Question

Question 4: By differentiating the rectifier equation for a junction diode, I = Io (e(eVapp/kT) - 1), determine an expression for the junction resistance R = (dI/dV)-1. Given that e/kT = 38V-1 at room temperature, calculate the rectification ratio at a potential of 1V. (Solution: 1033).

Question 5: Consider a silicon diode with n=1.5. Find the change in voltage if current changes from 0.1 mA to 10 mA. Take Io = 10-12 A, VT = kT/e = 25 mV at room temperature. Use I = Io (exp(eVapp/nkT ) expression as I >> Io, the 1 is the expression is neglected. (Solution: Vapp(0.1mA) –Vapp(10mA) = - 0.173V).

Question 6: A diode for which the forward voltage drop is 0.7 V at 1 mA and for which n=1 is operated at 0.5 V. What is the value of the current? Hint: Use I2/I1 = (exp((V2 – V1)/nVT ), VT = kT/e = 25mV. (Solution: 0.335 mA).

Answer 1