The most important characteristics of the diode is conductive in one direction. In the circuit, current can only flow from the diode cathode, negative outflow. The following simple experiment illustrates the forward diode characteristics and
42 datasheet and reverse characteristics.
1) positive characteristics
in the electronic circuit, the diode cathode connected to the high potential side, the low potential side connected to the anode, the diode will turn this connection, known as forward bias. Have demonstrated that when both ends of the diode forward voltage is very small, still can not turn on the diode, the forward current flowing through the diode is very weak. Only when the forward voltage reaches the threshold voltage, the diode can be a real turn-on.
2) reverse characteristics
in the electronic circuit, the diode cathode connected to the low potential side, the negative pole in the high potential side. At this point, the diode is almost no current flowing through the diode is off. This connection, known as the reverse bias.
43. What is the diode works?
crystal diode is a P-type semiconductor and
42 price and the formation of N-type semiconductor PN junction, formed at both sides of the interface space charge layer, and
42 suppliers and has a self-built electric field. When there is no applied voltage, because the PN junction carrier concentration difference on both sides of the spread caused by electric current and self-induced drift currents equal in power balance.
when the outside world has a positive voltage bias, the external electric field and the mutual inhibition of the self-built electric field carrier diffusion current increases caused by the forward current.
when the outside world when the reverse bias voltage, external electric field and electric field to further strengthen the self, the formation of certain reverse bias voltage within the range of reverse voltage without reverse saturation current Fu.
44. diode types are there?
(1) in accordance with the semiconductor material used can be divided into a germanium diode (Ge tube) and silicon diode (Si tube).
(2) according to their different purposes, can be divided into the detector diode, rectifier diodes, Zener diodes, switching diodes.
(3) in accordance with the die structure can be divided into point contact diode, surface-contact diodes and planar diode. Point-contact diode is a very thin wire pressure in the smooth surface of the semiconductor wafer, through the pulse current, so that one end of wire with the chip firmly sintered together to form a "PN junction." As the point contact, allowing only by a small current (less than tens of mA) for high-frequency low-current circuit, such as radio detectors and so on. Surface-contact area of ??a large PN junction diode, allows a large current (several tens of safety to safety), mainly used to convert alternating current into direct current "rectification" circuit. Planar diode is a special silicon diodes, it is not only through the larger current, and reliable performance, used for switching, pulse and high frequency circuits.