Q:    A specific diode conducts 1A at a junction voltage of 0.65 VG & 2A at junction voltage 0.67 V. What is its values of n & Is , what current shall pass if its junction voltage is 0.7 V?

Solution:

                                                             I = I_s e ^V_D ^/nV_T   -------------- (i)

                                                     V_D is diode voltage.

                                                            V_T= 25 mV=0.025 volts

Put the value in eq                                      1= I_s e ^{0.65/n(0.025)} -------------- (ii)

                                                                        2 = I_s e ^{0.067/n(0.025)} ------------- (iii)

                                                                        2 = e ^{0.02/n(0.025)}

                                                from equation (ii )& (iii) we get

                                                                          n = 0.02/0.025ln2 =1.154

                                                By putting the value of n in equation (ii) we get

                                                             Is = e ^-0.65/1.154(0.025)

                                                                         = 1.64 x 10^-10

                                                therefore from equation (i) we have

                                                                    I_D = 1.64 x10^-10 e ^{0.7/1.154(0.025)} = 5.66A