Type of Diodes

Diodes can be classified by the functions of the circuit in which it is being used, or more commonly, by the shape that is demanded by the size of the products in which it will be mounted. The complicated point is that there is no direct relation between the two and you must keep them both in your mind at all times. However, you can think of the function as the base, and since this function can then be supported by many different shapes, it can then be further classified by those shapes.

Zener diode (constant voltage diode)
Since a Zener diode generates a constant voltage from the Zener effect that occurs when a reverse bias voltage is applied, it is also called a constant voltage diode. By using the resulting constant voltage, it can be used in constant voltage circuits and other circuits that require a reference voltage.

Schottky barrier diode
A Schottky barrier diode attaches a Schottky gate electrode directly to a n-type semiconductor and makes use of the fact that reverse bias voltages are prevented from causing current flow across the junction of the metal and semiconductor. Some are for high frequencies and some are for general rectification. Those for high frequencies are often used in high-speed switching for wave detectors and mixers in the UHF and microwave bands. Since the forward voltage is small and the reverse breakdown voltage cannot be made too high (currently, approx. 100 to 200 volts) compared to normal diodes for general rectification, Schottky barrier diodes for general rectification are used for the rectification of power supplies for low voltages and high currents, or power supply switching for the rectification of high frequencies with its small reverse recovery time.
Switching diode
By using the rectifying properties of the pn junction (the extreme difference in the forward and reverse bias resistances), these diodes are mainly used for switching the circuit on and off. Generally, when you speak of switching diodes, it includes Schottky barrier diodes and band switching diodes, but we at Rohm think of them as separate types. Switching diodes are the normal silicon small-signal switching diodes. They are used for demodulation, modulation, switching, mixing, and the like and make up approximately half of the total diodes produced in Japan. Rohm holds the largest share of this market.

Rectifier diodes
In general, these diodes are aimed at current rectification for currents of 1 ampere or more and are used in rectification circuits for power supplies. There are many types from low power to high power with a wide range of different packages. The most common type is the low power 1 ampere class that makes up approximately 70% of the rectifier diodes produced.

Band switching diodes
The band switching diode was developed as a general small signal diode for high frequency use. Since it is used for switching the frequency bands for high frequency tuners, the resistance at high frequencies is small and the capacitance between the electrodes is kept as small as possible.