The semiconductor diode is place an important part in many electronic circuit designs. It have a variety of package, SMD diodes, normal wire leaded diodes, and power diodes as well.
Different types of diode have their features and performance although most of them are based on the same structure of PN-junction. Diodes are used in a variety of areas, such as using as power diodes for power rectification, for simple signal rectification, signal detection, RF design, laser light generation, light detection, and so on.
With the wide application of Surface Mount Technology in the PCB assembly industry, the package of SMD diodes is more and more usual. Especially the SOT-23 package, it is used for many small discrete diodes. Only two of the three pins available are used and it enables the diodes to be correctly orientated.
Diodes come in all shapes and sizes. There are leaded package, glass encapsulated diodes, and plastic package. It can be vary in size based on the power dissipation required. The SMD diode is too compact to include its full part number, so that it is used a short form number to distinguish.
Each type of diodes has different properties that suitable for a variety of electronic circuit designs, RF designs, and general digital design.
Rectifier Diode
The current directionality of the diode —— Rectification, which converts AC power into DC power. The performance is relatively stable, which makes it enable to withstand larger forward current and higher reverse voltage. Due to the large junction capacitance, it is not suitable to the high-frequency circuits, so that it cannot be used as a detector tube. There are metal and plastic packages.
Detector Diode
The detector diode is used to detect the low-frequency signal superimposed on the high-frequency carrier. It has high detection efficiency and good frequency characteristics. Most features glass package or ceramic shell package to obtain good high frequency characteristics.
Switching diode
Switching diodes are a type of diode specially designed for "on" and "off" on the circuit. It takes fewer time to change from on to off than that of ordinary diodes. The features of switching diode are fast switching speed, small size, long life and high reliability. It is widely used in switching circuits, detection circuits, high frequency and pulse rectifier circuits and automatic control circuits of electronic equipment.
Zener diode
The Zener diode (voltage reference diode) is a very useful type of diode. It refers to the phenomenon that the current can be changed in a wide range while the voltage is basically unchanged by using the reverse breakdown state of the PN-junction, and is made to have a voltage stabilizing effect.
Varactor diode
The function of theVaractor diode is to use the principle of variable capacitance between PN junctions to make semiconductor devices, which are used as variable capacitors in circuits such as high-frequency tuning and communication.
Schottky diodes
Schottky diodes has a lower forward voltage drop than ordinary silicon PN-junction diodes. They are widely used as clamping diodes, and in RF designs, often as signal detectors. Besides, it is used as power diodes for rectification of AC power in power supplies and the like. The lower losses caused by the smaller drop are significant in improving the efficiency.
Damping diode
Damping diodes are similar to high-frequency, high-voltage rectifier diodes, which are characterized by lower voltage drop and higher operating frequency, and can withstand higher reverse breakdown voltage and higher peak current. Mainly used in TV sets.