GATE 2026 IN – Question 55

Digital Electronics · Number systems and combinational logic · 2 marks · MTA

Which of the following functions represent(s) the output of the CMOS logic gate shown in the circuit below?

$f=\overline A+\overline B\,\overline C$
$f=\overline{A+BC}$
$f=\overline A(\overline B+\overline C)$
$f=\overline{A(B+C)}$

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Correct answer: MTA

Explanation

The pull-down network conducts when the series A–B path conducts or the C path conducts. Thus its conduction condition is $AB+C$, and the intended output is $f=\overline{AB+C}=\overline C(\overline A+\overline B)$.

None of the printed choices equals this function. The official final key awards **marks to all**, which is preserved.