In this condition, the diode behaves as a close switch as it allows the current to flow. For the ideal diode, the on-state resistance is zero and It behaves as a pure conductor. In reverse bias, the N-type material or cathode is connected with a negative terminal of the battery. This type of connection is known as a reverse bias connection. In this condition, the voltage is gradually increased with the help of a variable resistor. But this voltage is not sufficient to cause the flow of current.
Because the junction created between P-type and N-type layer is in reverse bias and the depletion width is large in this condition.
Therefore, the rated voltage is not sufficient to create a movement of charge carrier. Hence, the current will not flow through the diode.
The curve obtains in this mode is OA. As shown in the graph, a very small amount of current will flow due to the minority charge carrier, this current is not sufficient to turn ON the diode. When the applied voltage is more than the reverse breakdown voltage, a large current will flow due to the avalanche breakdown.
This part is shown as AB in the graph. There are different types of diodes and we have explained each type of diode in very detail in the previous post. You may refer to the 24 types of diodes article. There are some advantages of PN junction diodes over vacuum diodes as follow. Diodes are used in various applications in power electronics. The diode is a unidirectional two-terminal device that only allows flowing the current in one direction and blocks the current in another direction.
Due to this characteristic, the diode is used in the application like;. There are many other types of diodes are available that is made for the several types of diode like;.
Related Posts:. I have a query regarding the reverse biased capacitance of a diode with temperature change. I understand that in reverse biased a diode will look like a capacitor.
The value will be based on the type of diode and the reverse voltage applied. I get all that but for a given reverse voltage and a given diode what happens to the capacitance with temperature change?
For instance how does a 1N diode capacitance with a given set reverse voltage vary with temperature changes?. I have seen nothing noted in any data sheet so far? Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email. Table of Contents. Electrical Technology 1 7 minutes read. Show More. Related Articles. One Comment. Leave a Reply Cancel reply Your email address will not be published. Check Also. Difference Between Photodiode and Phototransistor.
Close Search for. Adblock Detected Our website is made possible by displaying online advertisements to our visitors. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content. Dhirendra Yadav. No Comments. What is Tunnel diode? Circuit symbol: The tunnel diode is a two terminal device with p-type semiconductor acting as anode and n-type semiconductor as cathode.
Tunnel diode working principle: According to the classical laws of physics, a charged particle sin order to cross an energy barrier should possess energy at least equal to the energy barrier. V-I characteristics of Tunnel diode: The IV characteristics of the tunnel diode is shown below For small forward voltages owing to high carrier concentrations in tunnel diode and due to tunneling effect the forward resistance will be very small.
Peak voltage, Peak current of tunnel diode: The peak voltage of a tunnel diode can be found as follows: At peak voltage current through the tunnel diode is maximum. Low cost Low noise Environmental immunity Low power dissipation Simplicity in fabrication Longevity Disadvantages of tunnel diode: Low output voltage swing Because it is a two terminal device, there is no isolation between input and output.
Applications of tunnel diode: Some of the applications of Tunnel diode are Tunnel diodes are used as very high-speed switches. Used as high-frequency micro wave oscillator. Leave a Reply Cancel reply Your email address will not be published. Related Posts. The rectifier circuit used in the switching regulator power supply and the rectifier diode used in the pulse rectifier circuit should use a rectifier diode or a fast recovery diode with a higher operating frequency and a shorter reverse recovery time.
The detector diode is a device that detects a low-frequency signal superimposed on a high-frequency carrier and has high detection efficiency and good frequency characteristics. The detection diode requires a small forward voltage drop, high detection efficiency, small junction capacitance, and good frequency characteristics, and its shape is generally EA glass package structure. The general detection diode adopts a point contact type structure of tantalum material.
When selecting a detector diode, the detector diode with high operating frequency, small reverse current, and sufficient forward current should be selected according to the specific requirements of the circuit. Since the semiconductor diode has a positive bias, the on-resistance is small.
When the reverse bias is applied, the cutoff is applied. The off-resistance is large, and the unidirectional conduction characteristic of the semiconductor diode in the storage switching circuit can turn on and off the current, so the semiconductor diode used for this purpose is called a switching diode. Switch diodes are mainly used in household appliances and electronic equipment such as tape recorders, televisions, and DVD players, such as switching circuits, detection circuits, and high-frequency pulse rectifier circuits.
The 2AK series of common switch diodes can be selected for the medium-speed switching and detection circuits. The specific model of the switching diode should be selected according to the main parameters of the application circuit such as forward current, high reverse voltage, reverse recovery time, etc.
The Zener diode is characterized by the fact that the voltage of the PN junction reversely changes without changing with the current to achieve the purpose of voltage regulation.
Because it can regulate the voltage in the circuit, it is called a Zener diode referred to as a voltage regulator. The Zener diode is classified according to the breakdown voltage, and its voltage regulation value is the breakdown voltage value.
