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GATE 2025 EC – Question 57

Analog Circuits · Diode Circuits · 2 marks · Multiple select

All the diodes in the circuit given below are ideal.

Which of the following plots is/are correct when $V_I$ (in Volts) is swept from $-M$ to $M$?

Diagram for GATE 2025 EC question 57
  1. Plot (A)
  2. Plot (B)
  3. Plot (C)
  4. Plot (D)

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Show answer and explanation

Correct answer: (A) Plot (A); (D) Plot (D)

Explanation

The diodes form a full-wave bridge: the two diodes with their cathodes on the right node conduct from the input terminal that is positive, and the load current always enters the load from the right, so $V_O=+|V_I|$ (plot A; ideal diodes drop nothing). The input current is $+V_I/R$ when $V_I>0$ and reverses direction when $V_I<0$, so $I_I=V_I/R$, a straight line through the origin (plot D). Plot B ($V_O=V_I$) and plot C ($I_I=|V_I|/R$) would need the current to keep the same direction for both polarities, which the bridge does not do.