Question

What is meant by demultiplexer?

Answer 1

A **demultiplexer** (often abbreviated as **demux**) is a digital electronic device or circuit that takes a single input signal and routes it to one of several output lines based on a set of control signals. It performs the reverse operation of a multiplexer, which combines multiple inputs into a single output.

### **Key Features of a Demultiplexer**
1. **Input Signal:** A single input data line.
2. **Control Signals:** A set of select lines that determine which output line the input signal is routed to.
3. **Output Lines:** Multiple output lines, only one of which is active at any given time.

### **How It Works**
The demultiplexer uses the control signals (or select lines) to decide which output line will carry the input signal. For example:
- If there are **n control lines**, the demultiplexer can have \(2^n\) output lines.
- The binary value of the control lines determines the active output line.

#### Example: 1-to-4 Demultiplexer
- **Input:** 1 data line
- **Control Lines:** 2 lines (can represent 4 states: 00, 01, 10, 11)
- **Output Lines:** 4 lines (Y0, Y1, Y2, Y3)

The control signals dictate:
- If the control signal is `00`, the input is routed to **Y0**.
- If the control signal is `01`, the input is routed to **Y1**, and so on.

### **Applications**
1. **Data Routing:** Sending data to one of many devices or destinations.
2. **Communication Systems:** Splitting data streams to multiple receivers.
3. **Memory Systems:** Selecting memory locations for reading or writing.
4. **Logic Circuit Design:** Used in implementing Boolean functions or decoding operations.

### **Truth Table**
For a 1-to-4 demultiplexer:

| Control Signals (Select Lines) | Active Output Line |
|--------------------------------|--------------------|
| 00                             | Y0                 |
| 01                             | Y1                 |
| 10                             | Y2                 |
| 11                             | Y3                 |

### **Symbol**
A demultiplexer is typically represented as a triangle pointing towards multiple outputs, with a single input on one side and multiple outputs branching out on the opposite side.

### **Real-Life Analogy**
Think of a demultiplexer as a switchboard in a telephone system. A single call (input signal) can be directed to one of several recipients (output lines) based on the number dialed (control signals).