- \n
- What is a Diode?<\/a>\n\n<\/li>\n
- Diode Symbol<\/a>\n\n<\/li>\n
- Diode Construction<\/a>\n\n<\/li>\n
- Types of Diodes<\/a>\n\n\n
- \nLight Emitting Diode<\/a>\n\n<\/li>\n
- Semiconductor Diode<\/a>\n\n<\/li>\n
- Transient-voltage-suppression Diode<\/a>\n\n<\/li>\n
- Tunnel Diode<\/a>\n\n<\/li>\n
- Varicap<\/a>\n\n<\/li>\n
- Zener Diode<\/a>\n\n<\/li>\n<\/ul>\n
- Characteristics of Diode<\/a>\n\n\n
- \nForward Bias Characteristic of Diode<\/a>\n\n<\/li>\n
- Reverse Bias Characteristic of Diode<\/a>\n\n<\/li>\n<\/ul>\n
- Diode Applications<\/a>\n\n\n
- \nRectifiers<\/a>\n\n<\/li>\n
- Reverse Current Protection<\/a>\n\n<\/li>\n
- Flyback Diodes and Voltage Spike Suppression<\/a>\n\n<\/li>\n<\/ul>\n
- FAQs:<\/a>\n\n\n
- \nAre Diodes AC or DC?<\/a>\n\n<\/li>\n
- What are the 3 main uses of diodes?<\/a>\n\n<\/li>\n
- Can a diode be used as a rectifier?<\/a>\n\n<\/li>\n
- Which is a common type of diode?<\/a>\n\n<\/li>\n<\/ul>\n
- Summary<\/a>\n<\/li><\/ul>\n\n
What is a Diode?<\/h2>\n\n\n
Diodes are most commonly used to ensure an electrical current passes in one direction. At the same time, they prevent it from flowing in the opposite direction.\u00a0<\/p>\n\n\n\n
Simply put, a diode is an electronic version of a check valve. Its ability to create a unidirectional current is called \u201crectification\u201d. <\/p>\n\n\n\n
This quality is used to change alternating current (known as AC) to direct current (or DC). <\/p>\n\n\n\n
When used in this manner, diodes are employed for tasks such as isolating modulation in radio devices.\u00a0<\/p>\n\n\n\n
Diodes also have more complex applications. They have nonlinear voltage qualities. <\/p>\n\n\n\n
Therefore, their forward-direction voltage decrease only fluctuates minimally with current. Any drop is more a result of temperature. <\/p>\n\n\n\n
Therefore, they are perfect for use in temperature monitors too.\u00a0<\/p>\n\n\n\n
Diodes have high resistance to a current that flows in the reverse direction. <\/p>\n\n\n\n
However, this resistance can fall rapidly when the reverse voltage achieves a particular value called \u201cbreakdown voltage<\/a>\u201d. <\/p>\n\n\n\n
In the case of semiconductor diodes, the current in the forward direction must reach a certain threshold before electricity is conducted.\u00a0<\/p>\n\n\n
Diode Symbol<\/h2>\n\n
\n<\/figure><\/div>\n\n
Diode Construction<\/h2>\n\n\n
Diodes are formed by connecting two P-Type and N-Type<\/a> semiconductors that are equally doped.\u00a0<\/p>\n\n\n\n
After they are joined together, the P-Type features extra holes and takes on a positive charge. Because of this, the N-Type then has an excess of electrons. <\/p>\n\n\n\n
At their connection point, the P-Type holes attract the electrons from the N-Type. The electrons then move across into the holes within the P-Type. <\/p>\n\n\n\n
Subsequently, this creates a flow of current in one direction.<\/p>\n\n\n
Types of Diodes<\/h2>\n\n\n
![\"Types](\"https:\/\/yourpcb.com\/wp-content\/uploads\/2023\/03\/1-48.jpg\")
<\/figure>\n\n\n\nCaption: Types of diode and radio elements<\/p>\n\n\n\n
There are several types of diode, let\u2019s take a look at some of the most common types in more detail:<\/p>\n\n\n
Light Emitting Diode<\/h3>\n\n\n
![\"light](\"https:\/\/yourpcb.com\/wp-content\/uploads\/2023\/03\/2-50.jpg\")
<\/figure>\n\n\n\nCaption: light emitting diode<\/p>\n\n\n\n
Light-emitting diodes are formed from a semiconductor with a direct band-gap, usually gallium arsenide.\u00a0<\/p>\n\n\n\n
This junction is then crossed by charge carriers that emit photons as they connect to the other side. As a result, light is produced. <\/p>\n\n\n\n
The type of light, whether it\u2019s infrared or ultraviolet, is dependent on the type of material used.\u00a0<\/p>\n\n\n\n
