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digital electronics · combinational logic

4-to-1 Multiplexer

A 4-to-1 multiplexer uses two binary select inputs to choose one of four data inputs. Each select combination maps to one input, then routes that value to Y. The circuit is common in digital systems that need to share a bus, select an operating mode or implement a small truth table. This example keeps the data sources and select states visible so the selection relationship is clear. The same structure scales: an 8-to-1 multiplexer needs three select bits, while a 16-to-1 multiplexer needs four.

Type Circuit schematicStandard IEEE Std 315 / ANSI Y32.2Engine schematex-circuitUpdated 9/24/2026
4-to-1 Multiplexer
Drawing preview
The request

“Draw a 5 V 4-to-1 multiplexer with I0 through I3 data inputs, select lines S0 and S1, and output Y with a 10 kΩ load to ground.”

Then trySet I2 to 5 V.Add an active-low enable input.
What is in this drawing

Read the decisions behind it.

01Four inputs

I0 through I3 provide selectable data.

02Two select bits

S0 and S1 encode one of four choices.

03Output Y

The selected input appears at one output.

Use this for a four-source digital signal selector.

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FAQ

Common questions

Why does a 4-to-1 MUX need two select lines?

Two binary bits represent four possible selections.

What do I0 through I3 mean?

They are the four data inputs available to the multiplexer.

Can it select analog signals?

This logic example selects digital levels; analog multiplexers use different switch circuitry.