Diodes are of course different in size, power, voltage, current, and frequency are different. There are also many different classifications depending on function and function. These need to be checked for manual use. For simple comparison, you can see the package size. The larger the volume, the larger the current (the pressure is not necessarily), and the heat sink is larger than the heat sink.
1, detection diode
The main function of the detector diode is to detect low frequency signals in the high frequency signal. Their structure is point contact type, so their junction capacitance is small and the operating frequency is high. They are usually made of tantalum material. In principle, the modulation signal is taken from the input signal as a detection, and the magnitude of the rectified current (100 mA) is used as the boundary. The detection current is usually less than 100 mA.é”—Material point contact type, working frequency up to 400MHz, small forward voltage drop, small junction capacitance, high detection efficiency, good frequency characteristics, 2AP type. A diode for detection like a touch type can be used for circuits such as clipping, clipping, modulation, mixing, and switching, in addition to detection. There are also two diode assemblies with good characteristics for frequency modulation detection.
2. Rectifier Diode In principle, the DC output from the input AC is rectified. Taking the magnitude of the rectified current (100 mA) as the boundary, the output current is usually greater than 100 mA. The junction type, so the junction capacitance is large, generally below 3kHZ. The maximum reverse voltage is 25 volts to 3000 volts A to X total 22 gears. The classification is as follows: 1 silicon semiconductor rectifier diode 2CZ type, 2 silicon bridge rectifier QL type, 3 2CLG type used for TV high voltage silicon reactor working frequency nearly 100KHz.
3. After the limiting diode diode is forwarded, its forward voltage drop remains basically the same (0.7V for the silicon tube and 0.3V for the manifold). Using this feature, as a limiting component in the circuit, the signal amplitude can be limited to a certain range.
Most diodes can be used as limiting. There are also special limiting diodes like the protection meter and the high frequency Zener. In order to make these diodes have a particularly strong effect of limiting the sharp amplitude, diodes made of silicon material are usually used. There are also components sold: a number of necessary rectifier diodes are connected in series to form a single unit, depending on the voltage limit.
4. A modulation diode is usually referred to as a diode dedicated to ring modulation. It is a combination of four diodes with positive forward characteristics. Even though other varactors have modulation purposes, they are usually used directly as frequency modulation.
5. When the mixer diode uses the diode mixing method, Schottky type and point contact type diodes are often used in the frequency range of 500 to 10,000 Hz. 6. The amplifying diode is amplified by a diode, which is roughly amplified by a negative resistance device such as a tunnel diode and a body effect diode, and a parametric amplification by a varactor diode. Therefore, the diode for amplification generally refers to a tunnel diode, a body effect diode, and a varactor diode.
7. The switching diode diode has a small resistance under the action of the forward voltage, and is in a conducting state, which is equivalent to a switch that is turned on; under the action of the reverse voltage, the resistance is large and is in an off state, like a disconnected switch. Various switching logic circuits can be used to form various logic circuits.
There are logic operations used at low currents (10 mA) and magnetic core excitation switching diodes used at hundreds of milliamps. Low-current switching diodes are typically diode-type and key-type diodes, as well as silicon-diffused, mesa-type and planar diodes that can operate at high temperatures. The specialty of switching diodes is the fast switching speed. The Schottky diode has an extremely short switching time and is therefore an ideal switching diode. 2AK type point contact is used for medium speed switch circuit; 2CK type plane contact is used for high speed switch circuit; used for circuit of switching, limiting, clamping or detecting; Schottky (SBD) silicon high current switch, forward voltage drop Small, fast and efficient.
8. Varactor diodes are used for automatic frequency control (AFC) and for tuning small power diodes called varactor diodes. There are many other names in Japanese manufacturers. By applying a reverse voltage, the electrostatic capacitance of the PN junction is changed. Therefore, it is used for automatic frequency control, scanning oscillation, frequency modulation, and tuning. In general, although a diffusion diode using silicon is used, a specially fabricated diode such as an alloy diffusion type, an epitaxial type, or a double diffusion type can be used because these diodes have a particularly large rate of change in electrostatic capacitance with respect to voltage. The junction capacitance changes with the reverse voltage VR, instead of the variable capacitor, it is used as a tuning loop, an oscillating circuit, a phase-locked loop, and is commonly used for channel switching and tuning circuits of television tuner, mostly made of silicon material.
