Exam-1_Student_F07_Sol

# Exam-1_Student_F07_Sol - is 0.675 V(b What will be the...

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ECE 271- Fall 2007 Exam-I (10/10/2007) Solutions Prof. Hanafi 1) Use current and voltage division to find I 1 , I 2 and V 3 , in the circuit in Fig. 1 if I = 5 mA , R 1 = 2.4 k Ω , R 2 = 5.6 k Ω , and R 3 = 3.6 k Ω . (15 points) Figure 1 2) A silicon sample is supporting an electric field of -2000V/cm, and the mobilities of electrons and holes are 1000 and 400 cm 2 /V.s, respectively. What are the electron and hole velocities? If p = 10 17 / cm 3 , and n = 10 3 / cm 3 , what are the electron and hole current densities? (15 points)

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3) Suppose a semiconductor has N D = 10 16 /cm 3 , N A = 5 × 10 16 / cm 3 , and n i = 10 11 /cm 3 . What are the electron and hole concentrations? (10 points) 4) A diode has I S = 10 -17 A and n = 1. (a) What is the diode current if the diode voltage

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Unformatted text preview: is 0.675 V? (b) What will be the diode voltage if the current increases by a factor of 3? (10 points) 5) Plot the load line and find the Q-point for the diode circuit in Fig. 2 if (a) V = 6 V and R = 4 k Ω . (b) For V = -6 V and R = 3 k Ω . . Use the i-v characteristic in Fig. 3. (20 points) Figure 2 Figure 3 6) (a) Find I and V for the circuit in Fig. 4 using the ideal diode model. (b) Repeat using the constant voltage drop model with V on = 0.7 V. (10 points) 16 K Ω Figure 4 (a) (b) 7) Find the Q-points for the diodes in the circuit in Fig. 5 using the constant voltage drop model with V on = 0.6 V. (20 points) 8.2 K Ω 12 K Ω 10 K Ω Figure 5...
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## This note was uploaded on 04/07/2008 for the course ECE 271 taught by Professor Hanafi during the Spring '05 term at NJIT.

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Exam-1_Student_F07_Sol - is 0.675 V(b What will be the...

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