Diodes and Their Applications

1
Chapter 6

• Diodes and Their Applications

2
Objectives

• Describe how the properties of a semiconductor
  differ from those of a conductor and an
  insulator.
• Define donors and acceptors and discuss their
  functions in creating P-type material and N-type
  material.
• Discuss the basic properties of a PN-junction
  diode and sketch the form of the terminal
  characteristic curve.

3
Objectives

• Describe the ideal model and the constant voltage
  model for a junction diode and draw the
  equivalent circuit forms.
• Analyze simple circuit forms containing diodes
  and determine when a diode is forward biased or
  reverse biased.
• State the input-output properties of an ideal
  transformer in terms of the turns ratio.

4
Objectives

• Draw the schematic diagram of a half-wave
  rectifier and analyze its operation.
• Draw the schematic diagram of a full-wave
  rectifier with a center-tapped secondary and
  analyze its operation.
• Draw the schematic diagram of a full-wave bridge
  rectifier and analyze its operation.
• Describe the function of a rectifier filter and
  analyze the ripple level.

5
Objectives

• Define peak inverse voltage and determine its
  value for different rectifier circuits.
• Discuss the properties of different types of
  diodes.
• Draw the schematic diagram of a zener regulator
  circuit and analyze its operation.

6
6-1 Semiconductor Concepts

• Conductors, Insulators, and Semiconductors
• Electrons or Holes
• Doping and Impurities (Donors or Acceptors)
• P-type and N-type Material

7
6-2 Junction Diode

• Schematic Symbol
• Applications
• Terminal Characteristic

8
PN-junction diode and its schematic symbol.
9
Ideal resistance and its terminal characteristic.
10
Experiment used to determine semiconductor diode
terminal characteristic.
11
Form of the terminal characteristic of a
semiconductor diode.
12
6-3 Diode Circuit Models

• Ideal Diode Model
• Constant Voltage Model
• Other Models
• Which Model is Appropriate?
• Is a Diode Forward Biased or Reverse Biased?

13
Ideal diode model and terminal characteristic.
14
Constant voltage diode model and terminal
characteristic.
15
Circuit of Example 6-1.
16
Circuit of Example 6-2.
17
6-4 Diode Rectifier Circuits

• Why Convert AC to DC?
• Half-Wave Rectifier Circuit (Unfiltered)
• Full-Wave Rectifier Circuit (Unfiltered)
• Full-Wave Rectifier Bridge

18
A half-wave rectifier without filtering and the
waveforms.
19
Schematic diagram of an unfiltered full-wave
rectifier with a center-tapped transformer and
the waveforms.
20
Conduction models for full-wave rectifier with
center tap for alternate half-cycles.
21
Schematic diagram of an unfiltered full-wave
bridge rectifier circuit.
22
Conduction models for bridge rectifier for
alternate half-cycles.
23
6-5 Rectifier Circuits with Filtering

• Half-Wave Rectifier with Capacitor Filter
• Full-Wave Rectifiers with Capacitor Filter
• Ripple Analysis
• Reverse Diode Voltage
• More Complex Filter Circuits
• Power Supplies with a Voltage Regulator

24
Schematic diagram of a basic half-wave rectifier
circuit with transformer and capacitor filter.
25
Waveforms for half-wave rectifier with
transformer and filter.
26
Schematic diagram of a full-wave rectifier
circuit with transformer and capacitor filter.
27
Schematic diagram of a full-wave bridge rectifier
circuit with capacitor filter.
28
Waveforms for full-wave rectifier without and
with filter.
29
Schematic diagram of a rectifier circuit with
voltage regulator.
30
6-6 Survey of Other Diode Types

• Zener Diode
• Light Emitting Diode
• Photodiode
• Optocoupler
• Schottky Diode
• Varactor Diodes

31
Schematic symbols for various types of diodes.
32
6-7 Zener Regulator Circuits

• Qualitative Explanation

33
Typical zener regulator circuit.
34
Circuit of Example 6-8 with voltage and current
values labeled.
35
Circuit of Example 6-9 with voltage and current
values labeled.
36
Circuit of Example 6-10 with voltage and current
values labeled.