Q3) Multiplexer

A multiplexer is a device that selects one of several analog or digital input signals and forwards the selected input into a single line. A multiplexer of 2ⁿ inputs has n select lines, which are used to select which input line to send to the output.

Please design the entity as well as the test bench for a 4-to-1 multiplexer. For this multiplexer, please use the following to refer to the inputs/outputs of the circuit: I3, I2, I1, I0 as data inputs; S1 and S0 as selection inputs; and out0 as data output.

Your entity design is:

Your test bench design is:

In your test bench design, please enable each one of the 4 inputs at one time. For example enable I0 to go through the multiplexer first by letting S1 = 0 and S0 = 0. For this case, set I0 to be at 0 for 50ns, and then 1 for 50ns. After this, change S1, S0 values to let I1 (go through 0 and 1 each for 50ns), I2 (go through 0 and 1 each for 50ns), and I3 (go through 0 and 1 each for 50ns) pass the multiplexer correspondingly.

The result waveforms are:

Please select the signals to be simulated in the following order: S1, S0, I3, I2, I1, I0, Out0.