Electronic Circuits - Diode Applications

Electronic Circuits - ELEC 10004.2

• Course covers diode applications
• Students should also use recommended textbooks and supplementary materials for complete understanding
• PowerPoint presentations are guides for class delivery
• Content from presentations and other in-class materials, including board writing, are important parts of the course
• Avoid plagiarism and properly cite sources
• Refer to the student handbook for academic integrity policies and penalties

Unit 1: Diode Applications

• Diodes are formed by joining n-type and p-type semiconductors
• The border between the n-type and p-type is a PN junction
• A schematic symbol for a diode shows an anode and a cathode
• At the PN junction, conduction band electrons in the n-type material are attracted to valence band holes in the p-type material.
• Electron migration creates negative charge on the p-type side and positive charge on the n-type side of the junction
• The depletion region is an area near the junction with a lack of free carriers due to electron-hole recombination
• The barrier potential is the potential at the PN junction that prevents electron and hole movement across the junction
• Germanium diodes have a barrier potential of 0.3 volts at 25°C; silicon diodes have 0.7 volts
• A diode ideally conducts in only one direction

Unit Overview

• Learning outcomes include classifying various diode applications, understanding electronic circuits with semiconductor devices, and considering environmental impacts

• The recommended textbook is "Electronic Devices and Circuit Theory" by Robert Boylestad and Louis Nashelsky(11th ed.)

• Other online resources are also available

• Assessments include quizzes, and assessments

Academic Integrity Violation

• Submit only MS Word documents
• Do not share work with other students
• Do not reuse assessments in multiple submissions or inappropriate locations
• Do not copy content from other sources
• Do not use screenshots in place of copied content
• Avoid any tampering with documents
• Refer to the student handbook for detailed policies and penalties

Grading, Attendance, and Late Submissions

• Late submissions are subject to penalties outlined in the student handbook (clause 4.2)
• Attendance is also subject to penalties as per the student handbook (clause 5.7)
• Incorrectly marked attendance must be reported to the faculty within three days

Diodes

• A diode is a two-terminal device

Biasing Techniques of the Diode

• Biasing involves applying voltage to a circuit to control diode current
• Possible biasing scenarios include no bias, forward bias (voltage greater than 0V), and reverse bias (Voltage less than 0V)

Forward Bias Condition

• The battery voltage's direction drives holes and electrons towards the junction.
• A low battery, less than the barrier potential prevents current flow.
• High voltage, more than the barrier, creates continuous current flow.

Reverse Bias Condition

• Negative terminal attracts holes, and positive terminal attracts free electrons.
• This movement of holes away from and electrons away from the junction widens the depletion region
• The increased width of the depletion region increases barrier potential, making current flow very difficult.

Volt-Ampere (V-I) Characteristics of a PN Junction

• Shows the relationship between current and voltage across a PN junction at a given temperature
• Germanium (Ge) and Silicon (Si) have different characteristics

Diode Current Equation

• The equation describes the diode current (ID) as a function of reverse saturation current (Is), voltage (V), temperature (T), and the emission coefficient (η)

Problem

• A Ge diode has a current of 10mA at 0.2V forward bias at 293°K.
• Determine reverse saturation current and biasing voltages for 1mA currents

Diode Applications

• Rectifiers, clipper circuits, clamper circuits, and Zener diodes

Rectifiers and Power Supplies

• Rectifiers convert AC to DC

• Diodes are commonly used in rectification

• Half-wave and full-wave rectification are methods to achieve this

• There are several specific types of rectifiers, and their associated characteristics

Types of Rectifiers

• Half-wave rectification discards negative components of AC waveforms
• Full-wave rectification inverts the negative part of the signals

Rectification Circuit: Half-Wave

• Simplest kind of rectifier circuit
• Allows only one half of the AC signal to pass through to the load
• Converts AC to DC by utilizing electrons flow in one direction only

Rectification Circuit: Half-Wave

• The DC voltage is related to maximum input voltage (Vm) and Pi to a factor
• Efficiency of a half-wave rectifier is 40.6%

Rectification Circuit: Half-Wave

• Peak Inverse Voltage, or PIV is the maximum reverse voltage that the diode can withstand

• For most power applications half-wave rectification is insufficient because the waveform harmonic content is large and therefore difficult to filter. AC power supply only delivers power once every half-cycle.

Rectification Circuit: Full-Wave

• Center-tap full-wave rectifier
• Full-wave bridge rectifier

Rectification Circuit: Full-Wave

• The DC voltage for a full-wave rectifier circuit is related to the maximum input voltage and the Pi value
• Bridge rectifier PIV/PRV >= 2Vm .

Rectifier Comparisons

• Comparison of half-wave, full-wave, and bridge rectifier characteristics

Clipper Circuits

• Clippers are used to clip away specific portions of the input signal without distorting the remaining parts

Series Clipper - Example

• This section shows a calculation example of how to determine output waveform using a series clipper circuit

Parallel Clipper - Example

• This section shows a calculation example of how to determine output waveform using a parallel clipper circuit

Clamper Circuits

• Clamping circuits restore lost DC levels in signals

Clamper Circuit - Example

• Example calculation/graph demonstration of a clamping circuit

Zener Diode

• A zener diode allows current flow in both forward and reverse directions beyond a specific breakdown voltage (Vz)

Example

• Demonstrates the calculation process for finding the Zener voltage in a circuit given input voltage, resistance, and other component values
• This section shows a diode being removed and other values calculated. This circuit is then evaluated to determines if the zener diode is on or off

Formative Assessments

• Quiz is part of formative assessment

References

• Specific textbook titles, editions, and authors are listed for further reference

This quiz focuses on the essential concepts of diode applications covered in ELEC 10004.2. Students will explore the operation of diodes, the significance of PN junctions, and the principles of electron migration. Mastering these topics is crucial for understanding more advanced electronic circuits.