Original LEDs had a red or yellow color. However, new diodes with a higher frequency have been developed. <\/p>\n\n\n\n
All types of LED emit narrow spectrum light, and with different coatings and combinations, they can make a range of LED colors.\u00a0<\/p>\n\n\n
Semiconductor Diode<\/h3>\n\n\n
Semiconductor diodes are by far the most common type of diode. They are made from crystalline semiconductor material. <\/p>\n\n\n\n
This material has a P-N junction attached to two separate electric terminals. In addition, the current-to-voltage characteristic is exponential. <\/p>\n\n\n\n
This type of diode was the original semiconductor to be used in electronic products.\u00a0<\/p>\n\n\n
Transient-voltage-suppression Diode<\/h3>\n\n\n
This type of diode is specifically designed to shield other semiconductors against high-voltages. <\/p>\n\n\n\n
Transient voltage suppression diodes have much bigger cross-sectional\u00a0 P-N junctions than average diodes. <\/p>\n\n\n\n
Therefore, this enables them to conduct powerful currents without suffering damage.\u00a0\u00a0<\/p>\n\n\n
Tunnel Diode<\/h3>\n\n\n
Tunnel diodes are able to show negative resistance as a result of quantum tunneling. This enables them to amplify signals. <\/p>\n\n\n\n
They work incredibly fast, thanks to their very high carrier concentration. They can be used in high temperature, radiation, or magnetic field settings.<\/p>\n\n\n\n
Therefore, they are frequently used in space technology.\u00a0<\/p>\n\n\n
Varicap<\/h3>\n\n\n
Varicap diodes are great voltage-controlled capacitors. Thus, they are critical in FLL (frequency-locked loop) and PLL (phase-locked loop) circuits, enabling tuning circuits to rapidly lock to a frequency. They also facilitated the early tuning of radio equipment.\u00a0<\/p>\n\n\n
Zener Diode<\/h3>\n\n\n
![\"zener](\"https:\/\/yourpcb.com\/wp-content\/uploads\/2023\/03\/3-47.jpg\")
<\/figure>\n\n\n\nCaption: Zener diode<\/p>\n\n\n\n
Zener diodes are semiconductor device made of silicon that allows a current flow in either direction. <\/p>\n\n\n\n
This type of diode has a specialized P-N junction that is heavily doped. This allows it to carry current in reverse when a certain voltage level is achieved. <\/p>\n\n\n\n
The voltage drop across this type of diode stays consistent. Therefore, it is often used for voltage regulation.\u00a0\u00a0<\/p>\n\n\n
Characteristics of Diode<\/h2>\n\n\n
Diodes must block currents that flow in a reverse direction or behave as a short circuit if the current flow is in a forward direction. <\/p>\n\n\n\n
However, the real-life behavior of diodes is not always as simple as this.\u00a0<\/p>\n\n\n\n
Diodes will consume some power as they direct and conduct a forward-moving current and don\u2019t prevent all reverse-traveling currents.\u00a0<\/p>\n\n\n\n
Let\u2019s look at some interesting characteristics of diodes and how they work in reality.\u00a0<\/p>\n\n\n
Forward Bias Characteristic of Diode<\/h3>\n\n\n
Forward bias describes when the P terminal has a higher positive charge than the N terminal. <\/p>\n\n\n\n
In this case, the positive terminal of its battery acts as a repellent to holes or majority carriers in the P region. <\/p>\n\n\n\n
It also repels electrons from the negative terminal in the N region – shunting them in the direction of the junction.\u00a0<\/p>\n\n\n\n
This leads to an increase in the number of charge carriers in the junction region. Electrons’ recombination occurs, and the depletion width in this region reduces. <\/p>\n\n\n\n
Consequently, there is an exponential increase in the current.\u00a0<\/p>\n\n\n
Reverse Bias Characteristic of Diode<\/h3>\n\n\n
Reverse bias is when a P terminal connects to the negative terminal of a battery, and an N terminal connects to the positive terminal of a battery. <\/p>\n\n\n\n
