Question

Find the temperature at which a diode current is 2mA for a diode which has reverse saturation current of 10^-9 A. The ideality factor is 1.4 and the applied voltage is 0.6V forward bias.

(a) 69.65°C

(b) 52.26°C

(c) 25.23°C

(d) 70.23°C

I have been asked this question in exam.

My doubt stems from Characteristic Equation of Diode-1 topic in chapter Diode Circuit of Analog Circuits

Answer 1

The correct answer is (a) 69.65°C

Easiest explanation: Equation for diode current

I=I0×(e^(V/ηVT)-1)  where I0 = reverse saturation current

             η = ideality factor

             VT = thermal voltage

             V = applied voltage

I0 = 10^-9A, η = 1.4, V = 0.6V, I = 2mA

We know thermal voltage VT = TK/11600. Therefore, TK = VTx11600 = 0x11600 = 342.65K = 69.65°C.