JEE Main 2014 · 19 Apr · Shift 1 · Physics Q28

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PhysicsSingle correct+4 / -1Question 28 of 90

Given : A and B are input terminals.

Logic 1 = > 5 V

Logic 0 = < 1 V

Which logic gate operation, the following circuit does ?

Inputs A and B each connect through a diode (cathode towards the input) and a 50 Ω resistor to a common node, which goes up to V_cc = 6 V and out to V_out, and down through R = 10 kΩ to ground.

AND Gate

OR Gate

XOR Gate

NOR Gate

Answer and worked solution

Official answer: A

If either input is at logic 0, its diode is forward biased and pulls $V_{out}$ down to about the input level (low). Only when both inputs are high are both diodes reverse biased, and $V_{out}$ is pulled up to $V_{cc}$ . Output high only for A = B = 1: an AND gate.

Topics:Logic gates Semiconductors and p-n junction

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JEE Main 2014 · 19 Apr · Shift 1, Physics question 28