Ever wondered what makes your electronic devices tick? Diodes are the unsung heroes in many circuits. These small structures are important in regulating electric current in and out of circuits. Back to the diodes and let us look at some of the various categories of diodes available.
What Are Diodes?
Diodes are devices that permit electric current progression in a specific direction alone while preventing it in the opposite direction. They are sort of like one-way conduits for electricity. In addition to varying voltage systems, virtually every electronic device you possess, including smartphones, TVs, etc., contains diodes.
Types of Diodes
Now, let’s explore the different types of diodes you might encounter in your electronics journey:
Signal Diodes
Signal diodes are used in small-signal circuits and in many ways are the most commonly used diodes of all. That’s why you can come across them in circuits that process low-power signals. They perform well in applications such as guarding important segments against voltage spikes and conditioning shapes of signals in signal-manipulating circuits. Due to their small size, low forward voltage drop, and fast switching speed, they are suitable for such applications.
For example, a signal diode is used in an FM radio receiver to aid in heterodyning away the audio signal from the carrier.
Pros:
- Fast switching speed
- Low forward voltage drop.
- Small size is suitable for the compact design of electronic products and equipment.
Cons:
- Limited current handling capacity
- Does not well serve the high power needs.
- More sensitive to temperature changes than some other diode types
Rectifier Diodes
Rectifier diodes are famous for being the muscular type in the world of diodes. Their principal duty change the AC (Alternating Current) form of supply to the DC (Direct Current) form. These diodes are used mostly in power supply for electronics, chargers, and even welding equipment.
The use of rectifier diodes is unnoticed but when you insert your laptop charger into the wall outlet, they are at work. They transform the AC power that is available in your outlet to the DC power that your laptop requires. But these diodes allow higher current through them, forward voltage drop is higher, and switching times are relatively slow as compared to signal diodes.
Pros:
- Large AC current of handling
- Stable and dependable primarily for use in purposes involving the supply of power.
- It is also configurable in varying voltage and current capabilities.
Cons:
- Have a slightly higher forward voltage drop than in Schottky diodes
- It has a slower switching speed than signal or Schottky diodes
- This will produce more heat and in certain applications, more cooling may be necessary.
Zener Diodes
Zener diodes are the voltage regulators of the diode family. They are able to retain a constant voltage on their terminals in the condition that is known as reverse bias. This makes them suitable to be used in voltage control in power supplies and overvoltage protection circuits.
You may use a Zener diode to protect the costly microcontroller from unusual voltages that may result from switching surges or spikes. They come in a number of voltage classes so it is possible to get the one that suits a particular circuit. Their foremost strength is in their capacity to consistently deliver a particular voltage across a varying current, something that makes them very useful in most analog circuits.
Pros:
- Very suitable to be used for voltage regulation applications
- It is available in various voltages most of which are standard.
- Acceptable to varying voltage conditions because its ability to respond to this variation is well understood.
Cons:
- Very low current in the reverse breakdown mode at the present moment
- It means that the dependability of voltage can be influenced by temperature characteristics.
- Compared with some modern voltage regulator ICs, it is not so efficient.
Light-Emitting Diodes (LEDs)
LEDs are the bright stars of the diode world. Forward biasing makes them convert electrical energy into light. From the notification light on your phone to the headlights in your car, LEDs are everywhere in modern electronics.
These diodes come in several colors and in variable magnitude and as such they can be used for different purposes. Given that they use little power they have been used in modern lamps.
Pros:
- Energy efficiency is higher than that of normal light sources.
- Very long service life of the order of tens of thousands of hours.
- Comes in different colors and shades, all of which can be frosted to varying degrees.
Cons:
- Lacks the efficacy of traditional light bulbs in terms of light when compared to the closest comparable pricing.
- Include active current limiting circuitry which will protect the component.
- The efficiency of light output decreases with time and this becomes even worse in high temperatures
Photodiodes
Photodiodes, on the other hand, can be viewed as almost the opposite of LEDs. They change the light to an electrical current. Your smartphone’s auto-brightness feature is most probably utilizing a photodiode to detect ambient light levels. These diodes have been found to be responsive to one or the other wavelength of light and they are relatively swift in their response.
Photodiodes are used in the light sensors used in cameras and smartphones, optical communications systems, and solar cells among other uses. Because they can convert light to electrical signals in a short time, they are useful in many present-day gadgets.
