Download ECE 250 Homework #3: Semiconductor Diodes and Circuits - Prof. Marc E. Herniter and more Assignments Electrical and Electronics Engineering in PDF only on Docsity!
ECE 250 Homework
Due 9/23/
Problem 1: A GaAs PN junction diode has a donor doping concentration of Nd=10^16 /cm^3 and an acceptor doping concentration of
Na=10^16 /cm^3. Plot the built-in barrier potential for this diode for temperatures from 0 °C to 70 °C. Should the y-axis be plotted in a log scale? Why or why not?
Problem 2: For the circuit below, find the diode voltage and current using: a) Iteration b) Maple or MathCAD. c) PSpice. See section 3.C in the PSpice manual for an example. For the diode let Is = 3.7× 10 -14^ A and η=1.2. In PSpice, the model parameter for η is N.
Vin 15 V
D
R
1k
R 5k
Problem 3:
a) By hand, plot Vo(t) and Vin(t) for the circuits below. Let Vin be a +/- 15 Volt triangle wave. b) By hand, plot the transfer curve Vo versus Vin for the circuits below. You may assume that the diodes are ideal.
Circuit 1
D
D
Vout
D
R
1k
R
1k
R
Vin
Circuit 2
R
1k
D
+^ Vout
R
Vin
D
R 1k
Circuit 3
R
1k
Vin D
+^ Vout
R 3k
D
D
R
1k
D
Problem 4: Use PSpice to plot Vo(t) and Vin(t) versus time for the circuits of problem 4. Let Vin(t) be a +/- 15 Volt triangle wave. Plot both traces on the same plot. You will need to use Probe to generate these plots. See Chapter 2 of the PSpice manual for examples using Probe. See Section 6.F of the PSpice manual for an example. Use the following parts: Vtri, R, and D_ideal. Make sure that you use part 0 for ground.
Problem 5: Answer the following questions: a. What is an intrinsic semiconductor. b. What is an extrinsic semiconductor. c. What are impurities used for in semiconductors. d. What is a donor impurity. e. What does it mean to dope a semiconductor. f. What is an n-type semiconductor. g. What is an acceptor impurity. h. What is a p-type semiconductor. i. What is the equation for the intrinsic carrier concentration and what does it mean? j. What is the concentration of electronics in a semiconductor doped with a donor impurity? k. What is the concentration of electronics in a semiconductor doped with an acceptor impurity?
