Chapter 20 PN Junction Diodes Objectives After completing

Chapter 20 PN Junction Diodes Objectives  After completing

Chapter 20 PN Junction Diodes Objectives After completing this chapter, you will be able to:

Describe what a junction diode is and how it is made Define depletion region and barrier voltage Explain the difference between forward bias and reverse bias of a diode

Objectives (contd.) Draw and label the schematic symbol for a diode Describe three diode construction techniques Identify the most common diode packages Test diodes using an ohmmeter

PN Junctions Figure 20-1. Diode formed by joining P- and N-type material to form a PN junction. PN Junctions (contd.)

Figure 20-2. Barrier voltage as it exists across a PN junction. Diode Biasing Figure 20-3. PN junction diode with forward bias.

Diode Biasing (contd.) Figure 20-4. PN junction diode with reverse bias. Diode Characteristics

Figure 20-5. Diode schematic symbol. Diode Characteristics (contd.) Figure 20-6. Diode connected with forward bias.

Diode Characteristics (contd.) Figure 20-7. Diode connected with reverse bias. Diode Construction Techniques

Types of PN junctions Grown junction Alloyed junction Diffused junction Diode Construction Techniques

(contd.) Figure 20-8. Common diode packages. Diode Construction Techniques (contd.)

Figure 20-9. Packages for diodes. Testing PN Junction Diodes Ohmmeter Checks the forward-to-reverse-resistance

ratio of a diode Forward-biased diode Low resistance Reverse-biased diode

High resistance Summary A junction diode is created by joining N-type and P-type materials together The region near the junction is referred to

as the depletion region The charge at the junction creates a voltage called the barrier voltage A diode that is forward biased conducts current

Summary (contd.) A diode that is reverse biased conducts only a small leakage current Diodes can be constructed by the grown junction, alloyed junction, or diffused junction method

A diode is tested by comparing the forward to the reverse resistance with an ohmmeter

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