Pros:
- Very fast response to light changes
- High sensitivity to light
- Can be used in a wide range of light detection applications
Cons:
- The output current is normally very much smaller and this normally has to be amplified
- Dependent on the changes in temperature
- Sensitive to light pollution, which can affect accuracy in some applications
Schottky Diodes
Schottky diodes are the darlings of the diode world because of their speed. It is characterized by the low value of forward voltage drop and the very short time of switching on. Computer hardware enthusiasts themselves might have come across Schottky diodes being used in highly efficient power supplies in gaming computers.
It is used in high-frequency switching circuits and power supply rectification circuits. They have a fast reverse recovery time and as such are suitable for applications where speed is of great importance. In case you plan to use a diode for responding to frequent changes in current, then turn to the Schottky diode.
Pros:
- High speed of switching
- Low forward voltage drop and hence high efficiency
- Good performance in high-frequency use
Cons:
- Higher reverse leakage current compared to standard silicon diodes
- More sensitive to temperature changes
- In general, the cost of this kind of device is higher than in the case of standard silicon diodes
Varactor Diodes
Varactor diodes, also referred to as Varicap diodes, behave like variable capacitors with respect to voltage. Their special characteristic is that their capacitance depends on the reverse voltage which is applied. Because of this, they are useful for the calibration of circuits and voltage-controlled oscillators.
The next time you agree on your car radio, some varactor diodes may have assisted in the act of choosing the channel. They possess a high Q factor (quality factor) which is suitable for use in circuits whose frequencies have to be controlled with high precision.
Pros:
- Perfect for uses where high voltage control of tuning is required
- High Q factor which makes it allows good selectivity in tuning circuits.
- This results in the fact that there are no moving parts hence very reliable.
Cons:
- Frequency control ranges are more limited than other mechanical variable capacitors
- May cause nonlinearity in some circuits
- More costly than fixed capacitors
Tunnel Diodes
Tunnel diodes are the quirky members of the diode family. They possess a region of negative resistance, which may be employed for some specific uses. Though they are not as popular as before tunnel diodes are used in some high-frequency applications.
Tunnel diodes can be used in high-frequency oscillators and microwave amplifiers and are sometimes included in these circuits. They are however very fast switching speeds and very low noise devices and therefore are used in applications where these attributes are useful.
Pros:
- Ultra high-speed switching
- It is capable of being driven at very high frequencies.
- Unique negative resistance characteristic useful in certain circuits
Cons:
- It has relatively small current and voltage ratings.
- Limited in their use being more complex than the standard diodes
- Not frequently offered which can cause costs to rise
Laser Diodes
Laser diodes are like LEDs on steroids. It produces parallel rays of light of a single color, which suits them for any use of applications that involve the use of a beam of light. Each movie you watch on streaming or each video game you play on the internet involves laser diodes in fiber optic networks.
They are used in optical fiber communication systems, laser pointers, barcode scanners, and many other applications. They are also required in CD/DVD/Blu-ray players and writers. They are highly efficient and capable of generating a particular wavelength of light and aid much of contemporary technology.
Pros:
- Create laser-like or parallel beams of light
- Luminous efficiency measures the ability to convert electrical energy to light.
- Diameter and length less than that of other laser types
Cons:
- Sensitive to temperature changes, often requiring temperature control
- More expensive than LEDs for general lighting applications
- Need fine control of the current and the output has to be maintained stable.
Choosing the Right Diode
Choosing the right diode for your project depends on various factors. Here are some factors to consider:
- Voltage and current ratings: Make sure it has the capability to shunt the expected voltages and currents in your circuit.
- Switching speed: In high-frequency applications, one should select a diode with a short recovery time.
- Forward voltage drop: In low voltage circuits forward voltage drop can be very important and hence low forward voltage drop is preferred.
- Reverse breakdown voltage: Choose a diode that will have the right reverse voltage breakdown according to the application to be used.
- Temperature considerations: This is particularly important if the operating temperature range of your circuit is rather narrow and you have to choose the diode that can operate in that range.
Conclusion
Diodes are among the most widely used components in electronics and these devices have very many applications. Depending on the fact of what they can do, ranging from regulating the flow of current to producing light, each type has its advantages. Knowledge of these can be useful in projects that one will be undertaking.
Want to learn more about electronic components or need help selecting the right diode for your application? Our team of experts at NSE is here to help. Contact us today for personalized advice on your electronic component needs.