📘 Download Multiplexer Notes (PDF)
Click below to jump to the download section and get complete notes on 4:1 and 8:1 Multiplexer with diagrams and explanations.
⬇ Go to Download SectionMultiplexer (MUX)
A multiplexer is a combinational logic circuit that selects one of many input signals and forwards it to a single output line. It works like a digitally controlled switch.
A multiplexer with n select lines can select one out of 2ⁿ input lines.
Basic Concept of Multiplexer
- Multiple data inputs but only one output.
- Select lines decide which input appears at the output.
- Used for data routing and signal selection.
- Also known as a data selector.
4 : 1 Multiplexer
A 4:1 multiplexer has four input lines (I₀–I₃), two select lines (S₁, S₀), and one output (Y). Based on the select inputs, only one data input is connected to the output.
Inputs and Outputs
- Inputs: I₀, I₁, I₂, I₃
- Select lines: S₁, S₀
- Output: Y
Truth Table of 4:1 Multiplexer
| S1 | S0 | Selected Input | Output (Y) |
|---|---|---|---|
| 0 | 0 | I₀ | I₀ |
| 0 | 1 | I₁ | I₁ |
| 1 | 0 | I₂ | I₂ |
| 1 | 1 | I₃ | I₃ |
Logic Expression of 4:1 Multiplexer
-
Output (Y):
\( Y = \overline{S_1}\,\overline{S_0}I_0 + \overline{S_1}S_0 I_1 + S_1\overline{S_0}I_2 + S_1S_0 I_3 \)
Working of 4:1 Multiplexer
- When S₁S₀ = 00 → output = I₀
- When S₁S₀ = 01 → output = I₁
- When S₁S₀ = 10 → output = I₂
- When S₁S₀ = 11 → output = I₃
8 : 1 Multiplexer
An 8:1 multiplexer has eight input lines (I₀–I₇), three select lines (S₂, S₁, S₀), and one output. It selects one of the eight inputs based on the select signals.
Inputs and Outputs
- Inputs: I₀ to I₇
- Select lines: S₂, S₁, S₀
- Output: Y
Truth Table of 8:1 Multiplexer
| S2 | S1 | S0 | Selected Input | Output |
|---|---|---|---|---|
| 0 | 0 | 0 | I₀ | I₀ |
| 0 | 0 | 1 | I₁ | I₁ |
| 0 | 1 | 0 | I₂ | I₂ |
| 0 | 1 | 1 | I₃ | I₃ |
| 1 | 0 | 0 | I₄ | I₄ |
| 1 | 0 | 1 | I₅ | I₅ |
| 1 | 1 | 0 | I₆ | I₆ |
| 1 | 1 | 1 | I₇ | I₇ |
Logic Expression of 8:1 Multiplexer
-
Output (Y):
\( Y = \sum_{i=0}^{7} I_i \cdot m_i \)
(where mᵢ represents the minterm formed by select lines S₂, S₁, S₀)
Applications of Multiplexer
- Data routing in digital systems
- Communication systems
- CPU and ALU design
- Parallel to serial data conversion
- Memory selection
📺 Watch: Multiplexer Explained
📥 Download Multiplexer Notes (PDF)
Download complete notes on 4:1 and 8:1 Multiplexer including:
- Theory and working principle
- Truth tables
- Logic expressions
- Diagrams