The GATE Grind

GATE 2026 PH – Question 44

Electronics · basics of digital logic circuits, combinational and sequential circuits, flip- flops, timers, counters, registers, A/D and D/A conversion. · 2 marks · Multiple choice

Considering the circuit and the associated signals measured at different pins (numbered as 1, 2, 3, 4, 5) shown in the figure, the correct option is

Two NOT gates and a NOR gate, with measured pin 1–5 voltage traces.
  1. NOT gate between pins 1 and 2 is faulty.
  2. NOR gate is faulty.
  3. NOT gate between pins 4 and 5 is faulty.
  4. The NOR and output NOT gates, are both faulty.

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Show answer and explanation

Correct answer: (B) NOR gate is faulty.

Explanation

The first inverter output is the complement of pin 1, and pin 5 is the complement of pin 4. During an interval where pin 2 and pin 3 are both high, pin 4 is high instead of the NOR-required low. Thus the NOR gate is faulty.