🔄 Comparison:

  • MUX: Many inputs → One output
  • DeMUX: One input → Many outputs

👉 So a Demultiplexer takes a single input and sends it to one of many outputs, based on select lines.

Example: 1-to-2 Demultiplexer

Inputs
  • 1 data input → D
  • 1 select line → S
Outputs
  • 2 outputs → Y0, Y1
Truth Table for 1-to-2 DeMUX
Select (S) Y0 Y1
0 D 0
1 0 D

👉 If S=0, input D goes to Y0.

👉 If S=1, input D goes to Y1.

Logic Equations
Y0 = D · S'
Y1 = D · S

Where ' means NOT and · means AND.

Block Diagram

D
(Input)
→
1:2
DeMUX
→
Y0
→
Y1
S
(Select)
→

Explained in Words:

  • One input line → D
  • One control line → S
  • Two outputs → Y0 and Y1
  • Depending on S, the input goes to the correct output

Real-Life Analogy

💧 Think of a water tank with one pipe (input) and a valve (select line) that can send water to either Tank A (Y0) or Tank B (Y1).

  • If valve = 0 → water flows into Tank A
  • If valve = 1 → water flows into Tank B
Water Tank
Input (D)
Valve
Select (S)
Tank A
Output (Y0)
Tank B
Output (Y1)

Applications of Demultiplexers

Data Routing

Send data from one source to multiple destinations.

Communication Systems

Distribute signals (e.g., TV broadcasting).

CPU & Memory Systems

Send instructions/data to specific memory locations.

Control Systems

One control signal can activate multiple devices (but only one at a time).

Digital Systems

Distribute clock signals or enable signals to different parts of a circuit.

Serial-to-Parallel Conversion

Convert serial data into parallel form for processing.

MUX vs DeMUX Comparison

  • TV remote selecting channels
  • Water valve directing water flow
    • Feature Multiplexer (MUX) Demultiplexer (DeMUX)
    Function Selects one of many inputs Distributes one input to many outputs
    Inputs Multiple (2^n) Single
    Outputs Single Multiple (2^n)
    Select Lines n n
    Analogy

    Summary

    🔹 Demultiplexer (DeMUX): The opposite of a Multiplexer (MUX)

    🔹 MUX: Many inputs → One output

    🔹 DeMUX: One input → Many outputs

    🔹 Example: 1-to-2 DeMUX → Output depends on select line

    🔹 Applications: Data routing, communication systems, CPU & memory systems, control systems

    Demultiplexers are essential components in digital systems, enabling efficient data distribution from a single source to multiple destinations based on control signals.