Diodes
Diodes are semiconductor devices that allow current to flow in only one direction and blocks the current in opposite direction. They have a positive terminal and a negative terminal. If the voltage on the positive terminal is higher than on the negative terminal then current flows through the diode. If the voltage is lower on the positive terminal than on the negative terminal then the current doesn’t flow. The negative leg of a diode is the one with the line closest to it. The negative terminal is called “cathode” and the postive terminal is called “anode”.
Diodes can be used as voltage regulators, tuning devices in rf tuned circuits, frequency multiplying devices in rf circuits, mixing devices in rf circuits, switching applications or can be used to make logic decisions in digital circuits. Usually when current is flowing through a diode, the voltage on the positive leg is 0.65 volts higher than on the negative leg.
Types of Diodes:
There are three types of diodes (without “photonic diode” types):
• Silicon Diodes
• Germanium Diodes
• Zener Diodes
Silicon diodes are the most common diodes and Tehy are made of small chip of silicon. This is mostly used as rectifiers in power supplies.
Germanium diodes are made of a small chip of germanium and these type of diodes handle very less power than silicon diodes. Germanium diodes are commonly used to demoduate radio signals.
Zener diodes have a specific reverse breakdown voltage. Zener diode is used as a voltage sensitive switch. It has an ability to maintain an constant voltage with a wide range of current. So Zener diodes are widely used to regulate the voltage across a circuit.