JEE Main · 2021 · 31 Aug 2021 · Shift 2 · Semiconductors

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If VA and VB are the input voltages (either 5 V or 0 V ) and Vo is the output voltage then the two gates represented in the following circuit (A) and (B) are:-

(A)NAND and NOR Gate
(B)OR and NOT Gate✓ Correct
(C)AND and NOT Gate
(D)AND and OR Gate

Answer: (B)

Solution

In circuit (A) the two inputs feed diodes whose outputs are tied together at

V_{0}

across a resistor to ground. If either input is at

5

V its diode conducts and pulls

V_{0}

high;

V_{0}

is low only when both inputs are low, which is the OR operation. In circuit (B) the input drives the base of a common-emitter npn transistor with the collector as

V_{0}

. A high input saturates the transistor and pulls

V_{0}

low, while a low input leaves it cut off so

V_{0}

stays high, which is the NOT operation. The two gates are an OR gate and a NOT gate.

JEE Main · 2021 · 31 Aug 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 31 Aug 2021 · Shift 2 · Semiconductors

Solution

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