As a result, the N terminal has a greater positive charge than the P terminal.\u00a0\u00a0<\/p>\n\n\n\n
The result is that the negative battery terminal attracts the holes, majority carriers from the P region, and the positive battery terminal gains electrons from the N terminal and attracts them away from the junction. <\/p>\n\n\n\n
This activity leads to a reduction in charge concentration and a width depletion around the junction.<\/p>\n\n\n
Diode Applications<\/h2>\n\n\n
Diodes are simple electrical devices used in a vast range of applications. They are found in almost every type of electrical circuit. Therefore, their importance shouldn\u2019t be underestimated!<\/p>\n\n\n\n
In this section, we look at some of their most common uses.\u00a0<\/p>\n\n\n
Rectifiers<\/h3>\n\n\n
Rectif<\/a>iers are circuits that convert AC (alternating current) into DC (direct current). This currency conversion is required for all manner of common electronics. <\/p>\n\n\n\n
Alternating current signals flow from your household power outlets. However, it is the direct current that powers most electrical devices. <\/p>\n\n\n\n
Do you see the problem here?<\/p>\n\n\n\n
AC behaves exactly as its name suggests – it alternates! It switches backward and forwards between positive and negative. <\/p>\n\n\n\n
On the other hand, DC moves in just one direction.\u00a0<\/p>\n\n\n\n
It must be prevented from flowing backward to convert AC and make it move in one direction. This is what diodes are for!<\/p>\n\n\n
Reverse Current Protection<\/h3>\n\n\n
Sometimes you must prevent a current from going backward to protect a circuit. <\/p>\n\n\n\n
If a diode is used on the positive side of a circuit, it will stop the current from moving in reverse. This ensures that the power can only flow in a positive direction and provides positive voltage within the circuit.\u00a0<\/p>\n\n\n
Flyback Diodes and Voltage Spike Suppression<\/h3>\n\n\n
![\"surge](\"https:\/\/yourpcb.com\/wp-content\/uploads\/2023\/03\/4-43.jpg\")
<\/figure>\n\n\n\nCaption: surge protector burnt<\/p>\n\n\n\n
Diodes are commonly used to shield against damage caused by sudden voltage surges. TVS (transient voltage suppression<\/a>) diodes, as explained above, are a special type of diode. <\/p>\n\n\n\n
They are rated to withstand incredibly high voltages, so they can \u201cpush\u201d it back if a surge occurs. <\/p>\n\n\n\n
In extreme cases, a TVS diode will absorb the excess voltage, thus protecting equipment further down the line.\u00a0<\/p>\n\n\n
FAQs:<\/h2>\n\n
Are Diodes AC or DC?<\/h3>\n\n\n
Diodes only work in DC (direct current) as they are unidirectional electrical devices. Therefore, they are designed to only allow current to move in one direction. <\/p>\n\n\n
What are the 3 main uses of diodes?<\/h3>\n\n\n
The three main uses of diodes are rectifiers for reverse current protection and voltage spike suppression. <\/p>\n\n\n
Can a diode be used as a rectifier?<\/h3>\n\n\n
Yes. Diodes are commonly used as rectifiers. <\/p>\n\n\n
Which is a common type of diode?<\/h3>\n\n\n
The most commonly used type of diode is a rectifier diode. This diode has a large P-N junction area and converts AC to DC for most household electronics. <\/p>\n\n\n
Summary<\/h2>\n\n\n
![\"AC](\"https:\/\/yourpcb.com\/wp-content\/uploads\/2023\/03\/5-16.jpg\")
<\/figure>\n\n\n\nCaption: AC to DC<\/p>\n\n\n\n
Diodes are relatively simple devices but incredibly useful in our daily lives. <\/p>\n\n\n\n
- What are the 3 main uses of diodes?<\/a>\n\n<\/li>\n
- Reverse Current Protection<\/a>\n\n<\/li>\n
- Reverse Bias Characteristic of Diode<\/a>\n\n<\/li>\n<\/ul>\n
- Semiconductor Diode<\/a>\n\n<\/li>\n
- Diode Symbol<\/a>\n\n<\/li>\n