The output of the circuit shown is Fig is _______

Question

Question

This question was previously asked in

DFCCIL Executive S&T 2018 Official Paper

Answer 1

Concept:

Multiplexer:

A multiplexer is Many to One data selector
A multiplexer selects one of the many data available at its input depending on the bits on the select line
For 2n inputs, there are n select lines that determine, which input is to be connected to the output.

Example:

A 4-input multiplexer is as shown below.

F1 U.B Madhu 27.03.20 D8

Output,

Y = I0S̅1S̅0 + I1S̅1S0 + I2S1S̅0 + I3S1S0

Where

I0, I1, I2, I1 = Input

S0, S1 = Selection lines

Calculation:

The given figure consists of three 2 × 1 multiplexers.

The general equation for a 2 × 1 multiplexer is:

Y = S̅I₀ + SI₁

F1 Tapesh Madhuri 10.05.2021 D12

The output of first mux will be:

Y₁ = S × 1

as Select line = 1 (given)

Y₁ = 1

Now Y₂ = S̅ × X

as Select line = 0 (given)

Y2 = X

Now

Y = S × X

as Select line = 1 (given)

Y = X

Hence option (2) is the correct answer.