The document discusses the characteristics and functioning of p-n junction diodes, emphasizing their V-I characteristics, load lines, and operating points. It details how forward and reverse bias affects current flow, the role of load lines in circuit behavior, and how variations in load resistance and applied voltage influence the Q-point. Additionally, it explains the concepts of dynamic resistance and the operating characteristics of different types of diodes.

1. Dr. Susovan Mandal
Assistant Professor
Heritage Institute of Technology
Subject: Analog Circuit
(ECEN2101)
p-n Junction Diodes
Characteristics
1

2. Content
2
1.V-I Characteristics of Diode
2.Load-line and Operating Point

3. Different Types of Diodes
• https://www.e
lprocus.com/t
ypes-of-
diodes-and-
applications/

4. V-I Characteristics
• What is a
Rectifier
Diode?
• In this lecture
I will address
a rectifier
diode as
diode
• Diode
Symbol
• Physical
Diode
•A two terminal semiconductor device capable of
blocking flow of current in one direction while
allowing the flow in opposite direction is called an
ordinary diode or a rectifier diode or a p-n
junction diode.

5. V-I Characteristics

6. V-I Characteristics
• Simple diode
circuit
+ -

7. V-I Characteristics
+ -

8. V-I Characteristics
• Reverse Bias

9. V-I Characteristics

10. V-I Characteristics
• Dynamic
Resistance

11. V-I Characteristics
• Dynamic
Resistance

12. V-I Characteristics
• Dynamic
Resistance

13. V-I Characteristics
• Dynamic
Resistance

14. V-I Characteristics
• Dynamic
Resistance

15. V-I Characteristics

16. Load-line and Operating Point
16

17. Load-line for DC Bias

18. Load-line for DC Bias

19. Load-line for DC Bias

20. Load-line for DC Bias

21. Load-line for DC Bias

22. Load-line for DC Bias

23. Load-line for DC Bias
• Variation of
DC bias

24. Load-line for DC Bias
• Variation of
DC bias

25. Load-line for DC Bias
• Variation of
DC bias

26. Load-line for DC Bias

27. Load-line for AC Signal (Unbiased)

28. Load-line for AC Signal (Unbiased)

29. Load-line for AC Signal (Unbiased)
• For each new value of 𝑉
𝑠 and hence for 𝑉𝑖 an new load line and Q-point
appears.

30. Load-line for AC Signal (Unbiased)
• For each new value of 𝑉
𝑠 and hence for 𝑉𝑖 an new load line and Q-point
appears.

31. Load-line for AC Signal (Unbiased)
• For each new value of 𝑉
𝑠 and hence for 𝑉𝑖 an new load line and Q-point
appears.

32. Load-line for AC Signal (Unbiased)

33. Load-line for AC Signal (Unbiased)
• The infinite number of load-lines are covering the
gray-shaded region.

34. Load-line for AC Signal (Unbiased)
• The infinite number of load-lines are covering the
gray-shaded region.
• The locus of Q-point is through the intersections
of load-lines with the V-I characteristics of the
diode.

35. Load-line for AC Signal (Unbiased)
• Diode Load-
line animation

36. Load-line for AC Signal (Unbiased)

37. Load-line for AC Signal (Biased)

38. Load-line for AC Signal (Biased)
• Diode Load-
line animation

39. Load-line for AC Signal (Biased)

40. Lecture Summary
• Forward bias current (FBC) through a p-n junction diode increases
exponentially with the applied voltage. Thereby, current in a circuit
becomes unbounded if a diode is used alone in the circuit.
• Current in reverse bias is limited by the minority carriers.
• A load-line, appearing due to the presence of load, defines the current in
the circuit.
• A diode consumes very small voltage across it while delivering most of it to
the load.
• Q-point is defined as intersection of the load-line with the V-I characteristics
of the diode.
• Variations in load resistance vary the Q-point and thereby the circuit
current.
• Variations in the applied voltage also vary the Q-point and circuit current,
but the variations in the applied voltage and load resistance influence the
Q-point in directions.