The GATE Grind

GATE 2021 BM – Question 16

Analog and Digital Electronics · Combinational Logic · 1 mark · Multiple choice

Y=Y₁Y₀ is the two-bit output of the combinational circuit shown. What is the maximum value of Y for digital inputs A₁A₀ and B₁B₀?

Diagram for GATE 2021 BM question 16
  1. 01
  2. 10
  3. 00
  4. 11

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) 01

Explanation

Let a=A₀ OR A₁ and b=B₀ OR B₁. The intermediate XOR is c=a XOR b. The two AND outputs are ac and bc. They cannot both be one, because c=1 means a and b differ. Their final AND Y₁ is therefore always zero; their XOR Y₀ can be one. Maximum binary output is 01, A.

More Combinational Logic questions

All Combinational Logic questions →