Other Specialized Diodes

Varistor – Protecting Against Voltage Spikes

Overview:

Varistor Functionality:

Protection Mechanism:

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Current-Regulator Diodes – Ensuring Constant Current

Overview:

Schematic Symbol:

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Step-Recovery Diodes – The Snap Effect for Frequency Multiplication

Overview:

Schematic Symbol:

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Back Diodes – Efficient Rectification of Weak Signals

Overview:

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Tunnel Diodes – Mastering Negative Resistance

Overview:

Schematic Symbol:

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PIN Diodes – Variable Resistor for RF and Microwave Applications

Overview:

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Special-Purpose Devices

Device Key Idea Application
Zener diode Operates in breakdown region Voltage regulators
LED Emits noncoherent light DC or AC indicators, efficient light source
Seven-segment indicator Can display numbers Measuring instruments
Photodiode Light produces minority carriers Light detectors
Optocoupler Combines LED and photodiode Input/output isolators
Laser diode Emits coherent light CD/DVD players, broadband communications
Schottky diode Has no charge storage High-frequency rectifiers (300 MHz)
Varactor Acts like variable capacitance TV and receiver tuners
Varistor Breaks down both ways Line-spike protectors
Current-regulator diode Holds current constant Current regulators
Step-recovery diode Snaps off during reverse conduction Frequency multipliers
Back diode Conducts better in reverse Weak-signal rectifiers
Tunnel diode Has a negative-resistance region High-frequency oscillators
PIN diode Controlled resistance Microwave communications