ECE 3040 Microelectronic Circuits Quiz 3, Quizzes of Electrical and Electronics Engineering

Download ECE 3040 Microelectronic Circuits Quiz 3 and more Quizzes Electrical and Electronics Engineering in PDF only on Docsity! ECE 3040 Microelectronic Circuits Quiz 3 June 2, 2004 Professor Leach Name Instructions. Print your name in the space above. The quiz is closed-book and closed-notes. The quiz consists of 2 problems. Honor Code Statement: I have neither given nor received help on this quiz. Initials 1. (a) What are the two diode reverse breakdown mechanisms called? Answer: Zener and avalanche. (b) Draw the symbol for a Zener diode. (See the notes or book) (c) What are the two charge storage mechanisms in a diode called? Which dominates for a forward biased diode and is it determined by a voltage or a current? Which dominates for a reverse biased diode and is it determined by a voltage or a current? Answer: Junction (or depletion) charge and diffusion charge. The diffusion charge dominates in a forward biased diode and is determined by the current. The junction (or depletion) charge dominates in a reverse biased diode and is determined by the voltage. (d) Describe the construction of a Schottky barrier diode and draw its symbol. Answer: It is a metal (aluminum) to semiconductor (n-type) junction. See notes or book for diagram. 2. A half-wave rectifier circuit is shown. It is given that vS (t) is a 60Hz sinusoidal voltage with an rms value of 24V. When the diode is forward biased, its voltage drop is VD0 = 0.6V. The circuit values are RL = 200Ω and C = 1000µF. (a) Calculate the peak load voltage. Answer: vL(peak) = 24 √ 2− 0.6 = 33.34V (b) Calculate the maximum reverse bias voltage across the diode. Answer: 33.341 − ¡−24√2¢ = 67.282V (c) The percent ripple is given by % ripple = [1− exp (−T/RLC)]×100%. When the diode is off, what is the lowest value that the load voltage can “droop” to before the diode conducts again? Answer: % ripple = · 1− exp µ −1 60× 200× 1000× 10−6 ¶¸ × 100% = 7.996% vAC = 33.341× 7.996 100 = 2.666V vdroop = 33.341− 2.666 = 30.675V 1