Question

Find current I through the circuit using characteristic equation of diode. The terminal voltage of each diode is 0.6V. Reverse saturation current is 10^-12A.

(a) 0.84mA

(b) 1.84mA

(c) 2.35mA

(d) 3.01mA

This question was posed to me by my college director while I was bunking the class.

This interesting question is from Characteristic Equation of Diode-1 in chapter Diode Circuit of Analog Circuits

Answer 1

The correct choice is (b) 1.84mA

Best explanation: Let VD be the voltage of diode, then by Kirchoff’s loop rule

3V = 2VD + IR1

This method of assumption contains small error but it is the simplest method.

Let VD be 0.6V. Now the current I = (3-1.2)/1k = 1.8mA.

The VD = VT ln((I/IO)+1) = 0.58V

Hence current is (3-(2×0.58))/1k = 1.84mA.