Question

If current source produces a current of 1mA and resistance R is 3K then voltage across the resistor is ____________ (Use constant voltage drop model of diode and take VD as 0.5V)

(a) 3V

(b) 0V

(c) 0.5V

(d) 0.3V

This question was posed to me during an interview.

My question is based upon Constant Voltage Drop Model-1 in division Diode Circuit of Analog Circuits

Answer 1

The correct option is (c) 0.5V

The explanation is: In constant voltage drop model at forward bias diode can be replaced as a cell and in reverse bias diode can be avoided by considering the terminals are open.

The diode is forward biased and drop across it is 0.5V. Maximum current flows through the diode and thus the voltage across diode is same as that across the resistor = 0.5V.