What are the common diodes?
1. Varactor diode
The varactor is a nonlinear capacitor made from the capacitance of PN junction with the external bias voltage. It is widely used in the circuit of parametric amplifier, electronic tuning and frequency doubler. Variable-capacitor diodes mainly highlight the nonlinear relationship between capacitance and voltage through a series of ways such as structure design and technology, and improve the Q value for application. The structure of the varactor diode is similar to the ordinary diode.
2. Step recovery diode
Step recovery diode is a special type of varactor diode, also called a charge storage diode, called a step tube.
It has a highly nonlinear reactance. Its application in frequency doubler is its unique feature. It can obtain high efficiency high frequency doubling by using the rich harmonics contained in the rapid mutation of its reverse current recovery. It is an excellent frequency doubling element in the field of microwave.
The characteristics of step tubes are based on the special distribution of impurities in PN junctions. Similar to varactor diodes, the circuit symbols of step transistors have the same DC voltage-ampere characteristics as those of ordinary PN structure step transistors.
The characteristic of the step tube is that when the diode in the conduction state is suddenly added to the reverse voltage, the instantaneous reverse current immediately reaches the maximum value of IR, and maintains a certain time, and then returns to zero immediately.
3. Bi-directional trigger diode
The bidirectional trigger diode is composed of three layers of silicon NPN, which is a symmetrical semiconductor pole tube device, which can be equivalent to a base open circuit, a collector and a emitter NPN type transistor.
When the input voltage is less than the turning voltage, the tube is not connected and the current is very small. Once the transmission voltage is equal to the turning voltage, the tube is connected and the current rises rapidly, showing the negative resistance characteristic.
Bi-directional trigger diode is simple in structure and low in price. It is often used to trigger bi-directional thyristor, and it can also form overvoltage protection circuit.
If you want to know more, our website has product specifications for the diodes, you can go to Allicdata Electronics to get more information.