Diode

• A diode only allows current to flow in one direction.
• It has very high resistance in the reverse direction.

I-V characteristic of a diode

In the forward direction:

• The current is incredibly small until it reaches its activation voltage.
• That’s usually about 0.7 V for a silicon diode.
• After that, the current increases mostly proportionally with voltage. In the reverse direction:
• The current is almost zero, regardless of the voltage.
• This means the resistance is extremely high in the reverse direction.

Uses of diodes

• Diodes can be used to convert alternating current (AC) to direct current (DC).
• This is done in a component called a rectifier.
• The diode only allows the positive half-cycles of the AC to pass through.
• The negative half-cycles are blocked, resulting in a pulsating DC output.