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GATE 2014 EC (EC1) – Question 19

Analog Circuits · Diode Circuits · 1 mark · Multiple choice

In the circuit, PN diode D₁ has forward drop 0.7 V and Schottky diode D₂ has forward drop 0.3 V. ON means conducting and OFF means nonconducting. Which states apply?

Diagram for GATE 2014 EC (EC1) question 19
  1. Both D₁ and D₂ ON
  2. D₁ ON, D₂ OFF
  3. Both D₁ and D₂ OFF
  4. D₁ OFF, D₂ ON

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Show answer and explanation

Correct answer: (D) D₁ OFF, D₂ ON

Explanation

Assume only the0.3V Schottky diode D2 conducts. Its series current is(10−0.3)/(1000+20)=9.5098mA. The node at the PN diode D1 is then0.3+20×0.0095098=0.4902V, below its0.7V turn-on voltage. The assumption is consistent: **D1off,D2on,D**.