Can anyone tell me and diodes ? What is a diode

A diode, a device with two electrodes that allows current to flow in a single direction, is used in many electronic components to apply its rectification function. Varactor diodes (VAFIC diodes) are used as electronic tunable capacitors.

The current directivity of most diodes is often referred to as "rectifying". The most common function of a diode is to allow only current to pass through a single direction (known as forward bias) and to block it in reverse direction (known as reverse bias). Therefore, the diode can be thought of as an electronic version of the check valve.

early vacuum electron diodes; It is an electronic device that is capable of conducting electric current in one direction. Inside the semiconductor diode, there is a PN junction with two lead terminals, and this electronic device has the conductivity of unidirectional current in the direction of the applied voltage. Generally speaking, a crystal diode is a p-n junction interface formed by the sintering of p-type semiconductors and n-type semiconductors.

A space charge layer is formed on both sides of its interface, which constitutes a self-built electric field. When the applied voltage is equal to zero, the diffusion current caused by the concentration difference between the carriers on both sides of the p-n junction and the drift current caused by the self-created electric field are equal and are in an equilibrium state, which is also a diode characteristic under normal conditions.

Early diodes contained "whisker crystals ("cat's whisker"crystals)" and vacuum tubes (known in the UK as "thermionic valves"), most of today's most common diodes use semiconductor materials.

Nickname. Crystal diodes.

Function. rectification, flame retardant, etc.

Breakdown. When the applied reverse voltage exceeds a certain value, the reverse current suddenly increases, a phenomenon called electrical breakdown. The critical voltage that causes electrical breakdown is called the diode reverse breakdown voltage.

When the diode is electrocuted, it loses its unidirectional conductivity. If the diode does not overheat due to electrical breakdown, the unidirectional conductivity is not necessarily permanently destroyed, and its performance can still be restored after the applied voltage is removed, otherwise the diode is damaged. Therefore, the reverse voltage applied to the diode should be avoided when using it.

Diode is a kind of two-terminal device with unidirectional conduction, there are electronic diodes and crystal diodes, electronic diodes because of the heat loss of filament, the efficiency is lower than that of crystal diodes, so it is rarely seen now, and the more common and commonly used are crystal diodes. The unidirectional conductivity of the diode, in almost all electronic circuits, semiconductor diodes are used, it plays an important role in many circuits, it is one of the earliest semiconductor devices, and its applications are also very wide.

A diode is an electronic device made of semiconductor materials (silicon, selenium, germanium, etc.). It has unidirectional conductivity, i.e., the diode turns on when a forward voltage is applied to the diode anode. When a reverse voltage is applied to the anode and cathode, the diode is cut off.

Therefore, the conduction and cut-off of the diode are equivalent to the switching on and off.

Diodes are one of the earliest semiconductor devices and are used in a wide range of applications. Especially in various electronic circuits, diodes and resistors, capacitors, inductors and other components are reasonably connected to form circuits with different functions, which can realize a variety of functions such as alternating current rectification, modulation signal detection, limiting and clamping, and voltage stabilization of power supply voltage. Diodes can be found in common radio circuits or in other household appliances or industrial control circuits.

Structure: The diode is encapsulated by a PN junction with the corresponding electrode leads and tube shells.

Using different doping processes, p-type semiconductors and n-type semiconductors are fabricated on the same semiconductor (usually silicon or germanium) substrate through diffusion, and a space charge region is formed at their interface, which is called a pn junction.

The electrode that emerges from the p-region is called the anode, and the electrode that emerges from the n-region is called the cathode. Due to the unidirectional conductivity of the PN junction, the direction of current flow from the anode to the cathode when the diode is turned on is through the inside of the tube.

The main categories are: point contact diode, surface contact diode, planar diode, voltage regulator, photodiode, light-emitting diode.

Diodes are ubiquitous in electronic devices. According to the semiconductor material, diodes can be divided into germanium diodes and silicon diodes; According to the core structure, it can be divided into point contact diode, surface contact diode and planar diode; According to the application, it can be divided into TVS transient suppression diode, ESD diode, voltage regulator diode, rectifier diode, Schottky diode, fast recovery diode, ultrafast recovery diode and so on.

Types of diodes.

Due to the unidirectional conduction performance of the diode, it has rectification; Since its temperature coefficient is opposite to the resistance, it can be used to do bias (voltage); With his reverse breakdown performance, the voltage can be stabilized; His on-voltage drop can also be used in cascades of multi-stage amplifiers, as well as in other occasions.

The performance of the diode depends on the switching time, the on-voltage drop, the withstand voltage, etc.; Let's not talk about diodes with special properties.

What is a crystal diode.

1. Rectifier diode Using the unidirectional conductivity of the diode, the alternating current with alternating direction can be converted into pulsed direct current in a single direction. 2. The resistance of the switching element diode is very small under the action of forward voltage and is in the on-on state, which is equivalent to a switch-on; Under the action of the reverse voltage, the resistance is very large, and it is in a cut-off state, like an open switch. Using the switching characteristics of diodes, various logic circuits can be composed.

3. After the limiting element diode is turned on forward, its forward voltage drop basically remains unchanged (silicon tube, germanium tube. This feature can be used as a limiting element in the circuit to limit the signal amplitude within a certain range. 4. The relay diode plays a relay role in the inductance of the switching power supply and the inductive load such as the relay.

5. The detector diode plays the role of detector in the radio. 6. Varactor diode is used in the high-frequency head of the TV. 7. Display elements are used on VCD, ***, calculator and other displays.

8. The reverse breakdown voltage of the voltage regulator diode is constant and can be recovered after breakdown, and the voltage stabilization circuit can be realized by using this feature. The working principle of the diode in this section The diode physical crystal diode is a p-n junction formed by a p-type semiconductor and an n-type semiconductor, forming a space charge layer on both sides of its interface, and building a self-built electric field. In the absence of an applied voltage, the diffusion current caused by the difference in carrier concentration on both sides of the p-n junction and the drift current caused by the self-built electric field are equal.

When there is a forward voltage bias in the external area, the mutual suppression effect of the external electric field and the self-built electric field increases the diffusion current of the carriers and causes the forward current. When there is a reverse voltage bias in the outside world, the external electric field and the self-built electric field are further strengthened to form a reverse saturation current i0 that is independent of the reverse bias voltage value within a certain reverse voltage range. When the applied reverse voltage is high to a certain extent, the electric field strength in the charge layer of the p-n junction space reaches a critical value, resulting in the multiplication process of carriers, resulting in a large number of electron-hole pairs, and a large reverse breakdown current is generated, which is called the breakdown phenomenon of the diode.

The reverse breakdown of the p-n junction is divided into Zener breakdown and avalanche breakdown.

The function of the diode is to have a voltage stabilizing effect, when the current increases instantaneously, the diode can protect the current from passing through the load connected in parallel with the diode, and can play a role in protecting other parallel devices. The diode also has a clamping effect, which can maintain the voltage across the device connected to it within a range.

The diode can be thought of as an electronic check valve. In reality, however, diodes do not exhibit such perfect on/off directionality, but rather complex nonlinear electronic signatures that are determined by the specific type of diode technology.

In the parameters of the transistor VCBO VCO VCEO VEBO, the requirements of VEBO are the highest, the most commonly used 8050, the above three parameters are: 30V 25V 6V, so the voltage value of VEBO needs to be strictly controlled.

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A diode is a type of semiconductor material that has a positive and negative electrode and can conduct current in one direction.

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