The Zener diode is mainly used as a voltage regulator or voltage reference component. Zener diodes can be connected in series to obtain a higher voltage regulation value. The selected Zener diode should meet the requirements of the main parameters in the application circuit. The stable voltage value of the Zener diode should be the same as the reference voltage value of the application circuit. The Fast Recovery Diode is a new type of semiconductor diode. This diode has good switching characteristics and short reverse recovery time and is commonly used as a rectifier diode in high-frequency switching power supplies.
The fast recovery diode has the characteristics of short recovery time and is suitable for high frequency such as TV line frequency rectification.
The fast recovery diode has an important parameter that determines its performance-reverse recovery time. The reverse recovery time is defined as the diode falling from the output pulse to the zero lines, and transitioning from the forward conducting state to the off state.
Ultra-fast recovery diodes SRDs are developed based on fast recovery diodes, the main difference is that the reverse recovery time is smaller. The reverse recovery time of a normal fast recovery diode is several hundred nanoseconds, and the reverse recovery time of an ultra-fast recovery diode SRD is typically several tens of nanoseconds. The smaller the value, the higher the operating frequency of the fast recovery diode. When the operating frequency is in the range of tens to hundreds of k Hz, the change of the forward and reverse voltage of the ordinary rectifier diode is slower than the recovery time, and the ordinary rectifier diode cannot normally conduct unidirectional conduction and rectification.
At this time, it is necessary to use a fast recovery rectifier diode to be competent. Therefore, the rectifier diodes powered by a switching power supply such as a color TV are usually fast recovery diodes and cannot be replaced by ordinary rectifier diodes. Otherwise, the device may not work properly. It is a low-power, high-current, ultra-high-speed semiconductor device produced in recent years.
The reverse recovery time is extremely short can be as small as a few nanoseconds , the forward voltage drop is only about 0. These excellent characteristics are unmatched by fast recovery diodes. A Schottky diode is a metal-semiconductor device in which a noble metal gold, silver, aluminum, platinum, or the like is used as a positive electrode, and an N-type semiconductor is used as a negative electrode, and a barrier formed on the contact surface thereof has a rectifying property.
Schottky diodes are commonly used in high frequency, high current, low voltage rectifier circuits. The transient voltage suppression diode is abbreviated as TVP tube transient-voltage-suppressor. It is a semiconductor device developed on the basis of the process of the Zener diode and is mainly used in a fast overvoltage protection circuit for voltage.
It can be widely used in computers, electronic instruments, communication equipment, household appliances, and onboard or marine and automotive electronic equipment for field operations, and can be used as a protection element for over-voltage shock caused by human operation or an electric shock to equipment.
Transient voltage suppression diodes can be classified into four categories according to their peak pulse power: 50 w, W, W, w. Each class is divided into several types according to its nominal voltage.
When the voltage at both ends is higher than the rated value, the transient voltage suppression diode will turn on instantaneously, and the resistance at both ends will change from high resistance to low resistance at a very high speed, thereby absorbing a very large current and the voltage across the tube.
Clamp at a predetermined value. The English abbreviation for the light-emitting diode is LED , which is a device made of semiconductor materials such as gallium phosphide or phosphorus gallium arsenide, which can directly convert electrical energy into light energy. In addition to the unidirectional conduction characteristics of conventional diodes, LEDs can convert electrical energy into light energy. When a forward voltage is applied to the LED, it is also in a conductive state.
When the forward current flows through the mold, the LED emits light, which converts electrical energy into light energy. The color of the light-emitting diode is mainly determined by the material of the tube and the type of impurities. At present, the common LED light-emitting colors are mainly blue, green, yellow, red, orange, white, and so on. Among them, white LED is a new type of product, mainly used in mobile phone backlights, LCD backlights, lighting and other fields.
The operating current of the LED is usually 2 to 25 mA. The operating voltage ie, forward voltage drop varies from material to material: normal green, yellow, red, and orange light-emitting diodes operate at approximately 2V; white LEDs typically operate at voltages greater than 2. The working current of the LED should not exceed the rated value too high, otherwise, there is a danger of burning.
Therefore, a resistor R is usually connected in series in the LED circuit as a current-limiting resistor. The avalanche diode is a microwave power device developed based on the Zener process technology, which can generate high-frequency oscillation under the action of an applied voltage. The avalanche diode uses avalanche breakdown to inject carriers into the crystal. Since it takes a certain time for the carrier to pass through the semiconductor wafer, its current lags behind the voltage, resulting in a delay time.
If the passage time is properly controlled, the current is a negative resistance effect that occurs in the voltage relationship, leading to high-frequency oscillations.
It is commonly used in microwave communications, radar, tactical missiles, remote control, telemetry, instrumentation and other equipment. It is a silicon bidirectional voltage-triggered switching device.
When the voltage applied across the bidirectional trigger diode exceeds its breakdown voltage, both ends are turned on, and conduction will continue until the current is interrupted or dropped to a smallholding current of the device. Turn it off again. Bidirectional trigger diodes are commonly used in overvoltage protection circuits, phase shifting circuits, thyristor trigger circuits, and timing circuits. The varactor diode English name variable-Capacitance Diode, abbreviated as VCD is a special semiconductor device that uses reverse bias to change the PN junction capacitance.
