p-n Junction Diode & Rectification

What is a p-n Junction Diode?

A p-n junction diode is a semiconductor device that allows current to flow in one direction. It is made by joining p-type and n-type semiconductors.

Forward and Reverse Biasing

• Forward Biasing: When the p-side is connected to the positive terminal and the n-side to the negative terminal of a battery, the diode conducts electricity.
• Reverse Biasing: When the p-side is connected to the negative terminal and the n-side to the positive terminal, the diode does not conduct electricity.

Voltage Characteristics

• In forward bias, the diode starts conducting when the applied voltage exceeds a certain threshold (typically 0.7V for silicon diodes).
• In reverse bias, a small leakage current flows until breakdown voltage is reached, beyond which the diode may get damaged.

Uses of Diodes

• Rectification: Converting alternating current (AC) to direct current (DC).
• Signal Demodulation: Extracting information from modulated signals.
• Voltage Regulation: Maintaining a constant voltage level.

Rectification

Rectification is the process of converting AC to DC. It is achieved using diodes in two main configurations:

Half-Wave Rectification

• Uses a single diode.
• Only allows one half of the AC waveform to pass through, blocking the other half.
• Results in a pulsating DC output.

Full-Wave Rectification

• Uses multiple diodes (usually four in a bridge configuration).
• Allows both halves of the AC waveform to be converted to DC.
• Results in a smoother DC output compared to half-wave rectification.