Different types of diodes Flashcards
To be able to identify diodes and their purposes and differences
Definition and Symbol
A diode is a semiconductor device that allows current to flow in one direction only.
The symbol for a diode is an arrow pointing in the direction of conventional current flow.
Types of Diodes:
Rectifier Diodes: Convert AC to DC.
Light Emitting Diodes (LEDs): Emit light when current flows through them.
Zener Diodes: Designed to operate in the breakdown region, maintaining a nearly constant voltage.
Schottky Diodes: Known for their fast switching speed and low forward voltage drop.
Varactor Diodes: Used as voltage-controlled capacitors.
Forward Bias and Reverse Bias:
Forward Bias: Applying a voltage in the direction of the arrow on the diode symbol allows current to flow.
Reverse Bias: Applying a voltage in the opposite direction blocks current flow.
Forward Voltage Drop (Vf) value:
Diodes have a forward voltage drop when conducting, typically around 0.6 to 0.7 volts for silicon diodes
Reverse Breakdown Voltage (Vz):
The voltage at which a diode breaks down and allows reverse current flow. Zener diodes are designed for controlled breakdown.
I-V Characteristics:
The current-voltage (I-V) curve shows the relationship between current and voltage across a diode.
Equation used for diode current:
The Shockley diode equation relates the diode current to the voltage and temperature.
Applications:
Rectification: Converting AC to DC using rectifier diodes.
Clipping and Clamping: Altering waveforms using diodes.
Voltage Regulation: Zener diodes for stable voltage reference.
Light Emission: LEDs for indicators and displays.
Signal Demodulation: Used in communication systems
Temperature Effects:
Diode characteristics are temperature-dependent; temperature rise can affect their performance
Reverse Recovery Time:
In high-frequency applications, the time it takes for a diode to switch from conducting to non-conducting can be crucial.
