1. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Lecture 24 Basic Diode Concepts

2. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Diodes 1. Understand diode operation and select diodes for various applications. 2. Analyze nonlinear circuits using the graphical load-line technique.

3. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. 3. Analyze and design simple voltage-regulator circuits. 4. Solve circuits using the ideal-diode model and piecewise-linear models. 5. Understand various rectifier and wave shaping circuits.

4. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Fluid Analogy

5. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Diode-Fluid Analogy Schematic diagram of a flapper valve

6. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Thermionic Diode

7. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Cat’s Whisker

8. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Galena (Sulphide Ore of Lead)

9. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Cat’s Whisker

10. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Semiconductor Diode

11. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. P-Type and N-Type Materials http://www.ineer.org/Events/ICEE1999/Proceedings/papers/334/334.htm

12. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. P-N Junction http://www.ineer.org/Events/ICEE1999/Proceedings/papers/334/334.htm

13. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Carrier Recombination http://www.ineer.org/Events/ICEE1999/Proceedings/papers/334/334.htm

14. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Depletion Layer http://www.ineer.org/Events/ICEE1999/Proceedings/papers/334/334.htm

15. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. I-V Characteristic “On” “Off” Reverse Breakdown Non-linear I-V Characteristic

16. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Shockley Equation n = Emission coefficient (1<n<2) k = 1.38 × 10 –23 J/K is Boltzmann’s constant and q = 1.60 × 10 –19 C is the magnitude of the electrical charge of an electron. At a temperature of 300 K, we have

17. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Shockley Equation

18. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Zener Diodes Diodes that are intended to operate in the breakdown region are called Zener diodes.

19. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Zener Diodes

20. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Load-Line Analysis of Diode Circuits Assume V SS and R are known. Find i D and v D

21. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Load-Line Analysis of Diode Circuits

22. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Load-Line Analysis of Diode Circuits

23. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Load-Line Analysis of Diode Circuits

24. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Ideal Diode Model The ideal diode acts as a short circuit for forward currents and as an open circuit with reverse voltage applied. i D > 0v D < 0  diode is in the “on” state v D < 0 I D = 0  diode is in the “off” state

25. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits 1. Assume a state for each diode, either on (i.e., a short circuit) or off (i.e., an open circuit). For n diodes there are 2 n possible combinations of diode states. 2. Analyze the circuit to determine the current through the diodes assumed to be on and the voltage across the diodes assumed to be off.

26. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. 3. Check to see if the result is consistent with the assumed state for each diode. Current must flow in the forward direction for diodes assumed to be on. Furthermore, the voltage across the diodes assumed to be off must be positive at the cathode (i.e., reverse bias). 4. If the results are consistent with the assumed states, the analysis is finished. Otherwise, return to step 1 and choose a different combination of diode states.

27. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits Assume D 1 off and D 2 on: v D1 = 7V D 1 would be on!

28. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits Assume D 1 off and D 2 off: v D1 = 10Vv D2 = 3V Both diodes should be on!

29. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits Assume D 1 on and D 2 on:

30. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits i1i1 i2i2 i3i3 Not consistent with direction of current through D 2 !

31. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits Assume D 1 on and D 2 off: i D1 =1mA 6V v D1 = -3V This works!

32. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits

33. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 1 on iDiD D 1 off D 1 would be on! This works!

34. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 2 onD 2 off iDiD Current is going the wrong way through the diode! V D consistent with D 2 off

35. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 3 on D 4 on D 3 on D 4 off D 3 off D 4 off D 3 off D 4 on

36. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 3 on D 4 on 6.67 mA -1.67 mA V

37. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 3 on D 4 off 10V 20V + - - +

38. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 3 off D 4 off Not consistent with 5 mA current source!

39. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Fourth Edition, by Allan R. Hambley, ©2008 Pearson Education, Inc. Assumed States for Analysis of Ideal-Diode Circuits D 3 off D 4 on V 5V 5mA + -