A varactor diode is equivalent to a variable-capacity capacitor whose PN junction capacitance varies between the two electrodes and changes with the magnitude of the reverse voltage applied to the varactor diode. When the reverse voltage applied to the varactor increases, the capacity of the varactor decreases. Because varactors have this characteristic, they are mainly used in electrical tuning circuits such as high-frequency heads of color TVs , as an automatic trimming capacitor that can be controlled by voltage.
When selecting a varactor, it should be considered whether its operating frequency, high reverse operating voltage, large forward current and zero-bias junction capacitance meet the requirements of the application circuit.
The junction capacitance should be changed greatly, high Q value, reverse A varactor diode with a small leakage current. The crystal diode is commonly used in the circuit as a VD plus a digital representation, such as VD5 represents a diode numbered 5.
The identification of the diode is simple: the negative pole of the low-power diode is usually marked with a color ring on the surface; some diodes also use the "P" and "N" symbols to determine the polarity of the diode, "P" for the positive pole and "N" for the negative pole.
Metal-encapsulated diodes usually have a diode symbol printed on the surface with the same polarity; LEDs usually use the length of the pins to identify the positive and negative poles, the long legs are positive, and the short legs are negative.
The surface of the rectifier bridge is usually marked with the internal circuit structure or the name of the AC input and the DC output. Due to the variety of shapes of the chip diodes, the polarity is also marked by a variety of methods: in the leaded chip diode, the end of the tube with a white color ring is the negative electrode; in the chip diode with lead and colorless ring, the longer end of the lead wire is the positive electrode; in the leadless chip diode, the end of the ribbon or the notched end is the negative electrode.
When using an analog multimeter to test the diode, one end of the black pen with a smaller value is the positive pole, and the end connected to the red test pen is the negative pole. If the forward resistance and reverse resistance are infinite, the diode is open; if the forward resistance and reverse resistance are both 0, the diode is short-circuited.
Under normal conditions, the forward resistance of a germanium diode is about 1. When measuring a diode with a digital multimeter, connect the red pen to the anode of the diode and the black test lead to the cathode of the diode. The measured resistance is the forward conduction resistance of the diode, just like the pointer of a pointer multimeter.
It is more convenient to use the diode block detection diode of the digital multimeter: put the digital multimeter in the diode block, connect the negative pole of the diode to the black multimeter of the digital multimeter, and connect the positive pole of the digital multimeter to the red test lead. The forward voltage drop value of the diode. Diodes of different materials have different forward voltage drop values: 0.
At this time, the meter can be re-tested. What is a diode? A diode is reverse biased when it acts as an insulator and is forward biased when it allows current to flow.
A diode has two terminals, the anode and the cathode. What is a diode used for? Main functions. The most common function of a diode is to allow an electric current to pass in one direction called the diode's forward direction , while blocking it in the opposite direction the reverse direction.
As such, the diode can be viewed as an electronic version of a check valve. What is diode in basic electronics? A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction, but severely restricts current from flowing in the opposite direction.
What are the three main types of diodes? Types of diode Backward diode: This type of diode is sometimes also called the back diode. Gunn Diode: Although not a diode in the form of a PN junction, this type of diode is a semiconductor device that has two terminals. What is diode equation? What is the symbol of diode? The basic schematic symbol for a diode looks like an arrow head that points in the direction of conventional current flow from its Anode A terminal to its Cathode K terminal.
The schematic symbol of a diode also shows that if forward-biased, current will flow through the direction of the arrow. What is diode characteristics? The area surrounded by the orange dashed line in the diagram on the right indicates the usable area of rectifying diodes. What is ideal diode model? An ideal diode is one kind of an electrical component that performs like an ideal conductor when voltage is applied in forward bias and like an ideal insulator when the voltage is applied in reverse bias.
What are diode parameters? Peak Inverse Voltage, PIV: This diode characteristics is the maximum voltage a diode can withstand in the reverse direction. This voltage must not be exceeded otherwise the device may fail. The diode can withstand a reverse voltage up to a certain point, and then it will breakdown. How do you read a diode value? Diode Mode Testing Procedure Connect the red probe to the anode and black probe to the cathode. This means diode is forward-biased.
Observe the reading on meter display. If the displayed voltage value is in between 0. The Basic Introduction to Light-emitting Diode. Apogeeweb 15 Jun I IntroductionThe light-emitting diode is a commonly used light-emitting device, which emits energy through the recombination of electrons and holes.
It is widely used in the field of lighting. Continue reading ». Apogeeweb 26 Jul Apogeeweb 15 Nov Introduction Diodes are widely used in electronics, such as rectification in power supply, as detection and mixing, etc. Light-emitting Diode Basics Tutorial. Apogeeweb 21 Jun Diode Physical Maps and Symbols. Apogeeweb 28 Feb Warm hints: This article contains about words and reading time is about 15 mins.
IntroductionAmong the electronic components, a diode is a device having two electrodes, which only allows current Apogeeweb 28 Jul IntroductionIn electronics, the diode has the unique characteristic of unidirectional conduction.
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