Question

In the circuit shown in below I = 2mA, VB = 2V and R = 2K. The voltage V will be ________ (Use constant voltage drop model assumption and take VD = 0.5V)

(a) 0V

(b) 2.5V

(c) 6V

(d) 3.5V

I got this question in a national level competition.

The question is from Constant Voltage Drop Model-2 in division Diode Circuit of Analog Circuits

Answer 1

Correct choice is (b) 2.5V

To elaborate: 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.

Since current source forward bases the diode voltage drop across diode is VD. So net voltage output is VD+VB.