9. Frequency multiplication diodes have a frequency multiplication effect on the diodes, and there is a frequency multiplication by the varactor diodes and a frequency multiplication of the diodes depending on the step (ie, the jerk). The varactor diode for frequency multiplication is called a varactor. Although the varactor works the same as the varactor diode for automatic frequency control, the structure of the reactor can withstand high power. The step diode, which is also called a step recovery diode, has a short reverse recovery time trr when switching from on to off, and therefore its characteristic is that the transition time that rapidly becomes off is significantly short. If a sine wave is applied to the step diode, since the tt (transition time) is short, the output waveform is suddenly pinched off, so that many high-frequency harmonics can be generated.
10. Zener diode This tube is made by the reverse breakdown characteristics of the diode. The voltage across the circuit remains essentially constant, which acts to stabilize the voltage. It is a product that replaces the regulated electronic diode. It is made into a diffusion type or an alloy type of silicon. It is a diode whose reverse breakdown characteristic curve changes rapidly. Made as a control voltage and standard voltage. The terminal voltage (also known as Zener voltage) when the diode is working is from about 3V to 150V, and can be divided into many grades every 10%. In terms of power, there are also products ranging from 200mW to more than 100W. Working in the reverse breakdown state, made of silicon material, the dynamic resistance RZ is small, generally 2CW, 2CW56, etc.; the two complementary diodes are reversely connected in series to reduce the temperature coefficient is 2DW type.
The temperature coefficient of the Zener diode α: α represents the amount of change in the regulation value per 1 °C of temperature change. A tube with a stable voltage less than 4V has a negative temperature coefficient (which belongs to Zener breakdown), that is, a stable voltage value decreases when the temperature rises (temperature causes the valence electron to rise higher energy); a tube with a stable voltage greater than 7V has a positive temperature coefficient (belongs to Avalanche breakdown), that is, the steady voltage rises when the temperature rises (temperature causes the atomic amplitude to increase, hinders the movement of carriers); while the tube with a stable voltage between 4 and 7V, the temperature coefficient is very small, approximately zero. (Zina breakdown and avalanche breakdown).
11, PIN type diode (PIN Diode)
This is a crystal diode in which a layer of intrinsic semiconductor (or a semiconductor having a low concentration of impurities) is sandwiched between the P region and the N region. The I in the PIN is an English abbreviation of the meaning of "intrinsic". When its operating frequency exceeds 100MHz, due to the storage effect of minority carriers and the transit time effect in the "intrinsic" layer, its diode loses rectification and becomes an impedance element, and its impedance value varies with the bias voltage. And change. In the case of zero bias or DC reverse bias, the impedance of the "intrinsic" region is very high; when the DC is forward biased, the "intrinsic" region is presented due to the carrier being injected into the "intrinsic" region. Low impedance state. Therefore, the PIN diode can be used as a variable impedance element. It is often used in high frequency switching (ie microwave switching), phase shifting, modulation, limiting and other circuits.
12. Avalanche Diode
It is a transistor that can generate high frequency oscillations under the action of an applied voltage. The working principle of generating high-frequency oscillation is flawed: the carrier is injected into the crystal by avalanche breakdown. Since the carrier takes a certain time to pass the wafer, the current lags behind the voltage, and a delay time occurs. The more time, then, the negative resistance effect occurs in the relationship between current and voltage, resulting in high frequency oscillation. It is often used in oscillating circuits in the microwave field.
