Question

1.) Determine the intrinsic carrier density in Germanium and Gallium Arsenide at 27°C The mass of a free electron, mo 9.11 x 10 kg . The Planck's constant, h 6.626 x 10-4J-s or 4.14 x 10s eV-s . The Boltzmann's constant, k 1.38 x 10-23 J/K or 8.617 x 10° eV/K Symbol Germanium Silicon Gallium Arsenide E, (eV)1 0.66 Bandgap energy at 300 K The effective mass of the electrons l m、! 0.55m The effective mass of the holes ma0.37mo 1.12 1.08mo 0.81mo 1.424 0.067mo 0.45mo termine the voltage across the resistor 6kn. Given that the voltage drop across Silicon diodes during forward-biased condition is 0.7 V Si V 10 V 3.) A Zener diode regulator shown below is designed to meet the following specifications: L = 10 mA and Vo-10 V. The source voltage Vs varies from 30 to 50 V. The Zener diode has Vz 10 V and the Zener knee current, l 1 mA. What should be the maximum value of Rs in order to satisfy the voltage regulator operation for any values of Vs in the given range? 10 mA tv 30-50V

Answer 1

"Diode forward biased (V_D > 0.7) Diode Revere biased (V_D < 0.7 given circuit ""In diode circuits we have to assume some state for each diode then do analysis in the end we have to prove the assumption right"" if Diode is assumed ""ON"" then we should show that ""I"" > 0 if Diode is assumed ""OFF"" then we should show open circuit voltage is less than 0.7 i.e V_oc < 0.7 from circuit hence assume D_1: ON D_2: OFF \r\n I = 10 - 0.7/4k + 6k = 9.3/10k = 0.93 m v I > 0 hence assumption correct V_oc = 3- V = 3 - I times 6k = 3 - 0.93m times 6k = 3 - 5.58 V_oc = -2.58 V_oc < 0.7 hence assumption is correct Now let us redraw final circuit and find required things v = I times 6 = 0.93 m times 6k V = 5.58 V "