HOME WORK 3

PHY112- MODERN PHYSICS AND ELECTRONICS

DOA DOS

PART A

1. Why we define Fermi level for semiconductor junction diodes. Explain Fermi levels in case of n-type and p-type semiconductors with diagrams. What is the difference between simple switch and those of ideal diode?

2. Determine the diode current at 20o C for a silicon diode with IS = 50 nA and an applied forward bias of 0.6V. If the value of the VD is halved, find ID value.

3. (a) Determine the static resistance of the diode at a forward current of 2 mA and 4 mA. Repeat the same calculations for current 15 mA and compare the results. (b) Determine the dynamic resistance of the diode at a forward current of 10 mA. Find the same ac resistance with another method describe in text book and compare the results.

PART B

1. Determine Vo and ID for the networks shown in figures.

2. Given Pmax = 14 mW for each diode of Fig. 3, determine the maximum current rating of each diode (using the approximate equivalent model).

(b) Determine Vmax for Vimax = 160 V.(c) Determine the current through each diode at Vimax using the results of part (b).(e) If only one diode were present, determine the diode current and compare it to the maximum rating.

3. Determine the output waveform

4.