13. Jiangsui Diode (Tunnel Diode)
It is a crystal diode with a tunneling current as the main current component. The base materials are gallium arsenide and antimony. The N-type region of its P-type region is highly doped (i.e., highly concentrated). The tunneling current is produced by the quantum mechanical effects of these degenerate semiconductors. Tunneling has three conditions: 1 Fermi level is in the conduction band and full band; 2 space charge layer width must be very narrow (below 0.01 microns); holes in degenerate semiconductor P-type and N-type regions There is the possibility of overlapping with electrons at the same energy level. The Jiangsaki diode is a two-terminal active device. The main parameters are peak-to-valley current ratio IP/PV), where the subscript "P" stands for "peak" and the subscript "V" stands for "valley". The Jiangsaki diode can be used in low-noise high-frequency amplifiers and high-frequency oscillators (which operate at frequencies up to the millimeter band) and can also be used in high-speed switching circuits.
14, fast shutdown (step recovery) diode (Step Recovary Diode)
It is also a diode with a PN junction. Its structural characteristics are: there is a steep impurity distribution area at the boundary of the PN junction, thereby forming a "self-service electric field". Since the PN junction is under forward bias, it conducts with minority carriers and has a charge storage effect near the PN junction, so that its reverse current needs to undergo a "storage time" before it can be reduced to a minimum (reverse Saturation current value). The "self-service electric field" of the step recovery diode shortens the storage time, allows the reverse current to be quickly turned off, and produces rich harmonic components. A comb spectrum generation circuit can be designed using these harmonic components. Fast turn-off (step recovery) diodes are used in pulse and higher harmonic circuits.
15. Schottky Barrier Diode
It is a "metal-semiconductor junction" diode with Schottky characteristics. Its forward starting voltage is lower. In addition to the material, the metal layer may also be made of gold, molybdenum, nickel, titanium or the like. Its semiconductor material uses silicon or gallium arsenide, mostly N-type semiconductors. This device is electrically conductive by majority carriers, so its reverse saturation current is much larger than that of a minority carrier-conducting PN junction. Since the minority carrier in the Schottky diode has a very small memory effect, its frequency response is only limited by the RC time constant. Therefore, it is an ideal device for high frequency and fast switching. It operates at frequencies up to 100 GHz. Also, MIS (Metal-Insulator-Semiconductor) Schottky diodes can be used to fabricate solar cells or light-emitting diodes.
It can be used as a freewheeling diode, which acts as a freewheeling in the inductance of the switching power supply and inductive loads such as relays.
16. Damping diode damper diode is widely used in high-frequency voltage circuit, with high reverse working voltage and peak current, low forward voltage drop, high-frequency high-voltage rectifier diode, used in TV line scanning circuit for damping and boosting. For rectification. Commonly used damping diodes are 2CN1, 2CN2, BSBS44 and so on.
17. Transient voltage suppression diode
TVP tube, which provides fast overvoltage protection for the circuit, divided into bipolar and unipolar, classified by peak power (500W-5000W) and voltage (8.2V~200V).
18, double base diode (single junction transistor)
Two bases, one emitter three-terminal negative resistance device, are used for the relaxation oscillation circuit, and the timing voltage readout circuit has the advantages of easy frequency adjustment and good temperature stability.
19. The light-emitting diode is made of gallium phosphide or phosphorous arsenide material, and has a small volume and is driven to emit light in the forward direction. Low working voltage, small working current, uniform illumination, long life, red, yellow, green and blue monochromatic light. With the advancement of technology, white light-emitting diodes have recently been developed, forming an emerging industry of LED lighting. Also used on VCD, DVD, calculator and other displays.
20, silicon power switching diode silicon power switching diode has high-speed conduction and cut-off capability. It is mainly used for high-power switch or voltage regulator circuit, DC converter, high-speed motor speed regulation and high-frequency rectification and free-wheeling clamp pull in the drive circuit. It has the advantages of soft recovery characteristics and strong overload capability, and is widely used in computers. , radar power supply, stepper motor speed control and other aspects.
Shenzhen ChengRong Technology Co.,Ltd. , https://www.laptopstandsupplier.com